This database catalogues publications of the ECCO Project and those that employ ECCO's products. Click the read more buttons for full citation, abstract, links to corresponding publications, and a list of ECCO products employed. Please acknowledge the ECCO project when utilizing our products and let us know of any publications that are missing from this list.
Publications: 1168
Hu, Shijian; Sprintall, Janet; Guan, Cong; McPhaden, Michael J; Wang, Fan; Hu, Dunxin; Cai, Wenju (2020). Deep-reaching acceleration of global mean ocean circulation over the past two decades, Science Advances, 6 (6), eaax7727, 10.1126/sciadv.aax7727.
Formatted Citation: Hu, S., J. Sprintall, C. Guan, M. J. McPhaden, F. Wang, D. Hu, and W. Cai, 2020: Deep-reaching acceleration of global mean ocean circulation over the past two decades. Science Advances, 6(6), eaax7727, doi:10.1126/sciadv.aax7727
Abstract: Ocean circulation redistributes Earth's energy and water masses and influences global climate. Under historical greenhouse warming, regional ocean currents show diverse tendencies, but whether there is an emerging trend of the global mean ocean circulation system is not yet clear. Here, we show a statistically significant increasing trend in the globally integrated oceanic kinetic energy since the early 1990s, indicating a substantial acceleration of global mean ocean circulation. The increasing trend in kinetic energy is particularly prominent in the global tropical oceans, reaching depths of thousands of meters. The deep-reaching acceleration of the ocean circulation is mainly induced by a planetary intensification of surface winds since the early 1990s. Although possibly influenced by wind changes associated with the onset of a negative Pacific decadal oscillation since the late 1990s, the recent acceleration is far larger than that associated with natural variability, suggesting that it is principally part of a long-term trend.
ECCO Consortium; Fukumori, Ichiro; Wang, Ou; Fenty, Ian; Forget, Gael; Heimbach, Patrick; Ponte, Rui M (2020). Synopsis of the ECCO Central Production Global Ocean and Sea-Ice State Estimate (Version 4 Release 4).
Formatted Citation: ECCO Consortium, I. Fukumori, O. Wang, I. Fenty, G. Forget, P. Heimbach, and R. M. Ponte, 2020: Synopsis of the ECCO Central Production Global Ocean and Sea-Ice State Estimate (Version 4 Release 4). doi:10.5281/ZENODO.3765929.
Yang, Haijun; Shen, Xingchen; Yao, Jie; Wen, Qin (2020). Portraying the Impact of the Tibetan Plateau on Global Climate, Journal of Climate, 9 (33), 3565-3583, 10.1175/JCLI-D-18-0734.1.
Formatted Citation: Yang, H., X. Shen, J. Yao, and Q. Wen, 2020: Portraying the Impact of the Tibetan Plateau on Global Climate. J. Clim., 33(9), 3565-3583, doi:10.1175/JCLI-D-18-0734.1
Abstract: As the most extensive highland in the world, the Tibetan Plateau (TP) plays an important role in shaping the global climate. Quantifying the effect of the TP on global climate is the first step for a full understanding of the TP's standing on planet Earth. Through coupled model sensitivity experiments, we draw a panorama of the TP's global impact in this paper. Our model results show that the absence of the TP would result in a 4°C colder and 10% drier climate in the Northern Hemisphere (NH). The TP has a striking remote effect on the North Atlantic. Removing the TP would enhance the westerlies in the mid- to high latitudes of the NH and weaken the easterlies over the tropical Pacific. More moisture would be relocated from the tropical Pacific to the North Atlantic, shutting down the Atlantic thermohaline circulation, which would eventually result in more than 15°C colder and 20% drier climate over the North Atlantic. Our model results suggest that the presence of the TP may have contributed greatly to the hospitable modern climate in the NH, by promoting the establishment of the thermohaline circulation in the Atlantic, and therefore enhancing the northward ocean heat transport and atmosphere moisture transport across the equator.
Portela, Esther; Kolodziejczyk, Nicolas; Maes, Christophe; Thierry, Virginie (2020). Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade, Journal of Physical Oceanography, 2 (50), 361-381, 10.1175/JPO-D-19-0128.1.
Formatted Citation: Portela, E., N. Kolodziejczyk, C. Maes, and V. Thierry, 2020: Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade. Journal of Physical Oceanography, 50(2), 361-381, doi:10.1175/JPO-D-19-0128.1
Abstract: Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness ( σ- τ) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m −3 isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The σ- τ decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade.
Ludwigsen, Carsten A.; Andersen, Ole B. (2020). Contributions to Arctic sea level from 2003 to 2015, Advances in Space Research, 10.1016/j.asr.2019.12.027.
Title: Contributions to Arctic sea level from 2003 to 2015
Type: Journal Article
Publication: Advances in Space Research
Author(s): Ludwigsen, Carsten A.; Andersen, Ole B.
Year: 2020
Formatted Citation: Ludwigsen, C. A., and O. B. Andersen, 2020: Contributions to Arctic sea level from 2003 to 2015. Advances in Space Research, doi:10.1016/j.asr.2019.12.027
Formatted Citation: Royston, S., B. Dutt Vishwakarma, R. Westaway, J. Rougier, Z. Sha, and J. Bamber, 2020: Can We Resolve the Basin-Scale Sea Level Trend Budget From GRACE Ocean Mass? J. Geophys. Res. Ocean., 125(1), doi:10.1029/2019JC015535
Jones, Daniel C.; Boland, Emma; Meijers, Andrew J. S.; Forget, Gael; Josey, Simon; Sallée, Jean-Baptiste; Shuckburgh, Emily (2020). The Sensitivity of Southeast Pacific Heat Distribution to Local and Remote Changes in Ocean Properties, Journal of Physical Oceanography, 3 (50), 773-790, 10.1175/JPO-D-19-0155.1.
Title: The Sensitivity of Southeast Pacific Heat Distribution to Local and Remote Changes in Ocean Properties
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Jones, Daniel C.; Boland, Emma; Meijers, Andrew J. S.; Forget, Gael; Josey, Simon; Sallée, Jean-Baptiste; Shuckburgh, Emily
Year: 2020
Formatted Citation: Jones, D. C., E. Boland, A. J. S. Meijers, G. Forget, S. Josey, J. Sallée, and E. Shuckburgh, 2020: The Sensitivity of Southeast Pacific Heat Distribution to Local and Remote Changes in Ocean Properties. Journal of Physical Oceanography, 50(3), 773-790, doi:10.1175/JPO-D-19-0155.1
Abstract: The Southern Ocean features ventilation pathways that transport surface waters into the subsurface thermocline on time scales from decades to centuries, sequestering anomalies of heat and carbon away from the atmosphere and thereby regulating the rate of surface warming. Despite its importance for climate sensitivity, the factors that control the distribution of heat along these pathways are not well understood. In this study, we use an observationally constrained, physically consistent global ocean model to examine the sensitivity of heat distribution in the recently ventilated subsurface Pacific (RVP) sector of the Southern Ocean to changes in ocean temperature and salinity. First, we define the RVP using numerical passive tracer release experiments that highlight the ventilation pathways. Next, we use an ensemble of adjoint sensitivity experiments to quantify the sensitivity of the RVP heat content to changes in ocean temperature and salinity. In terms of sensitivities to surface ocean properties, we find that RVP heat content is most sensitive to anomalies along the Antarctic Circumpolar Current (ACC), upstream of the subduction hotspots. In terms of sensitivities to subsurface ocean properties, we find that RVP heat content is most sensitive to basin-scale changes in the subtropical Pacific Ocean, around the same latitudes as the RVP. Despite the localized nature of mode water subduction hotspots, changes in basin-scale density gradients are an important controlling factor on heat distribution in the southeast Pacific.
Geyer, Florian; Sagen, Hanne; Cornuelle, Bruce; Mazloff, Matthew R.; Vazquez, Heriberto J. (2020). Using a regional ocean model to understand the structure and variability of acoustic arrivals in Fram Strait, The Journal of the Acoustical Society of America, 2 (147), 1042-1053, 10.1121/10.0000513.
Title: Using a regional ocean model to understand the structure and variability of acoustic arrivals in Fram Strait
Type: Journal Article
Publication: The Journal of the Acoustical Society of America
Author(s): Geyer, Florian; Sagen, Hanne; Cornuelle, Bruce; Mazloff, Matthew R.; Vazquez, Heriberto J.
Year: 2020
Formatted Citation: Geyer, F., H. Sagen, B. Cornuelle, M. R. Mazloff, and H. J. Vazquez, 2020: Using a regional ocean model to understand the structure and variability of acoustic arrivals in Fram Strait. The Journal of the Acoustical Society of America, 147(2), 1042-1053, doi:10.1121/10.0000513
Han, Lei; Huang, Rui Xin (2020). Using the Helmholtz Decomposition to Define the Indian Ocean Meridional Overturning Streamfunction, Journal of Physical Oceanography, 3 (50), 679-694, 10.1175/JPO-D-19-0218.1.
Title: Using the Helmholtz Decomposition to Define the Indian Ocean Meridional Overturning Streamfunction
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Han, Lei; Huang, Rui Xin
Year: 2020
Formatted Citation: Han, L., and R. X. Huang, 2020: Using the Helmholtz Decomposition to Define the Indian Ocean Meridional Overturning Streamfunction. Journal of Physical Oceanography, 50(3), 679-694, doi:10.1175/JPO-D-19-0218.1
Abstract: The zonally integrated flow in a basin can be separated into the divergent/nondivergent parts, and a uniquely defined meridional overturning circulation (MOC) can be calculated. For a basin with significant volume exchange at zonal open boundaries, this method is competent in removing the components associated with the nonzero source terms due to zonal transports at open boundaries. This method was applied to the zonally integrated flow in the Indian Ocean basin extended all the way to the Antarctic by virtue of the ECCO dataset. The contributions due to two major zonal flow systems at open boundaries, the Indonesian Throughflow (ITF) and the Antarctic Circumpolar Current (ACC), were well separated from the rotational flow component, and a nondivergent overturning circulation pattern was identified. Comparisons with previous studies on the MOC of the Indian Ocean in different seasons showed overall consistency but with refinements in details to the south of the entry of the ITF, reflecting the influence of ITF on the MOC pattern in the domain. Other options of decomposition are also examined.
Tandon, Neil F.; Saenko, Oleg A.; Cane, Mark A.; Kushner, Paul J. (2020). Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability, Journal of Physical Oceanography, 3 (50), 559-574, 10.1175/JPO-D-19-0129.1.
Title: Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Tandon, Neil F.; Saenko, Oleg A.; Cane, Mark A.; Kushner, Paul J.
Year: 2020
Formatted Citation: Tandon, N. F., O. A. Saenko, M. A. Cane, and P. J. Kushner, 2020: Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability. Journal of Physical Oceanography, 50(3), 559-574, doi:10.1175/JPO-D-19-0129.1
Abstract: The most prominent feature of the time-mean global meridional overturning circulation (MOC) is the Atlantic MOC (AMOC). However, interannual variability of the global MOC is shown here to be dominated by Pacific MOC (PMOC) variability over the full depth of the ocean at most latitudes. This dominance of interannual PMOC variability is robust across modern climate models and an observational state estimate. PMOC interannual variability has large-scale organization, its most prominent feature being a cross-equatorial cell spanning the tropics. Idealized experiments show that this variability is almost entirely wind driven. Interannual anomalies of zonal mean zonal wind stress produce zonally integrated Ekman transport anomalies that are larger in the Pacific Ocean than in the Atlantic Ocean, simply because the Pacific is wider than the Atlantic at most latitudes. This contrast in Ekman transport variability implies greater variability in the near-surface branch of the PMOC when compared with the near-surface branch of the AMOC. These near-surface variations in turn drive compensating flow anomalies below the Ekman layer. Because the baroclinic adjustment time is longer than a year at most latitudes, these compensating flow anomalies have baroclinic structure spanning the full depth of the ocean. Additional analysis reveals that interannual PMOC variations are the dominant contribution to interannual variations of the global meridional heat transport. There is also evidence of interaction between interannual PMOC variability and El Niño-Southern Oscillation.
Title: Heat accumulation on coral reefs mitigated by internal waves
Type: Journal Article
Publication: Nature Geoscience
Author(s): Wyatt, Alex S. J.; Leichter, James J.; Toth, Lauren T.; Miyajima, Toshihiro; Aronson, Richard B.; Nagata, Toshi
Year: 2020
Formatted Citation: Wyatt, A. S. J., J. J. Leichter, L. T. Toth, T. Miyajima, R. B. Aronson, and T. Nagata, 2020: Heat accumulation on coral reefs mitigated by internal waves. Nature Geoscience, 13(1), 28-34, doi:10.1038/s41561-019-0486-4
Formatted Citation: Peng, Q., S. Xie, D. Wang, Y. Kamae, H. Zhang, S. Hu, X. Zheng, and W. Wang, 2020: Eastern Pacific Wind Effect on the Evolution of El Niño: Implications for ENSO Diversity. J. Clim., 33(8), 3197-3212, doi:10.1175/JCLI-D-19-0435.1
Abstract: The influence of eastern tropical Pacific (EPAC; 10°S-10°N, 140°-80°W) wind anomalies on El Niño is investigated using observations and model experiments. Extreme and moderate El Niños exhibit contrasting anomalous wind patterns in the EPAC during the peak and decay phases: westerly wind anomalies during extreme El Niño and southeasterly (southwesterly) wind anomalies south (north) of the equator during moderate El Niño. Experiments with an ocean general circulation model indicate that for extreme El Niño, the eastward intrusion of westerly wind anomalies contributes to the prolonged positive sea surface temperature (SST) anomalies in the eastern equatorial Pacific throughout boreal spring by weakened upwelling and horizontal advection. For moderate El Niño, by contrast, both the meridional and zonal anomalous winds over the EPAC are important in the rapid (slow) SST cooling south (north) of the equator through advection and wind-evaporation-SST feedback. Atmospheric model experiments confirm that these EPAC anomalous winds are primarily forced by tropical SST anomalies. The interplay between wind and SST anomalies suggests positive air-sea feedbacks over EPAC during the decay phase of El Niño. Ocean model results show that the frequency of extreme El Niño increases when EPAC wind anomalies are removed, suggesting the importance of EPAC winds for El Niño diversity.
Levang, Samuel J.; Schmitt, Raymond W. (2020). Intergyre Salt Transport in the Climate Warming Response, Journal of Physical Oceanography, 1 (50), 255-268, 10.1175/JPO-D-19-0166.1.
Title: Intergyre Salt Transport in the Climate Warming Response
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Levang, Samuel J.; Schmitt, Raymond W.
Year: 2020
Formatted Citation: Levang, S. J., and R. W. Schmitt, 2020: Intergyre Salt Transport in the Climate Warming Response. Journal of Physical Oceanography, 50(1), 255-268, doi:10.1175/JPO-D-19-0166.1
Abstract: Regional connectivity is important to the global climate salinity response, particularly because salinity anomalies do not have a damping feedback with atmospheric freshwater fluxes and may therefore be advected over long distances by ocean circulation, resulting in nonlocal influences. Climate model intercomparison experiments such as CMIP5 exhibit large uncertainty in some aspects of the salinity response, hypothesized here to be a result of ocean dynamics. We use two types of Lagrangian particle tracking experiments to investigate pathways of exchange for salinity anomalies. The first uses forward trajectories to estimate average transport time scales between water cycle regimes. The second uses reverse trajectories and a freshwater accumulation method to quantitatively identify remote influences in the salinity response. Additionally, we compare velocity fields with both resolved and parameterized eddies to understand the impact of eddy stirring on intergyre exchange. These experiments show that surface anomalies are readily exchanged within the ocean gyres by the mean circulation, but intergyre exchange is slower and largely eddy driven. These dynamics are used to analyze the North Atlantic salinity response to climate warming and water cycle intensification, where the system is broadly forced with fresh surface anomalies in the subpolar gyre and salty surface anomalies in the subtropical gyres. Under these competing forcings, strong intergyre eddy fluxes carry anomalously salty subtropical water into the subpolar gyre which balances out much of the local freshwater input.
Hieronymus, Magnus; Nycander, Jonas (2020). Interannual Variability of the Overturning and Energy Transport in the Atmosphere and Ocean During the Late Twentieth Century with Implications for Precipitation and Sea Level, Journal of Climate, 1 (33), 317-338, 10.1175/JCLI-D-19-0204.1.
Title: Interannual Variability of the Overturning and Energy Transport in the Atmosphere and Ocean During the Late Twentieth Century with Implications for Precipitation and Sea Level
Type: Journal Article
Publication: Journal of Climate
Author(s): Hieronymus, Magnus; Nycander, Jonas
Year: 2020
Formatted Citation: Hieronymus, M., and J. Nycander, 2020: Interannual Variability of the Overturning and Energy Transport in the Atmosphere and Ocean During the Late Twentieth Century with Implications for Precipitation and Sea Level. J. Clim., 33(1), 317-338, doi:10.1175/JCLI-D-19-0204.1
Abstract: The overturning circulations in the atmosphere and ocean transport energy from the tropics to higher latitudes and thereby modulate Earth's climate. The interannual variability in the overturning over the last 40 years is found to be dominated by two coupled atmosphere-ocean modes. The first is related to the meridional motion of the intertropical convergence zone and the second to El Niño. Both modes have a strong influence on the sea level variability in the tropical Indo-Pacific Ocean. The interannual variability of the cross-equatorial energy transport is dominated by the first mode, and the variability is larger in the Indo-Pacific Ocean than in the Atlantic Ocean or the atmosphere. Our results suggest an important role of oceanic energy transport in setting precipitation patterns in the tropics and a key role of the Indo-Pacific Ocean as a climate modulator.
Zhang, Yanxu; Soerensen, Anne L.; Schartup, Amina T.; Sunderland, Elsie M. (2020). A Global Model for Methylmercury Formation and Uptake at the Base of Marine Food Webs, Global Biogeochemical Cycles, 2 (34), 10.1029/2019GB006348.
Title: A Global Model for Methylmercury Formation and Uptake at the Base of Marine Food Webs
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): Zhang, Yanxu; Soerensen, Anne L.; Schartup, Amina T.; Sunderland, Elsie M.
Year: 2020
Formatted Citation: Zhang, Y., A. L. Soerensen, A. T. Schartup, and E. M. Sunderland, 2020: A Global Model for Methylmercury Formation and Uptake at the Base of Marine Food Webs. Global Biogeochemical Cycles, 34(2), doi:10.1029/2019GB006348
Formatted Citation: Strobach, E., A. Molod, A. Trayanov, G. Forget, J. Campin, C. Hill, and D. Menemenlis, 2020: Three-to-Six-Day Air-Sea Oscillation in Models and Observations. Geophys. Res. Lett., e2019GL085837, doi:10.1029/2019GL085837
Formatted Citation: Nelson, A., B. Arbic, D. Menemenlis, W. Peltier, M. Alford, N. Grisouard, and J. Klymak, 2020: Improved Internal Wave Spectral Continuum in a Regional Ocean Model. J. Geophys. Res. Ocean., doi:10.1029/2019JC015974
Luecke, Conrad A.; Arbic, Brian K.; Richman, James G.; Shriver, Jay F.; Alford, Matthew H.; Ansong, Joseph K.; Bassette, Steven L.; Buijsman, Maarten C.; Menemenlis, Dimitris; Scott, Robert B.; Timko, Patrick G.; Voet, Gunnar; Wallcraft, Alan J.; Zamudio, Luis (2020). Statistical Comparisons of Temperature Variance and Kinetic Energy in Global Ocean Models and Observations: Results from Mesoscale to Internal Wave Frequencies, Journal of Geophysical Research: Oceans, 10.1029/2019JC015306.
Title: Statistical Comparisons of Temperature Variance and Kinetic Energy in Global Ocean Models and Observations: Results from Mesoscale to Internal Wave Frequencies
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Luecke, Conrad A.; Arbic, Brian K.; Richman, James G.; Shriver, Jay F.; Alford, Matthew H.; Ansong, Joseph K.; Bassette, Steven L.; Buijsman, Maarten C.; Menemenlis, Dimitris; Scott, Robert B.; Timko, Patrick G.; Voet, Gunnar; Wallcraft, Alan J.; Zamudio, Luis
Year: 2020
Formatted Citation: Luecke, C. A. and Coauthors, 2020: Statistical Comparisons of Temperature Variance and Kinetic Energy in Global Ocean Models and Observations: Results from Mesoscale to Internal Wave Frequencies. J. Geophys. Res. Ocean., doi:10.1029/2019JC015306
Formatted Citation: Siegelman, L., P. Klein, P. Rivière, A. F. Thompson, H. S. Torres, M. Flexas, and D. Menemenlis, 2020: Enhanced upward heat transport at deep submesoscale ocean fronts. Nature Geoscience, 13(1), 50-55, doi:10.1038/s41561-019-0489-1
Formatted Citation: Qiu, B., S. Chen, P. Klein, H. Torres, J. Wang, L. Fu, and D. Menemenlis, 2020: Reconstructing Upper-Ocean Vertical Velocity Field from Sea Surface Height in the Presence of Unbalanced Motion. Journal of Physical Oceanography, 50(1), 55-79, doi:10.1175/JPO-D-19-0172.1
Abstract: Reconstructability of upper-ocean vertical velocity w and vorticity ζ fields from high-resolution sea surface height (SSH) data is explored using the global 1/48° horizontal-resolution MITgcm output in the context of the forthcoming Surface Water and Ocean Topography (SWOT) mission. By decomposing w with an omega equation of the primitive equation system and by taking into account the measurement design of the SWOT mission, this study seeks to reconstruct the subinertial, balanced w and ζ signals. By adopting the effective surface quasigeostrophic (eSQG) framework and applying to the Kuroshio Extension region of the North Pacific, we find that the target and reconstructed fields have a spatial correlation of ~0.7 below the mixed layer for w and 0.7-0.9 throughout the 1000-m upper ocean for ζ in the error-free scenario. By taking the SWOT sampling and measurement errors into account, the spatial correlation is found to decrease to 0.4-0.6 below the mixed layer for w and 0.6-0.7 for ζ, respectively. For both w and ζ reconstruction, the degradation due to the SWOT errors is more significant in the surface layer and for smaller-scale signals. The impact of errors lessens with the increasing depth and lengthening horizontal scales.
Erickson, Zachary K.; Thompson, Andrew F.; Callies, Jörn; Yu, Xiaolong; Garabato, Alberto Naveira; Klein, Patrice (2020). The Vertical Structure of Open-Ocean Submesoscale Variability during a Full Seasonal Cycle, Journal of Physical Oceanography, 1 (50), 145-160, 10.1175/JPO-D-19-0030.1.
Title: The Vertical Structure of Open-Ocean Submesoscale Variability during a Full Seasonal Cycle
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Erickson, Zachary K.; Thompson, Andrew F.; Callies, Jörn; Yu, Xiaolong; Garabato, Alberto Naveira; Klein, Patrice
Year: 2020
Formatted Citation: Erickson, Z. K., A. F. Thompson, J. Callies, X. Yu, A. N. Garabato, and P. Klein, 2020: The Vertical Structure of Open-Ocean Submesoscale Variability during a Full Seasonal Cycle. Journal of Physical Oceanography, 50(1), 145-160, doi:10.1175/JPO-D-19-0030.1
Abstract: Submesoscale dynamics are typically intensified at boundaries and assumed to weaken below the mixed layer in the open ocean. Here, we assess both the seasonality and the vertical distribution of submesoscale motions in an open-ocean region of the northeast Atlantic. Second-order structure functions, or variance in properties separated by distance, are calculated from submesoscale-resolving ocean glider and mooring observations, as well as a 1/48° numerical ocean model. This dataset combines a temporal coverage that extends through a full seasonal cycle, a horizontal resolution that captures spatial scales as small as 1 km, and vertical sampling that provides near-continuous coverage over the upper 1000 m. While kinetic and potential energies undergo a seasonal cycle, being largest during the winter, structure function slopes, influenced by dynamical characteristics, do not exhibit a strong seasonality. Furthermore, structure function slopes show weak vertical variations; there is not a strong change in properties across the base of the mixed layer. Additionally, we compare the observations to output from a high-resolution numerical model. The model does not represent variability associated with superinertial motions and does not capture an observed reduction in submesoscale kinetic energy that occurs throughout the water column in spring. Overall, these results suggest that the transfer of mixed layer submesoscale variability down to depths below the traditionally defined mixed layer is important throughout the weakly stratified subpolar mode waters.
Mauzole, Y. L.; Torres, H. S.; Fu, L.-L. (2020). Patterns and Dynamics of SST Fronts in the California Current System, Journal of Geophysical Research: Oceans, 2 (125), 10.1029/2019JC015499.
Title: Patterns and Dynamics of SST Fronts in the California Current System
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Mauzole, Y. L.; Torres, H. S.; Fu, L.-L.
Year: 2020
Formatted Citation: Mauzole, Y. L., H. S. Torres, and L. Fu, 2020: Patterns and Dynamics of SST Fronts in the California Current System. J. Geophys. Res. Ocean., 125(2), doi:10.1029/2019JC015499
Siegelman, Lia (2020). Energetic Submesoscale Dynamics in the Ocean Interior, Journal of Physical Oceanography, 3 (50), 727-749, 10.1175/JPO-D-19-0253.1.
Title: Energetic Submesoscale Dynamics in the Ocean Interior
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Siegelman, Lia
Year: 2020
Formatted Citation: Siegelman, L., 2020: Energetic Submesoscale Dynamics in the Ocean Interior. Journal of Physical Oceanography, 50(3), 727-749, doi:10.1175/JPO-D-19-0253.1
Abstract: Submesoscale ocean processes, characterized by order-1 Rossby and Richardson numbers, are currently thought to be mainly confined to the ocean surface mixed layer, whereas the ocean interior is commonly assumed to be in quasigeostrophic equilibrium. Here, a realistic numerical simulation in the Antarctic Circumpolar Current, with a 1/48° horizontal resolution and tidal forcing, is used to demonstrate that the ocean interior departs from the quasigeostrophic regime down to depths of 900 m, that is, well below the mixed layer. Results highlight that, contrary to the classical paradigm, the ocean interior is strongly ageostrophic, with a pronounced cyclone-anticyclone asymmetry and a dominance of frontogenesis over frontolysis. Numerous vortices and filaments, from the surface down to 900 m, are characterized by large Rossby and low Richardson numbers, strong lateral gradients of buoyancy, and vigorous ageostrophic frontogenesis. These deep submesoscales fronts are only weakly affected by internal gravity waves and drive intense upward vertical heat fluxes, consistent with recent observations in the Antarctic Circumpolar Current and the Gulf Stream. As such, deep submesoscale fronts are an efficient pathway for the transport of heat from the ocean interior to the surface, suggesting the presence of an intensified oceanic restratification at depth.
Mazloff, Matthew R.; Cornuelle, Bruce; Gille, Sarah T.; Wang, Jinbo (2020). The Importance of Remote Forcing for Regional Modeling of Internal Waves, Journal of Geophysical Research: Oceans, 2 (125), 10.1029/2019JC015623.
Title: The Importance of Remote Forcing for Regional Modeling of Internal Waves
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Mazloff, Matthew R.; Cornuelle, Bruce; Gille, Sarah T.; Wang, Jinbo
Year: 2020
Formatted Citation: Mazloff, M. R., B. Cornuelle, S. T. Gille, and J. Wang, 2020: The Importance of Remote Forcing for Regional Modeling of Internal Waves. J. Geophys. Res. Ocean., 125(2), doi:10.1029/2019JC015623
Dong, Jihai; Fox-Kemper, Baylor; Zhang, Hong; Dong, Changming (2020). The Seasonality of Submesoscale Energy Production, Content, and Cascade, Geophysical Research Letters, 6 (47), 10.1029/2020GL087388.
Formatted Citation: Dong, J., B. Fox-Kemper, H. Zhang, and C. Dong, 2020: The Seasonality of Submesoscale Energy Production, Content, and Cascade. Geophys. Res. Lett., 47(6), doi:10.1029/2020GL087388
Johns, Elizabeth M.; Lumpkin, Rick; Putman, Nathan F.; Smith, Ryan H.; Muller-Karger, Frank E.; T. Rueda-Roa, Digna; Hu, Chuanmin; Wang, Mengqiu; Brooks, Maureen T.; Gramer, Lewis J.; Werner, Francisco E. (2020). The establishment of a pelagic Sargassum population in the tropical Atlantic: Biological consequences of a basin-scale long distance dispersal event, Progress in Oceanography (182), 102269, 10.1016/j.pocean.2020.102269.
Title: The establishment of a pelagic Sargassum population in the tropical Atlantic: Biological consequences of a basin-scale long distance dispersal event
Type: Journal Article
Publication: Progress in Oceanography
Author(s): Johns, Elizabeth M.; Lumpkin, Rick; Putman, Nathan F.; Smith, Ryan H.; Muller-Karger, Frank E.; T. Rueda-Roa, Digna; Hu, Chuanmin; Wang, Mengqiu; Brooks, Maureen T.; Gramer, Lewis J.; Werner, Francisco E.
Year: 2020
Formatted Citation: Johns, E. M. and Coauthors, 2020: The establishment of a pelagic Sargassum population in the tropical Atlantic: Biological consequences of a basin-scale long distance dispersal event. Progress in Oceanography, 182, 102269, doi:10.1016/j.pocean.2020.102269
Anandh, Thanka Swamy; Das, Bijan Kumar; Kuttippurath, J.; Chakraborty, Arun (2020). A coupled model analyses on the interaction between oceanic eddies and tropical cyclones over the Bay of Bengal, Ocean Dynamics, 3 (70), 327-337, 10.1007/s10236-019-01330-x.
Formatted Citation: Anandh, T. S., B. K. Das, J. Kuttippurath, and A. Chakraborty, 2020: A coupled model analyses on the interaction between oceanic eddies and tropical cyclones over the Bay of Bengal. Ocean Dynamics, 70(3), 327-337, doi:10.1007/s10236-019-01330-x
Klos, Anna; Bogusz, Janusz; Bos, Machiel S.; Gruszczynska, Marta (2020). Modelling the GNSS Time Series: Different Approaches to Extract Seasonal Signals.
Title: Modelling the GNSS Time Series: Different Approaches to Extract Seasonal Signals
Type: Book Section
Publication:
Author(s): Klos, Anna; Bogusz, Janusz; Bos, Machiel S.; Gruszczynska, Marta
Year: 2020
Formatted Citation: Klos, A., J. Bogusz, M. S. Bos, and M. Gruszczynska, 2020: Modelling the GNSS Time Series: Different Approaches to Extract Seasonal Signals., 211-237, doi:10.1007/978-3-030-21718-1_7
Wang, Linsong; Chen, Chao; Ma, Xian; Fu, Zhengyan; Zheng, Yuhao; Peng, Zhenran (2020). Evaluation of GRACE mascon solutions using in-situ geodetic data: The case of hydrologic-induced crust displacement in the Yangtze River Basin, Science of The Total Environment (707), 135606, 10.1016/j.scitotenv.2019.135606.
Formatted Citation: Wang, L., C. Chen, X. Ma, Z. Fu, Y. Zheng, and Z. Peng, 2020: Evaluation of GRACE mascon solutions using in-situ geodetic data: The case of hydrologic-induced crust displacement in the Yangtze River Basin. Science of The Total Environment, 707, 135606, doi:10.1016/j.scitotenv.2019.135606
Wang, Yingying; Luo, Yiyong (2020). Variability of spice injection in the upper ocean of the southeastern Pacific during 1992-2016, Climate Dynamics, 5-6 (54), 3185-3200, 10.1007/s00382-020-05164-y.
Title: Variability of spice injection in the upper ocean of the southeastern Pacific during 1992-2016
Type: Journal Article
Publication: Climate Dynamics
Author(s): Wang, Yingying; Luo, Yiyong
Year: 2020
Formatted Citation: Wang, Y., and Y. Luo, 2020: Variability of spice injection in the upper ocean of the southeastern Pacific during 1992-2016. Climate Dynamics, 54(5-6), 3185-3200, doi:10.1007/s00382-020-05164-y
Li; Huang; Chen; Dam; Fok; Zhao; Wu; Wang (2020). Quantitative Evaluation of Environmental Loading Induced Displacement Products for Correcting GNSS Time Series in CMONOC, Remote Sensing, 4 (12), 594, 10.3390/rs12040594.
Title: Quantitative Evaluation of Environmental Loading Induced Displacement Products for Correcting GNSS Time Series in CMONOC
Type: Journal Article
Publication: Remote Sensing
Author(s): Li; Huang; Chen; Dam; Fok; Zhao; Wu; Wang
Year: 2020
Formatted Citation: Li, Huang, Chen, Dam, Fok, Zhao, Wu, and Wang, 2020: Quantitative Evaluation of Environmental Loading Induced Displacement Products for Correcting GNSS Time Series in CMONOC. Remote Sensing, 12(4), 594, doi:10.3390/rs12040594
Abstract: Mass redistribution within the Earth system deforms the surface elastically. Loading theory allows us to predict loading induced displacement anywhere on the Earth's surface using environmental loading models, e.g., Global Land Data Assimilation System. In addition, different publicly available loading products are available. However, there are differences among those products and the differences among the combinations of loading models cannot be ignored when precisions of better than 1 cm are required. Many scholars have applied these loading corrections to Global Navigation Satellite System (GNSS) time series from mainland China without considering or discussing the differences between the available models. Evaluating the effects of different loading products over this region is of paramount importance for accurately removing the loading signal. In this study, we investigate the performance of these different publicly available loading products on the scatter of GNSS time series from the Crustal Movement Observation Network of China. We concentrate on five different continental water storage loading models, six different non-tidal atmospheric loading models, and five different non-tidal oceanic loading models. We also investigate all the different combinations of loading products. The results show that the difference in RMS reduction can reach 20% in the vertical component depending on the loading correction applied. We then discuss the performance of different loading combinations and their effects on the noise characteristics of GNSS height time series and horizontal velocities. The results show that the loading products from NASA may be the best choice for corrections in mainland China. This conclusion could serve as an important reference for loading products users in this region.
Chaudhuri, Anya; Shankar, D; Aparna, S G; Amol, P; Fernando, V; Kankonkar, A; Michael, G S; Satelkar, N P; Khalap, S T; Tari, A P; Gaonkar, M G; Ghatkar, S; Khedekar, R R (2020). Observed variability of the West India Coastal Current on the continental slope from 2009-2018, Journal of Earth System Science, 1 (129), 57, 10.1007/s12040-019-1322-3.
Title: Observed variability of the West India Coastal Current on the continental slope from 2009-2018
Type: Journal Article
Publication: Journal of Earth System Science
Author(s): Chaudhuri, Anya; Shankar, D; Aparna, S G; Amol, P; Fernando, V; Kankonkar, A; Michael, G S; Satelkar, N P; Khalap, S T; Tari, A P; Gaonkar, M G; Ghatkar, S; Khedekar, R R
Year: 2020
Formatted Citation: Chaudhuri, A. and Coauthors, 2020: Observed variability of the West India Coastal Current on the continental slope from 2009-2018. Journal of Earth System Science, 129(1), 57, doi:10.1007/s12040-019-1322-3
Mackay, Neill; Wilson, Chris; Holliday, N. Penny; Zika, Jan D. (2020). The observation-based application of a Regional Thermohaline Inverse Method to diagnose the formation and transformation of water masses north of the OSNAP array from 2013-2015, Journal of Physical Oceanography, 10.1175/jpo-d-19-0188.1.
Title: The observation-based application of a Regional Thermohaline Inverse Method to diagnose the formation and transformation of water masses north of the OSNAP array from 2013-2015
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Mackay, Neill; Wilson, Chris; Holliday, N. Penny; Zika, Jan D.
Year: 2020
Formatted Citation: Mackay, N., C. Wilson, N. P. Holliday, and J. D. Zika, 2020: The observation-based application of a Regional Thermohaline Inverse Method to diagnose the formation and transformation of water masses north of the OSNAP array from 2013-2015. Journal of Physical Oceanography, doi:10.1175/jpo-d-19-0188.1
Abstract: The strength of the Meridional Overturning Circulation (MOC) in the North Atlantic is dependent upon the formation of dense waters that occurs at high northern latitudes. Wintertime deep convection in the Labrador and Irminger Seas forms the intermediate water mass known as Labrador Sea Water (LSW). Changes in the rate of formation and subsequent export of LSW are thought to play a role in MOC variability, but formation rates are uncertain and the link between formation and export is complex. We present the first observation-based application of a recently developed Regional Thermohaline Inverse Method (RTHIM) to a region encompassing the Arctic and part of the North Atlantic subpolar gyre for the years 2013, 2014 and 2015. RTHIM is a novel method which can diagnose the formation and export rates of water masses such as the LSW identified by their temperature and salinity, apportioning the formation rates into contributions from surface fluxes and interior mixing. We find LSW formation rates of up to 12 Sv during 2014-15, a period of strong wintertime convection, and around half that value during 2013 when convection was weak. We also show that the newly convected water is not exported directly, but instead is mixed isopycnally with warm, salty waters that have been advected into the region, before the products are then exported. RTHIM solutions for 2015 volume, heat and freshwater transports are compared with observations from a mooring array deployed for the Overturning in the Subpolar North Atlantic Program (OSNAP) and show good agreement, lending validity to our results.
Keywords:
ECCO Products Used: ECCO-V4
URL:
Other URLs:
Quinn, K J; Ponte, R M; Heimbach, P; Fukumori, I; Campin, Jean-Michel (2019). Ocean angular momentum from a recent global state estimate, with assessment of uncertainties, Geophysical Journal International, 1 (216), 584-597.
Title: Ocean angular momentum from a recent global state estimate, with assessment of uncertainties
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Quinn, K J; Ponte, R M; Heimbach, P; Fukumori, I; Campin, Jean-Michel
Year: 2019
Formatted Citation: Quinn, K. J., R. M. Ponte, P. Heimbach, I. Fukumori, and J. Campin, 2019: Ocean angular momentum from a recent global state estimate, with assessment of uncertainties. Geophysical Journal International, 216(1), 584-597, http://dx.doi.org/10.1093/gji/ggy452
Abstract: Earth rotation studies require accurate knowledge of the global oceanic velocity and mass fields, for proper accounting of ocean angular momentum (OAM) effects on the planetary budget. We analyse a new OAM series (1992-2015) based on the solution of a global general circulation model constrained to most existing ocean data. The impact of the data-constrained optimization on OAM is substantial, and particularly essential for calculating effects of global mean ocean mass changes, which can be important for determining annual cycles and long term trends in OAM. The contributions of sea ice to OAM variations, also estimated, are found to be negligible. Uncertainties in OAM series are assessed by comparison with other available estimates. Results indicate low signal-to-noise ratios for all the analysed OAM series. Comparisons with geodetic, atmospheric and hydrologic data, in the context of the planetary angular momentum budget, point to the continued need for improvements in some or all of the series. Possible paths are offered for producing better OAM estimates in the future.
Title: ENSO-Related Global Ocean Heat Content Variations
Type: Journal Article
Publication: Journal of Climate
Author(s): Wu, Quran; Zhang, Xuebin; Church, John A; Hu, Jianyu
Year: 2019
Formatted Citation: Wu, Q., X. Zhang, J. A. Church, and J. Hu, 2019: ENSO-Related Global Ocean Heat Content Variations. J. Clim., 32(1), 45-68, doi:10.1175/JCLI-D-17-0861.1
Abstract: The modulation of the full-depth global integrated ocean heat content (GOHC) by El Niño-Southern Oscillation (ENSO) has been estimated in various studies. However, the quantitative results and the mechanisms at work remain uncertain. Here, a dynamically consistent ocean state estimate is utilized to study the large-scale integrated heat content variations during ENSO events for the global ocean. The full-depth GOHC exhibits a cooling tendency during the peak and decaying phases of El Niño, which is a result of the negative surface heat flux (SHF) anomaly in the tropics (30°S-30°N), partially offset by the positive SHF anomaly at higher latitudes. The tropical SHF anomaly acts as a lagged response to damp the convergence of oceanic heat transport, which redistributes heat from the extratropics and the subsurface layers (100-440 m) into the upper tropical oceans (0-100 m) during the onset and peak of El Niño. These results highlight the global nature of the oceanic heat redistribution during ENSO events, as well as how the redistribution process affects the full-depth GOHC. The meridional heat exchange across 30°S and 30°N is driven by ocean current anomalies, while multiple processes contribute to the vertical heat exchange across 100 m simultaneously. Heat advection due to unbalanced mass transport is distinguished from the mass balanced one, with significant contributions from the meridional and zonal overturning cells being identified for the latter in the vertical direction. Results presented here have implications for monitoring the planetary energy budget and evaluating ENSO's global imprints on ocean heat content in different estimates.
O'Callaghan, B.; Chabchoub, A.; Waseda, T. (2019). Marine current energy in Eastern Australia: Evolution of currents and mesoscale anticyclonic eddies, Advances in Renewable Energies Offshore, 31-38.
Title: Marine current energy in Eastern Australia: Evolution of currents and mesoscale anticyclonic eddies
Type: Book Section
Publication: Advances in Renewable Energies Offshore
Author(s): O'Callaghan, B.; Chabchoub, A.; Waseda, T.
Year: 2019
Formatted Citation: O'Callaghan, B., A. Chabchoub, and T. Waseda, 2019: Marine current energy in Eastern Australia: Evolution of currents and mesoscale anticyclonic eddies. Advances in Renewable Energies Offshore, Taylor & Francis Group, 31-38, https://books.google.com/books?hl=en&lr=&id=YMp6DwAAQBAJ&oi=fnd&pg=PA31&dq=ecco2+menemenlis&ots=78V-4WfRD_&sig=N36qJ6EV-2lXg6fmpv_loylDAbo#v=twopage&q=ecco2 menemenlis&f=true
Qu, Tangdong; Fukumori, Ichiro; Fine, Rana A. (2019). Spin-up of the Southern Hemisphere Super Gyre, Journal of Geophysical Research: Oceans (124), 2018JC014391, 10.1029/2018JC014391.
Title: Spin-up of the Southern Hemisphere Super Gyre
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Qu, Tangdong; Fukumori, Ichiro; Fine, Rana A.
Year: 2019
Formatted Citation: Qu, T., I. Fukumori, and R. A. Fine, 2019: Spin-up of the Southern Hemisphere Super Gyre. J. Geophys. Res. Ocean., 124, 2018JC014391, doi:10.1029/2018JC014391
Ott, Lesley; Pawson, Steven; Collatz, Jim; Watson, Gregg; Menemenlis, Dimitris; Brix, Holger; Rousseaux, Cecile; Bowman, Kevin; Liu, Junjie; Eldering, Annmarie; Gunson, Michael; Kawa, Stephan R. (2019). Quantifying the observability of CO2 flux uncertainty in atmospheric CO2 records using products from NASA’s Carbon Monitoring Flux Pilot Project, NASA, 21.
Title: Quantifying the observability of CO2 flux uncertainty in atmospheric CO2 records using products from NASA’s Carbon Monitoring Flux Pilot Project
Type: Report
Publication: NASA
Author(s): Ott, Lesley; Pawson, Steven; Collatz, Jim; Watson, Gregg; Menemenlis, Dimitris; Brix, Holger; Rousseaux, Cecile; Bowman, Kevin; Liu, Junjie; Eldering, Annmarie; Gunson, Michael; Kawa, Stephan R.
Year: 2019
Formatted Citation: Ott, L. and Coauthors, 2019: Quantifying the observability of CO2 flux uncertainty in atmospheric CO2 records using products from NASA's Carbon Monitoring Flux Pilot Project., Greenbelt, MD, 21 pp. https://ntrs.nasa.gov/search.jsp?R=20150001279.
Abstract: NASAs Carbon Monitoring System (CMS) Flux Pilot Project (FPP) was designed to better understand contemporary carbon fluxes by bringing together state-of-the art models with remote sensing datasets. Here we report on simulations using NASAs Goddard Earth Observing System Model, version 5 (GEOS-5) which was used to evaluate the consistency of two different sets of observationally constrained land and ocean fluxes with atmospheric CO2 records. Despite the strong data constraint, the average difference in annual terrestrial biosphere flux between the two land (NASA Ames CASA and CASA-GFED) models is 1.7 Pg C for 2009-2010. Ocean models (NOBM and ECCO2-Darwin) differ by 35 in their global estimates of carbon flux with particularly strong disagreement in high latitudes. Based upon combinations of terrestrial and ocean fluxes, GEOS-5 reasonably simulated the seasonal cycle observed at northern hemisphere surface sites and by the Greenhouse gases Observing SATellite (GOSAT) while the model struggled to simulate the seasonal cycle at southern hemisphere surface locations. Though GEOS-5 was able to reasonably reproduce the patterns of XCO2 observed by GOSAT, it struggled to reproduce these aspects of AIRS observations. Despite large differences between land and ocean flux estimates, resulting differences in atmospheric mixing ratio were small, typically less than 5 ppmv at the surface and 3 ppmv in the XCO2 column. A statistical analysis based on the variability of observations shows that flux differences of these magnitudes are difficult to distinguish from natural variability, regardless of measurement platform.
Formatted Citation: Cessi, P., 2019: The Global Overturning Circulation. Annual Review of Marine Science, 11(1), 249-270, doi:10.1146/annurev-marine-010318-095241
Abstract: In this article, I use the Estimating the Circulation and Climate of the Ocean version 4 (ECCO4) reanalysis to estimate the residual meridional overturning circulation, zonally averaged, over the separate Atlantic and Indo-Pacific sectors. The abyssal component of this estimate differs quantitatively from previously published estimates that use comparable observations, indicating that this component is still undersampled. I also review recent conceptual models of the oceanic meridional overturning circulation and of the mid-depth and abyssal stratification. These theories show that dynamics in the Antarctic circumpolar region are essential in determining the deep and abyssal stratification. In addition, they show that a mid-depth cell consistent with observational estimates is powered by the wind stress in the Antarctic circumpolar region, while the abyssal cell relies on interior diapycnal mixing, which is bottom intensified.
Formatted Citation: Peng, Q., S. Xie, D. Wang, X. Zheng, and H. Zhang, 2019: Coupled ocean-atmosphere dynamics of the 2017 extreme coastal El Niño. Nature Communications, 10(1), 298, doi:10.1038/s41467-018-08258-8
Abstract: In March 2017, sea surface temperatures off Peru rose above 28 °C, causing torrential rains that affected the lives of millions of people. This coastal warming is highly unusual in that it took place with a weak La Niña state. Observations and ocean model experiments show that the downwelling Kelvin waves caused by strong westerly wind events over the equatorial Pacific, together with anomalous northerly coastal winds, are important. Atmospheric model experiments further show the anomalous coastal winds are forced by the coastal warming. Taken together, these results indicate a positive feedback off Peru between the coastal warming, atmospheric deep convection, and the coastal winds. These coupled processes provide predictability. Indeed, initialized on as early as 1 February 2017, seasonal prediction models captured the extreme rainfall event. Climate model projections indicate that the frequency of extreme coastal El Niño will increase under global warming.
Trossman, D. S.; Tyler, R. H. (2019). Predictability of Ocean Heat Content from Electrical Conductance, Journal of Geophysical Research: Oceans, 10.1029/2018JC014740.
Title: Predictability of Ocean Heat Content from Electrical Conductance
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Trossman, D. S.; Tyler, R. H.
Year: 2019
Formatted Citation: Trossman, D. S., and R. H. Tyler, 2019: Predictability of Ocean Heat Content from Electrical Conductance. J. Geophys. Res. Ocean., 0(0), doi:10.1029/2018JC014740
Abstract: Ocean heat content (OHC) is a key climate variable that needs to be monitored to know how Earth's energy imbalance is changing, yet observing OHC remains a challenge. The present study examines whether a depth integral of the ocean's electrical conductivity (?conductance?), which may be inferred from both in situ methods and satellite magnetometers over the global ocean, could help monitor OHC. The ocean's electrical conductivity locally depends on temperature, salinity, and pressure, but it is not as well known how the conductance depends on OHC and ocean salt content. By examining the output of an ocean state estimate shown to agree well with observations that have not been assimilated, this study evaluates the fundamental limitations of using perfectly known ocean conductance to predict OHC, rather than the challenges associated with accounting for observational error. It is found that the ocean's conductance and OHC fields are nonlinearly related but nevertheless highly correlated. A statistical framework tends to predict OHC more accurately than ocean salt content from ocean conductance in regions where conductivity is more sensitive to salinity than temperature. The annually (bidecadally) averaged OHC can be predicted from a combination of conductance and depth-averaged conductivity ocean fields to within nearly 0.1% (1%) error globally and even more accurately in many poorly observed (e.g., ice-covered) regions. Practical application of this statistical framework to monitor OHC requires examination of the effect of uncertainties in the observed bathymetry and ocean conductance, which vary with application.
Keywords: conductance, conductivity, heat, ocean, prediction, state estimate
Zanna, Laure; Khatiwala, Samar; Gregory, Jonathan M; Ison, Jonathan; Heimbach, Patrick (2019). Global reconstruction of historical ocean heat storage and transport, Proceedings of the National Academy of Sciences, 4 (116), 1126 LP - 1131, 10.1073/pnas.1808838115.
Title: Global reconstruction of historical ocean heat storage and transport
Type: Journal Article
Publication: Proceedings of the National Academy of Sciences
Author(s): Zanna, Laure; Khatiwala, Samar; Gregory, Jonathan M; Ison, Jonathan; Heimbach, Patrick
Year: 2019
Formatted Citation: Zanna, L., S. Khatiwala, J. M. Gregory, J. Ison, and P. Heimbach, 2019: Global reconstruction of historical ocean heat storage and transport. Proceedings of the National Academy of Sciences, 116(4), 1126 LP - 1131, doi:10.1073/pnas.1808838115
Abstract: Since the 19th century, rising greenhouse gas concentrations have caused the ocean to absorb most of the Earth's excess heat and warm up. Before the 1990s, most ocean temperature measurements were above 700 m and therefore, insufficient for an accurate global estimate of ocean warming. We present a method to reconstruct ocean temperature changes with global, full-depth ocean coverage, revealing warming of 436 ×1021 J since 1871. Our reconstruction, which agrees with other estimates for the well-observed period, demonstrates that the ocean absorbed as much heat during 1921-1946 as during 1990-2015. Since the 1950s, up to one-half of excess heat in the Atlantic Ocean at midlatitudes has come from other regions via circulation-related changes in heat transport.Most of the excess energy stored in the climate system due to anthropogenic greenhouse gas emissions has been taken up by the oceans, leading to thermal expansion and sea-level rise. The oceans thus have an important role in the Earth's energy imbalance. Observational constraints on future anthropogenic warming critically depend on accurate estimates of past ocean heat content (OHC) change. We present a reconstruction of OHC since 1871, with global coverage of the full ocean depth. Our estimates combine timeseries of observed sea surface temperatures with much longer historical coverage than those in the ocean interior together with a representation (a Green's function) of time-independent ocean transport processes. For 1955-2017, our estimates are comparable with direct estimates made by infilling the available 3D time-dependent ocean temperature observations. We find that the global ocean absorbed heat during this period at a rate of 0.30 ± 0.06 W/m2 in the upper 2,000 m and 0.028 ± 0.026 W/m2 below 2,000 m, with large decadal fluctuations. The total OHC change since 1871 is estimated at 436 ± 91 ×1021 J, with an increase during 1921-1946 (145 ± 62 ×1021 J) that is as large as during 1990-2015. By comparing with direct estimates, we also infer that, during 1955-2017, up to one-half of the Atlantic Ocean warming and thermosteric sea-level rise at low latitudes to midlatitudes emerged due to heat convergence from changes in ocean transport.
Ding, Yang; Bao, Xianwen; Yao, Zhigang; Bi, Congcong; Wan, Kai; Bao, Min; Jiang, Zhipeng; Song, Jun; Gao, Jia (2019). Observational and model studies of synoptic current fluctuations in the Bohai Strait on the Chinese continental shelf, Ocean Dynamics, 10.1007/s10236-019-01247-5.
Formatted Citation: Ding, Y. and Coauthors, 2019: Observational and model studies of synoptic current fluctuations in the Bohai Strait on the Chinese continental shelf. Ocean Dynamics, doi:10.1007/s10236-019-01247-5
Chi, J; Du, Y; Zhang, Y; Nie, X; Shi, P; Qu, T (2019). A new perspective of the 2014/15 failed El Niño as seen from ocean salinity, Scientific Reports, 1 (9), 2720, 10.1038/s41598-019-38743-z.
Title: A new perspective of the 2014/15 failed El Niño as seen from ocean salinity
Type: Journal Article
Publication: Scientific Reports
Author(s): Chi, J; Du, Y; Zhang, Y; Nie, X; Shi, P; Qu, T
Year: 2019
Formatted Citation: Chi, J., Y. Du, Y. Zhang, X. Nie, P. Shi, and T. Qu, 2019: A new perspective of the 2014/15 failed El Niño as seen from ocean salinity. Scientific Reports, 9(1), 2720, doi:10.1038/s41598-019-38743-z
Abstract: This study investigates the 2014/15 failed El Niño using salinity from an ocean general circulation model. The results indicate that subsurface processes were especially strong in the summer of 2014 and they led to positive sea surface salinity anomalies in the central equatorial Pacific. The positive sea surface salinity anomalies induced a westward displacement of the sea surface salinity front that represents the eastern boundary of the western Pacific warm pool, preventing the warm surface water from shifting eastward as seen in a typical El Niño event. In the meantime, more salty water was transported equatorward by a strengthening subtropical cell in the South Pacific. The enhanced subsurface processes in the central equatorial Pacific conveyed the salinity anomalies of subtropical origin to the sea surface and were largely responsible for the sea surface salinity variability but had less impacts on sea surface temperature during the 2014/15 failed El Niño, suggesting some potential advantage of ocean salinity in the El Niño-Southern Oscillation prediction.
Nie, Xunwei; Gao, Shan; Wang, Fan; Chi, Jianwei; Qu, Tangdong (2019). Origins and pathways of the Pacific Equatorial Undercurrent identified by a simulated adjoint tracer, Journal of Geophysical Research: Oceans, 10.1029/2018JC014212.
Formatted Citation: Nie, X., S. Gao, F. Wang, J. Chi, and T. Qu, 2019: Origins and pathways of the Pacific Equatorial Undercurrent identified by a simulated adjoint tracer. J. Geophys. Res. Ocean., 0(ja), doi:10.1029/2018JC014212
Abstract: The origins and pathways of the Pacific Equatorial Undercurrent (EUC) are investigated using a simulated adjoint tracer of the consortium Estimating the Circulation & Climate of the Ocean (ECCO). The main source waters of the EUC, as well as their transit time and contributions, are identified. The zonal variability of the EUC water composition and the contributions from different pathways are also estimated. Results show that the ratio of the EUC water coming from the tropics to that from extratropics is relatively stable (1 versus 4) along the equator, except in the western Pacific where extratropical water is more dominant. The main body of extratropical water within the EUC are transported through the western boundary pathways (WBPs), while the percent transported via the interior pathways (IPs) gradually increases toward the east. Tropical water merges into the EUC mainly through the Tropical Cells (TCs) with a larger portion through the northern side of the equator.
Forget, Gaël; Ferreira, David (2019). Global ocean heat transport dominated by heat export from the tropical Pacific, Nature Geoscience, 1, 10.1038/s41561-019-0333-7.
Title: Global ocean heat transport dominated by heat export from the tropical Pacific
Type: Journal Article
Publication: Nature Geoscience
Author(s): Forget, Gaël; Ferreira, David
Year: 2019
Formatted Citation: Forget, G., and D. Ferreira, 2019: Global ocean heat transport dominated by heat export from the tropical Pacific. Nature Geoscience, 1, doi:10.1038/s41561-019-0333-7
Abstract: Heat redistribution is one of the main mechanisms by which oceans regulate Earth's climate. Analyses of ocean heat transport tend to emphasize global-scale seawater pathways and concepts such as the great ocean conveyor belt. However, it is the divergence or convergence of heat transport within an oceanic region, rather than the origin or destination of seawater transiting through that region, that is most immediately relevant to Earth's heat budget. Here we use a recent gridded estimate of ocean heat transport to reveal the net effect on Earth's heat budget, the 'effective' ocean heat transport, by removing internal ocean heat loops that have obscured the interpretation of measurements. The result demonstrates the overwhelming predominance of the tropical Pacific, which exports four times as much heat as is imported in the Atlantic and Arctic. It also highlights the unique ability of the Atlantic and Indian oceans to transport heat across the Equator-Northward and Southward, respectively. However, effective inter-ocean heat transports are smaller than expected, suggesting that global-scale seawater pathways play only a minor role in Earth's heat budget.
Keywords: Climate and Earth system modelling, Physical oceanography
Heimbach, Patrick; Fukumori, Ichiro; Hill, Christopher N.; Ponte, Rui M.; Stammer, Detlef; Wunsch, Carl; Campin, Jean-Michel; Cornuelle, Bruce; Fenty, Ian; Forget, Gaël; Köhl, Armin; Mazloff, Matthew; Menemenlis, Dimitris; Nguyen, An T.; Piecuch, Christopher; Trossman, David; Verdy, Ariane; Wang, Ou; Zhang, Hong (2019). Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates, Frontiers in Marine Science (6), 55, 10.3389/fmars.2019.00055.
Title: Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates
Type: Journal Article
Publication: Frontiers in Marine Science
Author(s): Heimbach, Patrick; Fukumori, Ichiro; Hill, Christopher N.; Ponte, Rui M.; Stammer, Detlef; Wunsch, Carl; Campin, Jean-Michel; Cornuelle, Bruce; Fenty, Ian; Forget, Gaël; Köhl, Armin; Mazloff, Matthew; Menemenlis, Dimitris; Nguyen, An T.; Piecuch, Christopher; Trossman, David; Verdy, Ariane; Wang, Ou; Zhang, Hong
Year: 2019
Formatted Citation: Heimbach, P. and Coauthors, 2019: Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates. Frontiers in Marine Science, 6, 55, doi:10.3389/fmars.2019.00055
Abstract: In 1999, the consortium for Estimating the Circulation and Climate of the Ocean (ECCO) set out to synthesize the hydrographic data collected by the World Ocean Circulation Experiment (WOCE) and satellite sea surface height measurements into a complete and coherent description of the ocean afforded by an ocean general circulation model. Twenty years later, the versatility of ECCO's estimation framework enables production of global and regional ocean and sea-ice state estimates that incorporate not only the initial suite of data and its successors, but nearly all data streams available today. New observations include measurements from Argo floats, marine mammal-based hydrography, satellite retrievals of ocean bottom pressure and sea surface salinity, and ice-tethered profiler data in polar regions. The framework also produces improved estimates of uncertain inputs, including initial conditions, surface atmospheric state variables, and mixing parameters. The freely available state estimates and related efforts are property-conserving, allowing closed budget calculations that are a requisite to detect, quantify, and understand the evolution of climate-relevant signals as mandated by the Coupled Model Intercomparison Project Phase 6 (CMIP6) protocol. The solutions can be reproduced by users through provision of the underlying modeling and assimilation machinery. Regional efforts have spun off that offer increased spatial resolution to better resolve relevant processes. Emerging foci of ECCO are on global sea level change, in particular contributions from polar ice sheets, and the increased use of biogeochemical and ecosystem data to constrain global cycles of carbon, nitrogen and oxygen. Challenges in the coming decade include provision of uncertainties, informing observing system design, globally increased resolution, and moving toward coupled Earth system estimation with consistent momentum, heat and freshwater fluxes between the ocean, atmosphere, cryosphere and land.
Keywords: Adjoint method, ECCO, Ocean circulation and climate, coupled Earth system data assimilation, global ocean inverse modeling, ocean observations, optimal state and parameter estimation
Formatted Citation: Wu, F., P. Cornillon, L. Guan, and K. Kilpatrick, 2019: Long-Term Variations in the Pixel-to-Pixel Variability of NOAA AVHRR SST Fields from 1982 to 2015. Remote Sensing, 11(7), 844, doi:10.3390/rs11070844
Abstract: Sea surface temperature (SST) fields obtained from the series of space-borne five-channel Advanced Very High Resolution Radiometers (AVHRRs) provide the longest continuous time series of global SST available to date (1981-present). As a result, these data have been used for many studies and significant effort has been devoted to their careful calibration in an effort to provide a climate quality data record. However, little attention has been given to the local precision of the SST retrievals obtained from these instruments, which we refer to as the pixel-to-pixel (p2p) variability, a characteristic important in the ability to resolve structures such as ocean fronts characterized by small gradients in the SST field. In this study, the p2p variability is estimated for Level-2 SST fields obtained with the Pathfinder retrieval algorithm for AVHRRs on NOAA-07, 9, 11, 12 and 14-19. These estimates are stratified by year, season, day/night and along-scan/along-track. The overall variability ranges from 0.10 K to 0.21 K. For each satellite, the along-scan variability is between 10 and 20% smaller than the along-track variability (except for NOAA-16 nighttime for which it is approximately 30% smaller) and the summer and fall σ s are between 10 and 15% smaller than the winter and spring σ s. The differences between along-track and along-scan are attributed to the way in which the instrument has been calibrated. The seasonal differences result from the T 4 − T 5 term in the Pathfinder retrieval algorithm. This term is shown to be a major contributor to the p2p variability and it is shown that its impact could be substantially reduced without a deleterious effect on the overall p2p σ of the resulting products by spatially averaging it as part of the retrieval process. The AVHRR/3s (NOAA-15 through 19) were found to be relatively stable with trends in the p2p variability of at most 0.015 K/decade.
Xi, Hui; Zhang, Zizhan; Lu, Yang; Li, Yan (2019). Long-Term and Interannual Variation of the Steric Sea Level in the South China Sea and the Connection with ENSO, Journal of Coastal Research, 10.2112/JCOASTRES-D-18-00080.1.
Title: Long-Term and Interannual Variation of the Steric Sea Level in the South China Sea and the Connection with ENSO
Type: Journal Article
Publication: Journal of Coastal Research
Author(s): Xi, Hui; Zhang, Zizhan; Lu, Yang; Li, Yan
Year: 2019
Formatted Citation: Xi, H., Z. Zhang, Y. Lu, and Y. Li, 2019: Long-Term and Interannual Variation of the Steric Sea Level in the South China Sea and the Connection with ENSO. Journal of Coastal Research, doi:10.2112/JCOASTRES-D-18-00080.1
Wang, Jinbo; Fu, Lee-Lueng; Torres, Hector S.; Chen, Shuiming; Qiu, Bo; Menemenlis, Dimitris (2019). On the Spatial Scales to be Resolved by the Surface Water and Ocean Topography Ka-Band Radar Interferometer, Journal of Atmospheric and Oceanic Technology, 1 (36), 87-99, 10.1175/JTECH-D-18-0119.1.
Formatted Citation: Wang, J., L. Fu, H. S. Torres, S. Chen, B. Qiu, and D. Menemenlis, 2019: On the Spatial Scales to be Resolved by the Surface Water and Ocean Topography Ka-Band Radar Interferometer. Journal of Atmospheric and Oceanic Technology, 36(1), 87-99, doi:10.1175/JTECH-D-18-0119.1
Chereskin, Teresa K.; Rocha, Cesar B.; Gille, Sarah T.; Menemenlis, Dimitris; Passaro, Marcello (2019). Characterizing the Transition From Balanced to Unbalanced Motions in the Southern California Current, Journal of Geophysical Research: Oceans, 3 (124), 2088-2109, 10.1029/2018JC014583.
Title: Characterizing the Transition From Balanced to Unbalanced Motions in the Southern California Current
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Chereskin, Teresa K.; Rocha, Cesar B.; Gille, Sarah T.; Menemenlis, Dimitris; Passaro, Marcello
Year: 2019
Formatted Citation: Chereskin, T. K., C. B. Rocha, S. T. Gille, D. Menemenlis, and M. Passaro, 2019: Characterizing the Transition From Balanced to Unbalanced Motions in the Southern California Current. J. Geophys. Res. Ocean., 124(3), 2088-2109, doi:10.1029/2018JC014583
Sinha, Anirban; Balwada, Dhruv; Tarshish, Nathaniel; Abernathey, Ryan (2019). Modulation of Lateral Transport by Submesoscale Flows and Inertia-Gravity Waves, Journal of Advances in Modeling Earth Systems, 2018MS001508, 10.1029/2018MS001508.
Title: Modulation of Lateral Transport by Submesoscale Flows and Inertia-Gravity Waves
Type: Journal Article
Publication: Journal of Advances in Modeling Earth Systems
Author(s): Sinha, Anirban; Balwada, Dhruv; Tarshish, Nathaniel; Abernathey, Ryan
Year: 2019
Formatted Citation: Sinha, A., D. Balwada, N. Tarshish, and R. Abernathey, 2019: Modulation of Lateral Transport by Submesoscale Flows and Inertia-Gravity Waves. Journal of Advances in Modeling Earth Systems, 2018MS001508, doi:10.1029/2018MS001508
Sinha, Anirban (2019). Temporal Variability in Ocean Mesoscale and Submesoscale Turbulence.
Title: Temporal Variability in Ocean Mesoscale and Submesoscale Turbulence
Type: Thesis
Publication:
Author(s): Sinha, Anirban
Year: 2019
Formatted Citation: Sinha, A., 2019: Temporal Variability in Ocean Mesoscale and Submesoscale Turbulence.
Abstract:
Keywords:
ECCO Products Used: LLC_hires
URL:
Other URLs:
Wang, Jinbo; Fu, Lee-Lueng (2019). On the Long-Wavelength Validation of the Swot Karin Measurement, Journal of Atmospheric and Oceanic Technology, 10.1175/jtech-d-18-0148.1.
Title: On the Long-Wavelength Validation of the Swot Karin Measurement
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Wang, Jinbo; Fu, Lee-Lueng
Year: 2019
Formatted Citation: Wang, J., and L. Fu, 2019: On the Long-Wavelength Validation of the Swot Karin Measurement. Journal of Atmospheric and Oceanic Technology, doi:10.1175/jtech-d-18-0148.1
Formatted Citation: Ardhuin, F. and Coauthors, 2019: SKIM, a Candidate Satellite Mission Exploring Global Ocean Currents and Waves. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00209
Yu, Xiaolong; Naveira Garabato, Alberto C.; Martin, Adrian P; Buckingham, Christian E; Brannigan, Liam; Su, Zhan (2019). An Annual Cycle of Submesoscale Vertical Flow and Restratification in the Upper Ocean, Journal of Physical Oceanography, JPO-D-18-0253.1, 10.1175/JPO-D-18-0253.1.
Title: An Annual Cycle of Submesoscale Vertical Flow and Restratification in the Upper Ocean
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Yu, Xiaolong; Naveira Garabato, Alberto C.; Martin, Adrian P; Buckingham, Christian E; Brannigan, Liam; Su, Zhan
Year: 2019
Formatted Citation: Yu, X., A. C. Naveira Garabato, A. P. Martin, C. E. Buckingham, L. Brannigan, and Z. Su, 2019: An Annual Cycle of Submesoscale Vertical Flow and Restratification in the Upper Ocean. Journal of Physical Oceanography, JPO-D-18-0253.1, doi:10.1175/JPO-D-18-0253.1
Formatted Citation: Zhao, Z., J. Wang, D. Menemenlis, L. Fu, S. Chen, and B. Qiu, 2019: Decomposition of the multimodal multidirectional M 2 internal tide field. Journal of Atmospheric and Oceanic Technology, JTECH-D-19-0022.1, doi:10.1175/JTECH-D-19-0022.1
Ridenour, Natasha A.; Hu, Xianmin; Sydor, Kevin; Myers, Paul G.; Barber, David G. (2019). Revisiting the Circulation of Hudson Bay: Evidence for a Seasonal Pattern, Geophysical Research Letters, 7 (46), 3891-3899, 10.1029/2019GL082344.
Title: Revisiting the Circulation of Hudson Bay: Evidence for a Seasonal Pattern
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Ridenour, Natasha A.; Hu, Xianmin; Sydor, Kevin; Myers, Paul G.; Barber, David G.
Year: 2019
Formatted Citation: Ridenour, N. A., X. Hu, K. Sydor, P. G. Myers, and D. G. Barber, 2019: Revisiting the Circulation of Hudson Bay: Evidence for a Seasonal Pattern. Geophys. Res. Lett., 46(7), 3891-3899, doi:10.1029/2019GL082344
Abstract: The Hudson Bay Complex (HBC) is the outlet for many Canadian rivers, receiving roughly 900 km3/year of river runoff. Historically, studies found a consistent cyclonic flow year-round in Hudson Bay, due to the geostrophic boundary current induced by river discharge and cyclonic wind forcing that was supported by available observations at that time. Using a high resolution ocean general circulation model, we show that, in summer, the mean circulation is not cyclonic, but consists of multiple small cyclonic and anticyclonic features, with the mean flow directed through the center of the bay. Absolute Dynamic Topography (ADT) and velocity observations also show this seasonal flow pattern. We find that this summer circulation is driven by geostrophic currents, generated by steric height gradients which are induced by increased river discharge during the spring freshet, and reinforced by anticyclonic seasonal wind patterns.
Mikolaj, M.; Reich, M.; Güntner, A. (2019). Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction-Induced Uncertainty, Journal of Geophysical Research: Solid Earth, 10.1029/2018JB016682.
Title: Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction-Induced Uncertainty
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Mikolaj, M.; Reich, M.; Güntner, A.
Year: 2019
Formatted Citation: Mikolaj, M., M. Reich, and A. Güntner, 2019: Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction-Induced Uncertainty. Journal of Geophysical Research: Solid Earth, doi:10.1029/2018JB016682
Abstract: Terrestrial gravimetry is increasingly used to monitor mass transport processes in geophysics boosted by the ongoing technological development of instruments. Resolving a particular phenomenon of interest, however, requires a set of gravity corrections of which the uncertainties have not been addressed up to now. In this study, we quantify the time domain uncertainty of tide, global atmospheric, large-scale hydrological, and non-tidal ocean loading corrections. The uncertainty is assessed by comparing the majority of available global models for a suite of sites worldwide . The average uncertainty expressed as root-mean-square error equals 5.1 nm/s2, discounting local hydrology or air pressure. The correction-induced uncertainty of gravity changes over various time periods of interest ranges from 0.6 nm/s2 for hours up to a maximum of 6.7 nm/s2 for six months. The corrections are shown to be significant and should be applied for most geophysical applications of terrestrial gravimetry. From a statistical point of view however, resolving subtle gravity effects in the order of few nm/s2 is challenged by the uncertainty of the corrections. Many scientist are exploring ways to benefit from gravity measurements in fields of high societal relevance such as monitoring of volcanoes or measuring the amount of water in underground. Any application of such new methods, however, requires careful preparation of the gravity measurements. The intention of the preparation process is to ensure that the measurements do not contain information about processes which are not of interest. For that reason, the influence of atmosphere, ocean, tides and hydrology needs to be reduced from the gravity. In this study, we investigate how this reduction process influences the quality of the measurement. We found that the precision degrades especially owing to the hydrology. The ocean plays an important role at sites close to the coast and the atmosphere at sites located in mountains. The overall errors of the reductions may complicate a reliable use of gravity measurements in certain studies focusing on very small signals. Nevertheless, the precision of gravity reductions alone does not obstruct a meaningful use of gravity measurements in most research fields. Details specifying the reduction precision are provided in this study allowing scientist dealing with gravity measurements to decide if their signal of interest can be reliably resolved. Global-scale uncertainty assessment of tidal, oceanic, large-scale hydrological and atmospheric corrections for terrestrial gravimetry Resolving subtle gravity signals in the order of few nm/s2 is challenged by the statistical uncertainty of correction models Uncertainty computed for selected periods varies significantly with latitude and altitude of the gravi
Yang, Yang; Liang, X. San (2019). The intrinsic nonlinear multiscale interactions among the mean flow, low frequency variability and mesoscale eddies in the Kuroshio region, Science China Earth Sciences, 10.1007/s11430-018-9289-4.
Title: The intrinsic nonlinear multiscale interactions among the mean flow, low frequency variability and mesoscale eddies in the Kuroshio region
Type: Journal Article
Publication: Science China Earth Sciences
Author(s): Yang, Yang; Liang, X. San
Year: 2019
Formatted Citation: Yang, Y., and X. S. Liang, 2019: The intrinsic nonlinear multiscale interactions among the mean flow, low frequency variability and mesoscale eddies in the Kuroshio region. Science China Earth Sciences, doi:10.1007/s11430-018-9289-4
Doddridge, Edward W.; Meneghello, Gianluca; Marshall, John; Scott, Jeffery; Lique, Camille (2019). A Three-way Balance in The Beaufort Gyre: The Ice-Ocean Governor, Wind Stress, and Eddy Diffusivity, Journal of Geophysical Research: Oceans, 10.1029/2018JC014897.
Formatted Citation: Doddridge, E. W., G. Meneghello, J. Marshall, J. Scott, and C. Lique, 2019: A Three-way Balance in The Beaufort Gyre: The Ice-Ocean Governor, Wind Stress, and Eddy Diffusivity. J. Geophys. Res. Ocean., doi:10.1029/2018JC014897
Abstract: The Beaufort Gyre (BG) is a large anticyclonic circulation in the Arctic Ocean. Its strength is directly related to the halocline depth, and therefore also to the storage of freshwater. It has recently been proposed that the equilibrium state of the BG is set by the Ice-Ocean Governor, a negative feedback between surface currents and ice-ocean stress, rather than a balance between lateral mesoscale eddy fluxes and surface Ekman pumping. However, mesoscale eddies are present in the Arctic Ocean; it is therefore important to extend the Ice-Ocean Governor theory to include lateral fluxes due to mesoscale eddies. Here, a non-linear ordinary differential equation is derived that represents the effects of wind stress, the Ice-Ocean Governor, and eddy fluxes. Equilibrium and time-varying solutions to this three-way balance equation are obtained and shown to closely match the output from a hierarchy of numerical simulations, indicating that the analytical model represents the processes controlling BG equilibration. The equilibration timescale derived from this three-way balance is faster than the eddy equilibration timescale and slower than the Ice-Ocean Governor equilibration timescales for most values of eddy diffusivity. The sensitivity of the BG equilibrium depth to changes in eddy diffusivity and the presence of the Ice-Ocean Governor is also explored. These results show that predicting the response of the BG to changing surface forcing and sea ice conditions requires faithfully capturing the three-way balance between the Ice-Ocean Governor, wind stress, and eddy fluxes.
Wei, Jianfen; Zhang, Xiangdong; Wang, Zhaomin (2019). Reexamination of Fram Strait sea ice export and its role in recently accelerated Arctic sea ice retreat, Climate Dynamics, 10.1007/s00382-019-04741-0.
Formatted Citation: Wei, J., X. Zhang, and Z. Wang, 2019: Reexamination of Fram Strait sea ice export and its role in recently accelerated Arctic sea ice retreat. Climate Dynamics, doi:10.1007/s00382-019-04741-0
Abstract:
Keywords: Fram Strait, MITgcm-ECCO2, Regime shift, Sea ice export
Title: Polar climate system modeling in China: Recent progress and future challenges
Type: Journal Article
Publication: Science China Earth Sciences
Author(s): WANG, Zhaomin; CHEN, Dake
Year: 2019
Formatted Citation: WANG, Z., and D. CHEN, 2019: Polar climate system modeling in China: Recent progress and future challenges. Science China Earth Sciences, doi:https://doi.org/10.1007/s11430-018-9355-2
Formatted Citation: Yang, Q., L. Mu, X. Wu, J. Liu, F. Zheng, J. Zhang, and C. Li, 2019: Improving Arctic sea ice seasonal outlook by ensemble prediction using an ice-ocean model. Atmospheric Research, 227, 14-23, doi:10.1016/j.atmosres.2019.04.021
Jyoti, J.; Swapna, P.; Krishnan, R.; Naidu, C. V. (2019). Pacific modulation of accelerated south Indian Ocean sea level rise during the early 21st Century, Climate Dynamics, https://doi.org/10.1007/s00382-019-04795-0.
Title: Pacific modulation of accelerated south Indian Ocean sea level rise during the early 21st Century
Type: Journal Article
Publication: Climate Dynamics
Author(s): Jyoti, J.; Swapna, P.; Krishnan, R.; Naidu, C. V.
Year: 2019
Formatted Citation: Jyoti, J., P. Swapna, R. Krishnan, and C. V. Naidu, 2019: Pacific modulation of accelerated south Indian Ocean sea level rise during the early 21st Century. Climate Dynamics, doi:https://doi.org/10.1007/s00382-019-04795-0
Yang, Shengmu; Xing, Jiuxing; Sheng, Jinyu; Chen, Shengli; Chen, Daoyi (2019). A process study of interactions between a warm eddy and the Kuroshio Current in Luzon Strait: The fate of eddies, Journal of Marine Systems, 10.1016/j.jmarsys.2019.02.009.
Formatted Citation: Yang, S., J. Xing, J. Sheng, S. Chen, and D. Chen, 2019: A process study of interactions between a warm eddy and the Kuroshio Current in Luzon Strait: The fate of eddies. Journal of Marine Systems, doi:10.1016/j.jmarsys.2019.02.009
Abstract: Satellite observations reveal many mesoscale eddies in the West Pacific Ocean (WPO) that propagate westwards and eventually interact with the Kuroshio Current. Examination of global ocean and sea ice reanalysis data in years 2008-2015 suggests trajectories of these mesoscale eddies over the Kuroshio zone can be categorized into three different patterns: ~63% of mesoscale eddies dissipating during the eddy-current interaction, ~33% moving to the north along the Kuroshio and only ~4% passing through the Kuroshio and Luzon Strait (LS) to enter to the South China Sea (SCS). A three-dimensional ocean circulation model based on the MIT General Circulation Model (MITgcm) is used to study the evolution of a westward propagating mesoscale eddy during the eddy-current interaction. Thirteen numerical experiments are conducted with the circulation model driven by currents specified at the southern and northern open boundaries to represent the influence of the Kuroshio. A mesoscale eddy is initialized to the east of the Kuroshio and the model is integrated for 70 days in each experiment. Model results suggest that the northward-flowing Kuroshio Current and the seamount topography within LS form a barrier for the westward propagating eddies to enter the South China Sea (SCS). Non-linear interactions between the Kuroshio Current, local topography and westward propagating mesoscale eddies can generate localized eddies in LS which could be shed into the SCS. Furthermore, the eddy-current interaction is found to be one of mechanisms for generating a multi-eddy structure in LS region.
Keywords: Eddy-current interaction, Luzon Strait, Mesoscale eddies, Numerical model, Process study, The Kuroshio Current
Zhang, Y.; Guan, Y. P. (2019). Striations in Marginal Seas and the Mediterranean Sea, Geophysical Research Letters, 5 (46), https://doi.org/10.1029/2018GL081050.
Title: Striations in Marginal Seas and the Mediterranean Sea
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Zhang, Y.; Guan, Y. P.
Year: 2019
Formatted Citation: Zhang, Y., and Y. P. Guan, 2019: Striations in Marginal Seas and the Mediterranean Sea. Geophys. Res. Lett., 46(5), doi:https://doi.org/10.1029/2018GL081050
Hutter, Nils; Zampieri, Lorenzo; Losch, Martin (2019). Leads and ridges in Arctic sea ice from RGPS data and a new tracking algorithm, Cryosphere, 10.5194/tc-13-627-2019.
Title: Leads and ridges in Arctic sea ice from RGPS data and a new tracking algorithm
Type: Journal Article
Publication: Cryosphere
Author(s): Hutter, Nils; Zampieri, Lorenzo; Losch, Martin
Year: 2019
Formatted Citation: Hutter, N., L. Zampieri, and M. Losch, 2019: Leads and ridges in Arctic sea ice from RGPS data and a new tracking algorithm. Cryosphere, doi:10.5194/tc-13-627-2019
Abstract: Leads and pressure ridges are dominant features of the Arctic sea ice cover. Not only do they affect heat loss and surface drag, but also provide insight into the underlying physics of sea ice deformation. Due to their elongated shape they are referred as Linear Kinematic Features (LKFs). This paper introduces two methods that detect and track LKFs in sea ice deformation data and establish an LKF data set for the entire observing period of the RADARSAT Geophysical Processor System (RGPS). Both algorithms are available as open-source code and applicable to any gridded sea-ice drift and deformation data. The LKF detection algorithm classifies pixels with higher deformation rates compared to the immediate environment as LKF pixels, divides the binary LKF map into small segments, and re-connects multiple segments into individual LKFs based their distance and orientation relative to each other. The tracking algorithm uses sea-ice drift information to estimate a first guess of LKF distribution and identifies tracked features by the degree of overlap between detected features and the first guess. An optimization of the parameters of both algorithms is presented, as well as an extensive evaluation of both algorithms against hand-picked features in a reference data set. An LKF data set is derived from RGPS deformation data for the years from 1996 to 2008 that enables a comprehensive description of LKFs. LKF densities and LKF intersection angles derived from this data set agree well with previous estimates. Further, a power-law distribution of LKF length, an exponential distribution of LKF lifetimes, and a strong link to atmospheric drivers, here Arctic cyclones, is derived from the data set. Both algorithms are applied to output of a numerical sea-ice model to compare the LKF intersection angles in a high-resolution Arctic sea-ice simulation with the LKF data set.
Title: The export flux of particulate organic carbon derived from 210 Po/ 210 Pb disequilibria along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise
Formatted Citation: Tang, Y., N. Lemaitre, M. Castrillejo, M. Roca-Martí, P. Masqué, and G. Stewart, 2019: The export flux of particulate organic carbon derived from 210 Po/ 210 Pb disequilibria along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise. Biogeosciences, doi:10.5194/bg-16-309-2019
Abstract: The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May-June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. Vertical advection was incorporated into one version of the model using time-averaged vertical velocity, which had substantial variance. This resulted in large uncertainties for the 210Po export flux in this model, suggesting that those calculations of 210Po export fluxes should be used with great care. Despite the large uncertainties, there is no question that the deficits of 210Po in the Iberian Basin and at the Greenland Shelf have been strongly affected by vertical advection. Using the export flux of 210Po and the particulate organic carbon (POC) to 210Po ratio of total (>1µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10mmolCm−2d−1, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency <1%-15%), but relatively high export efficiencies were seen in the basins where diatoms dominated the phytoplankton community. The particularly low export efficiencies in the Iberian Basin, on the other hand, were explained by the dominance of smaller phytoplankton, such as cyanobacteria or coccolithophores. POC fluxes estimated from the 210Po∕210Pb and 234Th∕238U disequilibria agreed within a factor of 3 along the transect, with higher POC estimates generally derived from 234Th. The differences were attributed to integration timescales and the history of bloom events.
LIANG, QI; ZHOU, CHUNXIA; HOWAT, IAN M.; JEONG, SEONGSU; LIU, RUIXI; CHEN, YIMING (2019). Ice flow variations at Polar Record Glacier, East Antarctica, Journal of Glaciology (65).
Title: Ice flow variations at Polar Record Glacier, East Antarctica
Type: Journal Article
Publication: Journal of Glaciology
Author(s): LIANG, QI; ZHOU, CHUNXIA; HOWAT, IAN M.; JEONG, SEONGSU; LIU, RUIXI; CHEN, YIMING
Year: 2019
Formatted Citation: LIANG, Q., C. ZHOU, I. M. HOWAT, S. JEONG, R. LIU, and Y. CHEN, 2019: Ice flow variations at Polar Record Glacier, East Antarctica. Journal of Glaciology, 65, https://doi.org/10.1017/jog.2019.6%0A
Nardini, Pascal; Böttinger, Michael; Scheuermann, Gerik; Siegfried, Lydia; Schmidt, Martin; Mohrholz, Volker; Pogrzeba, Hans (2019). The tropical-subtropical coupling in the Southeast Atlantic from the perspective of the northern Benguela upwelling system, PLoS ONE, 10.1371/journal.pone.0210083.
Formatted Citation: Nardini, P., M. Böttinger, G. Scheuermann, L. Siegfried, M. Schmidt, V. Mohrholz, and H. Pogrzeba, 2019: The tropical-subtropical coupling in the Southeast Atlantic from the perspective of the northern Benguela upwelling system. PLoS ONE, doi:10.1371/journal.pone.0210083
Gruszczynska, Marta; Rosat, Severine; Klos, Anna; Gruszczynski, Maciej; Bogusz, Janusz (2019). Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations, Geodynamics and Earth Tides Observations from Global to Micro Scale, 221-228, https://doi.org/10.1007/978-3-319-96277-1_17.
Formatted Citation: Gruszczynska, M., S. Rosat, A. Klos, M. Gruszczynski, and J. Bogusz, 2019: Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations. Geodynamics and Earth Tides Observations from Global to Micro Scale, Springer, 221-228, doi:https://doi.org/10.1007/978-3-319-96277-1_17
Klos, Anna; Gruszczynska, Marta; Bos, Machiel Simon; Boy, Jean-paul; Bogusz, Janusz (2019). Estimates of Vertical Velocity Errors for IGS ITRF2014 Stations by Applying the Improved Singular Spectrum Analysis Method and Environmental Loading Models, Geodynamics and Earth Tides Observations from Global to Micro Scale, 229-246, https://doi.org/10.1007/978-3-319-96277-1_18.
Title: Estimates of Vertical Velocity Errors for IGS ITRF2014 Stations by Applying the Improved Singular Spectrum Analysis Method and Environmental Loading Models
Type: Book Section
Publication: Geodynamics and Earth Tides Observations from Global to Micro Scale
Formatted Citation: Klos, A., M. Gruszczynska, M. S. Bos, J. Boy, and J. Bogusz, 2019: Estimates of Vertical Velocity Errors for IGS ITRF2014 Stations by Applying the Improved Singular Spectrum Analysis Method and Environmental Loading Models. Geodynamics and Earth Tides Observations from Global to Micro Scale, Springer, 229-246, doi:https://doi.org/10.1007/978-3-319-96277-1_18
Mikolaj, Michal; Güntner, Andreas; Brunini, Claudio; Wziontek, Hartmut; Gende, Mauricio; Schröder, Stephan; Cassino, Augusto M.; Pasquaré, Alfredo; Reich, Marvin; Hartmann, Anne; Oreiro, Fernando A.; Pendiuk, Jonathan; Guarracino, Luis; Antokoletz, Ezequiel D. (2019). Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata, Earth System Science Data Discussions, 10.5194/essd-2018-156.
Title: Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata
Type: Journal Article
Publication: Earth System Science Data Discussions
Author(s): Mikolaj, Michal; Güntner, Andreas; Brunini, Claudio; Wziontek, Hartmut; Gende, Mauricio; Schröder, Stephan; Cassino, Augusto M.; Pasquaré, Alfredo; Reich, Marvin; Hartmann, Anne; Oreiro, Fernando A.; Pendiuk, Jonathan; Guarracino, Luis; Antokoletz, Ezequiel D.
Year: 2019
Formatted Citation: Mikolaj, M. and Coauthors, 2019: Hydrometerological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata. Earth System Science Data Discussions, doi:10.5194/essd-2018-156
Abstract: Abstract. The Argentine-German Geodetic Observatory (AGGO) is one of the very few sites in the southern hemisphere equipped with a comprehensive cutting-edge geodetic instrumentation. The employed observation techniques are used for a wide range of geophysical applications. The presented multi-compartmental data set provides gravity time series and selected gravity models together with the hydrometeorological monitoring data of the observatory. These parameters are of great interest to the scientific community, e.g., for achieving accurate realization of terrestrial and celestial reference frames. Moreover, the availability of the hydrometeorological products is beneficial to inhabitants of the region as they allow for monitoring of environmental changes and natural hazards including extreme events. The hydrological data set is composed of time series of groundwater level, modelled and observed soil moisture content, soil temperature, and physical soil properties and aquifer properties. The meteorological time series include air temperature, humidity, pressure, wind speed, solar radiation, precipitation, and derived reference evapotranspiration. These data products are extended by gravity models of hydrological, oceanic, La Plata Estuary, and atmospheric effects. The quality of the provided meteorological time series is tested via comparison to the two closest WMO sites where data is available only in an inferior temporal resolution. The hydrological series are validated by comparing the respective forward-modelled gravity effects to independent gravity observations reduced up to a signal corresponding to local water storage variation. Most of the time series cover the time span between April 2016 and November 2018 with either no, or only few missing data points. The data set is available at https://doi.org/10.5880/GFZ.5.4.2018.001 (Mikolaj et al., 2018).
Manizza, Manfredi; Menemenlis, Dimitris; Zhang, Hong; Miller, Charles E. (2019). Modeling the Recent Changes in the Arctic Ocean CO 2 Sink (2006-2013), Global Biogeochemical Cycles, 10.1029/2018GB006070.
Title: Modeling the Recent Changes in the Arctic Ocean CO 2 Sink (2006-2013)
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): Manizza, Manfredi; Menemenlis, Dimitris; Zhang, Hong; Miller, Charles E.
Year: 2019
Formatted Citation: Manizza, M., D. Menemenlis, H. Zhang, and C. E. Miller, 2019: Modeling the Recent Changes in the Arctic Ocean CO 2 Sink (2006-2013). Global Biogeochemical Cycles, doi:10.1029/2018GB006070
Formatted Citation: Caputi, L. and Coauthors, 2019: Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems. Global Biogeochemical Cycles, doi:10.1029/2018GB006022
Abstract: Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment.
Keywords: iron response, meta-omics, species networks, system biology
Formatted Citation: Li, G., Y. Zhang, J. Xiao, X. Song, J. Abraham, L. Cheng, and J. Zhu, 2019: Examining the salinity change in the upper Pacific Ocean during the Argo period. Climate Dynamics, 53(9), 6055-6074, doi:10.1007/s00382-019-04912-z
Abstract: During the Argo period, the Pacific Ocean as well as the global oceans became saltier in the upper-200 m from 2005 to 2015, with a significant spatial variability. Using Argo-based observations and the Estimating the Circulation and Climate of the Ocean (ECCO), a salinity budget analysis in the upper 200 m was conducted to investigate what controls the recent observed salinity change in the Pacific Ocean. The results showed that the increasing salinity since 2005 was mainly caused by a reduction of surface precipitation. The ocean advection dampened the surface freshwater anomalies and rebuilt regional salinity balance. Both precipitation and advection are closely associated with the sea surface wind anomalies, suggesting the wind-driven changes in the ocean salinity field. A further analysis using an ocean objective analysis product and model simulations in addition to ECCO suggests that the recent salinity pattern since 2005 are related to the Interdecadal Pacific Oscillation (IPO). This study also highlights the strong regulation of the ocean salinity change by natural decadal variability in the climate system.
Carton, James A; Penny, Stephen G; Kalnay, Eugenia (2019). Temperature and Salinity Variability in the SODA3, ECCO4r3, and ORAS5 Ocean Reanalyses, 1993-2015, Journal of Climate, 8 (32), 2277-2293, 10.1175/JCLI-D-18-0605.1.
Title: Temperature and Salinity Variability in the SODA3, ECCO4r3, and ORAS5 Ocean Reanalyses, 1993-2015
Type: Journal Article
Publication: Journal of Climate
Author(s): Carton, James A; Penny, Stephen G; Kalnay, Eugenia
Year: 2019
Formatted Citation: Carton, J. A., S. G. Penny, and E. Kalnay, 2019: Temperature and Salinity Variability in the SODA3, ECCO4r3, and ORAS5 Ocean Reanalyses, 1993-2015. J. Clim., 32(8), 2277-2293, doi:10.1175/JCLI-D-18-0605.1
Abstract: This study extends recent ocean reanalysis comparisons to explore improvements to several next-generation products, the Simple Ocean Data Assimilation, version 3 (SODA3); the Estimating the Circulation and Climate of the Ocean, version 4, release 3 (ECCO4r3); and the Ocean Reanalysis System 5 (ORAS5), during their 23-yr period of overlap (1993?2015). The three reanalyses share similar historical hydrographic data, but the forcings, forward models, estimation algorithms, and bias correction methods are different. The study begins by comparing the reanalyses to independent analyses of historical SST, heat, and salt content, as well as examining the analysis-minus-observation misfits. While the misfits are generally small, they still reveal some systematic biases that are not present in the reference Hadley Center EN4 objective analysis. We next explore global trends in temperature averaged into three depth intervals: 0?300, 300?1000, and 1000?2000 m. We find considerable similarity in the spatial structure of the trends and their distribution among different ocean basins; however, the trends in global averages do differ by 30%?40%, which implies an equivalent level of disagreement in net surface heating rates. ECCO4r3 is distinct in having quite weak warming trends while ORAS5 has stronger trends that are noticeable in the deeper layers. To examine the performance of the reanalyses in the Arctic we explore representation of Atlantic Water variability on the Atlantic side of the Arctic and upper-halocline freshwater storage on the Pacific side of the Arctic. These comparisons are encouraging for the application of ocean reanalyses to track ocean climate variability and change at high northern latitudes.
Liu, Chao; Liang, Xinfeng; Ponte, Rui M; Vinogradova, Nadya; Wang, Ou (2019). Vertical redistribution of salt and layered changes in global ocean salinity, Nature Communications, 1 (10), 3445, 10.1038/s41467-019-11436-x.
Title: Vertical redistribution of salt and layered changes in global ocean salinity
Type: Journal Article
Publication: Nature Communications
Author(s): Liu, Chao; Liang, Xinfeng; Ponte, Rui M; Vinogradova, Nadya; Wang, Ou
Year: 2019
Formatted Citation: Liu, C., X. Liang, R. M. Ponte, N. Vinogradova, and O. Wang, 2019: Vertical redistribution of salt and layered changes in global ocean salinity. Nature Communications, 10(1), 3445, doi:10.1038/s41467-019-11436-x
Abstract: Salinity is an essential proxy for estimating the global net freshwater input into the ocean. Due to the limited spatial and temporal coverage of the existing salinity measurements, previous studies of global salinity changes focused mostly on the surface and upper oceans. Here, we examine global ocean salinity changes and ocean vertical salt fluxes over the full depth in a dynamically consistent and data-constrained ocean state estimate. The changes of the horizontally averaged salinity display a vertically layered structure, consistent with the profiles of the ocean vertical salt fluxes. For salinity changes in the relatively well-observed upper ocean, the contribution of vertical exchange of salt can be on the same order of the net surface freshwater input. The vertical redistribution of salt thus should be considered in inferring changes in global ocean salinity and the hydrological cycle from the surface and upper ocean measurements.
Piecuch, Christopher G; Thompson, Philip R; Ponte, Rui M; Merrifield, Mark A; Hamlington, Benjamin D (2019). What Caused Recent Shifts in Tropical Pacific Decadal Sea-Level Trends?, Journal of Geophysical Research: Oceans, 11 (124), 7575-7590, 10.1029/2019JC015339.
Title: What Caused Recent Shifts in Tropical Pacific Decadal Sea-Level Trends?
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Piecuch, Christopher G; Thompson, Philip R; Ponte, Rui M; Merrifield, Mark A; Hamlington, Benjamin D
Year: 2019
Formatted Citation: Piecuch, C. G., P. R. Thompson, R. M. Ponte, M. A. Merrifield, and B. D. Hamlington, 2019: What Caused Recent Shifts in Tropical Pacific Decadal Sea-Level Trends? J. Geophys. Res. Ocean., 124(11), 7575-7590, doi:10.1029/2019JC015339
Abstract: Satellite altimetry reveals substantial decadal variability in sea level ? across the tropical Pacific during 1993?2015. An ocean state estimate that faithfully reproduces the observations is used to elucidate the origin of these low-frequency tropical Pacific ? variations. Analysis of the hydrostatic equation reveals that recent decadal ? changes in the tropical Pacific are mainly thermosteric in nature, related to changes in upper-ocean heat content. A forcing experiment performed with the numerical model suggests that anomalous wind stress was an important driver of the relevant heat storage and thermosteric variation. Closed budget diagnostics further clarify that the wind-stress-related thermosteric ? variation resulted from the joint actions of large-scale ocean advection and local surface heat flux, such that advection controlled the budget over shorter, intraseasonal to interannual time scales, and local surface heat flux became increasingly influential at longer decadal periods. In particular, local surface heat flux was important in contributing to a recent reversal of decadal ? trends in the tropical Pacific. Contributions from local surface heat flux partly reflect damping latent heat flux tied to wind-stress-driven sea-surface-temperature variations.
Amin, Hadi; Sjöberg, Lars E.; Bagherbandi, Mohammad (2019). A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters, Journal of Geodesy, 10.1007/s00190-019-01293-3.
Title: A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Amin, Hadi; Sjöberg, Lars E.; Bagherbandi, Mohammad
Year: 2019
Formatted Citation: Amin, H., L. E. Sjöberg, and M. Bagherbandi, 2019: A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters. Journal of Geodesy, doi:10.1007/s00190-019-01293-3
Abstract: The geoid, according to the classical Gauss-Listing definition, is, among infinite equipotential surfaces of the Earth's gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth's global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth's gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.
Keywords: Geodetic reference system, Geoid potential W0, Global vertical datum, Mean Earth ellipsoid, Reference ellipsoid
ECCO Products Used:
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Asbjørnsen, Helene; Årthun, Marius; Skagseth, Øystein; Eldevik, Tor (2019). Mechanisms of Ocean Heat Anomalies in the Norwegian Sea, Journal of Geophysical Research: Oceans, 4 (124), 2908-2923, 10.1029/2018JC014649.
Title: Mechanisms of Ocean Heat Anomalies in the Norwegian Sea
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Asbjørnsen, Helene; Årthun, Marius; Skagseth, Øystein; Eldevik, Tor
Year: 2019
Formatted Citation: Asbjørnsen, H., M. Årthun, Ø. Skagseth, and T. Eldevik, 2019: Mechanisms of Ocean Heat Anomalies in the Norwegian Sea. J. Geophys. Res. Ocean., 124(4), 2908-2923, doi:10.1029/2018JC014649
Alexander-Astiz Le Bras, Isabela; Sonnewald, Maike; Toole, John M. (2019). A Barotropic Vorticity Budget for the Subtropical North Atlantic Based on Observations, Journal of Physical Oceanography, 11 (49), 2781-2797, 10.1175/JPO-D-19-0111.1.
Title: A Barotropic Vorticity Budget for the Subtropical North Atlantic Based on Observations
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Alexander-Astiz Le Bras, Isabela; Sonnewald, Maike; Toole, John M.
Year: 2019
Formatted Citation: Alexander-Astiz Le Bras, I., M. Sonnewald, and J. M. Toole, 2019: A Barotropic Vorticity Budget for the Subtropical North Atlantic Based on Observations. Journal of Physical Oceanography, 49(11), 2781-2797, doi:10.1175/JPO-D-19-0111.1
Abstract: To ground truth the large-scale dynamical balance of the North Atlantic subtropical gyre with observations, a barotropic vorticity budget is constructed in the ECCO state estimate and compared with hydrographic observations and wind stress data products. The hydrographic dataset at the center of this work is the A22 WOCE section, which lies along 66°W and creates a closed volume with the North and South American coasts to its west. The planetary vorticity flux across A22 is quantified, providing a metric for the net meridional flow in the western subtropical gyre. The wind stress forcing over the subtropical gyre to the west and east of the A22 section is calculated from several wind stress data products. These observational budget terms are found to be consistent with an approximate barotropic Sverdrup balance in the eastern subtropical gyre and are on the same order as budget terms in the ECCO state estimate. The ECCO vorticity budget is closed by bottom pressure torques in the western subtropical gyre, which is consistent with previous studies. In sum, the analysis provides observational ground truth for the North Atlantic subtropical vorticity balance and explores the seasonal variability of this balance for the first time using the ECCO state estimate. This balance is found to hold on monthly time scales in ECCO, suggesting that the integrated subtropical gyre responds to forcing through fast barotropic adjustment.
Title: Some Expectations for Submesoscale Sea Surface Height Variance Spectra
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Callies, Jörn; Wu, Weiguang
Year: 2019
Formatted Citation: Callies, J., and W. Wu, 2019: Some Expectations for Submesoscale Sea Surface Height Variance Spectra. Journal of Physical Oceanography, 49(9), 2271-2289, doi:10.1175/JPO-D-18-0272.1
Abstract: In anticipation of the Surface Water and Ocean Topography (SWOT) wide-swath altimetry mission, this study reviews expectations for sea surface height (SSH) variance spectra at wavelengths of 10-100 km. Kinetic energy spectra from in situ observations and numerical simulations indicate that SSH variance spectra associated with balanced flow drop off steeply with wavenumber, with at least the negative fourth power of the wavenumber. Such a steep drop-off implies that even drastic reductions in altimetry noise yield only a modest improvement in the resolution of balanced flow. This general expectation is made concrete by extrapolating SSH variance spectra from existing altimetry to submesoscales, the results of which suggest that in the extratropics (poleward of 20° latitude) SWOT will improve the resolution from currently about 100 km to a median of 51 or 74 km, depending on whether or not submesoscale balanced flows are energetic. Internal waves, in contrast to balanced flow, give rise to SSH variance spectra that drop off relatively gently with wavenumber, so SSH variance should become strongly dominated by internal waves in the submesoscale range. In situ observations of the internal-wave field suggest that the internal-wave signal accessible by SWOT will be largely dominated by internal tides. The internal-wave continuum is estimated to have a spectral level close to but somewhat lower than SWOT's expected noise level.
Kostov, Yavor; Johnson, Helen L.; Marshall, David P. (2019). AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms, Climate Dynamics, 7-8 (53), 4521-4537, 10.1007/s00382-019-04802-4.
Title: AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms
Type: Journal Article
Publication: Climate Dynamics
Author(s): Kostov, Yavor; Johnson, Helen L.; Marshall, David P.
Year: 2019
Formatted Citation: Kostov, Y., H. L. Johnson, and D. P. Marshall, 2019: AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms. Climate Dynamics, 53(7-8), 4521-4537, doi:10.1007/s00382-019-04802-4
Formatted Citation: Sutterley, T. C., and I. Velicogna, 2019: Improved Estimates of Geocenter Variability from Time-Variable Gravity and Ocean Model Outputs. Remote Sensing, 11(18), 2108, doi:10.3390/rs11182108
Abstract: Geocenter variations relate the motion of the Earth's center of mass with respect to its center of figure, and represent global-scale redistributions of the Earth's mass. We investigate different techniques for estimating of geocenter motion from combinations of time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On missions, and bottom pressure outputs from ocean models. Here, we provide self-consistent estimates of geocenter variability incorporating the effects of self-attraction and loading, and investigate the effect of uncertainties in atmospheric and oceanic variation. The effects of self-attraction and loading from changes in land water storage and ice mass change affect both the seasonality and long-term trend in geocenter position. Omitting the redistribution of sea level affects the average annual amplitudes of the x, y, and z components by 0.2, 0.1, and 0.3 mm, respectively, and affects geocenter trend estimates by 0.02, 0.04 and 0.05 mm/yr for the the x, y, and z components, respectively. Geocenter estimates from the GRACE Follow-On mission are consistent with estimates from the original GRACE mission.
Formatted Citation: Nakayama, Y. and Coauthors, 2019: Pathways of ocean heat towards Pine Island and Thwaites grounding lines. Scientific Reports, 9(1), 16649, doi:10.1038/s41598-019-53190-6
Schulze Chretien, Lena M.; Speer, Kevin (2019). A Deep Eastern Boundary Current in the Chile Basin, Journal of Geophysical Research: Oceans, 1 (124), 27-40, 10.1029/2018JC014400.
Title: A Deep Eastern Boundary Current in the Chile Basin
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Schulze Chretien, Lena M.; Speer, Kevin
Year: 2019
Formatted Citation: Schulze Chretien, L. M., and K. Speer, 2019: A Deep Eastern Boundary Current in the Chile Basin. J. Geophys. Res. Ocean., 124(1), 27-40, doi:10.1029/2018JC014400
Hu, Shijian; Zhang, Ying; Feng, Ming; Du, Yan; Sprintall, Janet; Wang, Fan; Hu, Dunxin; Xie, Qiang; Chai, Fei (2019). Interannual to Decadal Variability of Upper-Ocean Salinity in the Southern Indian Ocean and the Role of the Indonesian Throughflow, Journal of Climate, 19 (32), 6403-6421, 10.1175/JCLI-D-19-0056.1.
Formatted Citation: Hu, S. and Coauthors, 2019: Interannual to Decadal Variability of Upper-Ocean Salinity in the Southern Indian Ocean and the Role of the Indonesian Throughflow. J. Clim., 32(19), 6403-6421, doi:10.1175/JCLI-D-19-0056.1
Abstract: Variability of oceanic salinity, an indicator of the global hydrological cycle, plays an important role in the basin-scale ocean circulation. In this study, interannual to decadal variability of salinity in the upper layer of the Indian Ocean is investigated using Argo observations since 2004 and data assimilating model outputs (1992-2015). The southeastern Indian Ocean shows the strongest interannual to decadal variability of upper-ocean salinity in the Indian Ocean. Westward propagation of salinity anomalies along isopycnal surfaces is detected in the southern Indian Ocean and attributed to zonal salinity advection anomalies associated with the Indonesian Throughflow and the South Equatorial Current. Composite and salinity budget analyses show that horizontal advection is a major contributor to the interannual to decadal salinity variability of the southern Indian Ocean, and the local air-sea freshwater flux plays a secondary role. The Pacific decadal oscillation (PDO) and El Niño-Southern Oscillation (ENSO) modulate the salinity variability in the southeastern Indian Ocean, with low salinity anomalies occurring during the negative phases of the PDO and ENSO and high salinity anomalies during their positive phases. The Indonesian Throughflow plays an essential role in transmitting the PDO- and ENSO-related salinity signals into the Indian Ocean. A statistical model is proposed based on the PDO index, which successfully predicts the southeastern Indian Ocean salinity variability with a lead time of 10 months.
Jones, Daniel C.; Boland, Emma; Meijers, Andrew J.S.; Forget, Gael; Josey, Simon A.; Sallee, Jean-Baptiste; Shuckburgh, Emily (2019). Heat Distribution in the Southeast Pacific Is Only Weakly Sensitive to High-Latitude Heat Flux and Wind Stress, Journal of Geophysical Research: Oceans, 12 (124), 8647-8666, 10.1029/2019JC015460.
Title: Heat Distribution in the Southeast Pacific Is Only Weakly Sensitive to High-Latitude Heat Flux and Wind Stress
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Jones, Daniel C.; Boland, Emma; Meijers, Andrew J.S.; Forget, Gael; Josey, Simon A.; Sallee, Jean-Baptiste; Shuckburgh, Emily
Year: 2019
Formatted Citation: Jones, D. C., E. Boland, A. J. Meijers, G. Forget, S. A. Josey, J. Sallee, and E. Shuckburgh, 2019: Heat Distribution in the Southeast Pacific Is Only Weakly Sensitive to High-Latitude Heat Flux and Wind Stress. J. Geophys. Res. Ocean., 124(12), 8647-8666, doi:10.1029/2019JC015460
Jackson, L. C.; Dubois, C.; Forget, G.; Haines, K.; Harrison, M.; Iovino, D.; Köhl, A.; Mignac, D.; Masina, S.; Peterson, K. A.; Piecuch, C. G.; Roberts, C. D.; Robson, J.; Storto, A.; Toyoda, T.; Valdivieso, M.; Wilson, C.; Wang, Y.; Zuo, H. (2019). The Mean State and Variability of the North Atlantic Circulation: A Perspective From Ocean Reanalyses, Journal of Geophysical Research: Oceans, 12 (124), 9141-9170, 10.1029/2019JC015210.
Title: The Mean State and Variability of the North Atlantic Circulation: A Perspective From Ocean Reanalyses
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Jackson, L. C.; Dubois, C.; Forget, G.; Haines, K.; Harrison, M.; Iovino, D.; Köhl, A.; Mignac, D.; Masina, S.; Peterson, K. A.; Piecuch, C. G.; Roberts, C. D.; Robson, J.; Storto, A.; Toyoda, T.; Valdivieso, M.; Wilson, C.; Wang, Y.; Zuo, H.
Year: 2019
Formatted Citation: Jackson, L. C. and Coauthors, 2019: The Mean State and Variability of the North Atlantic Circulation: A Perspective From Ocean Reanalyses. J. Geophys. Res. Ocean., 124(12), 9141-9170, doi:10.1029/2019JC015210
Formatted Citation: Sun, Q., Y. Du, Y. Zhang, M. Feng, J. S. Chowdary, J. Chi, S. Qiu, and W. Yu, 2019: Evolution of Sea Surface Salinity Anomalies in the Southwestern Tropical Indian Ocean During 2010-2011 Influenced by a Negative IOD Event. J. Geophys. Res. Ocean., 124(5), 3428-3445, doi:10.1029/2018JC014580
Piecuch, C. G.; Calafat, F. M.; Dangendorf, S.; Jordà, G. (2019). The Ability of Barotropic Models to Simulate Historical Mean Sea Level Changes from Coastal Tide Gauge Data, Surveys in Geophysics, 6 (40), 1399-1435, 10.1007/s10712-019-09537-9.
Title: The Ability of Barotropic Models to Simulate Historical Mean Sea Level Changes from Coastal Tide Gauge Data
Type: Journal Article
Publication: Surveys in Geophysics
Author(s): Piecuch, C. G.; Calafat, F. M.; Dangendorf, S.; Jordà, G.
Year: 2019
Formatted Citation: Piecuch, C. G., F. M. Calafat, S. Dangendorf, and G. Jordà, 2019: The Ability of Barotropic Models to Simulate Historical Mean Sea Level Changes from Coastal Tide Gauge Data. Surveys in Geophysics, 40(6), 1399-1435, doi:10.1007/s10712-019-09537-9
Formatted Citation: Storto, A., A. Bonaduce, X. Feng, and C. Yang, 2019: Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales. Water, 11(10), 1987, doi:10.3390/w11101987
Abstract: Sea level has risen significantly in the recent decades and is expected to rise further based on recent climate projections. Ocean reanalyses that synthetize information from observing networks, dynamical ocean general circulation models, and atmospheric forcing data offer an attractive way to evaluate sea level trend and variability and partition the causes of such sea level changes at both global and regional scales. Here, we review recent utilization of reanalyses for steric sea level trend investigations. State-of-the-science ocean reanalysis products are then used to further infer steric sea level changes. In particular, we used an ensemble of centennial reanalyses at moderate spatial resolution (between 0.5 × 0.5 and 1 × 1 degree) and an ensemble of eddy-permitting reanalyses to quantify the trends and their uncertainty over the last century and the last two decades, respectively. All the datasets showed good performance in reproducing sea level changes. Centennial reanalyses reveal a 1900-2010 trend of steric sea level equal to 0.47 ± 0.04 mm year−1, in agreement with previous studies, with unprecedented rise since the mid-1990s. During the altimetry era, the latest vintage of reanalyses is shown to outperform the previous ones in terms of skill scores against the independent satellite data. They consistently reproduce global and regional upper ocean steric expansion and the association with climate variability, such as ENSO. However, the mass contribution to the global mean sea level rise is varying with products and its representability needs to be improved, as well as the contribution of deep and abyssal waters to the steric sea level rise. Similarly, high-resolution regional reanalyses for the European seas provide valuable information on sea level trends, their patterns, and their causes.
Wagner, Charlotte C.; Amos, Helen M.; Thackray, Colin P.; Zhang, Yanxu; Lundgren, Elizabeth W.; Forget, Gael; Friedman, Carey L.; Selin, Noelle E.; Lohmann, Rainer; Sunderland, Elsie M. (2019). A Global 3-D Ocean Model for PCBs: Benchmark Compounds for Understanding the Impacts of Global Change on Neutral Persistent Organic Pollutants, Global Biogeochemical Cycles, 3 (33), 469-481, 10.1029/2018GB006018.
Title: A Global 3-D Ocean Model for PCBs: Benchmark Compounds for Understanding the Impacts of Global Change on Neutral Persistent Organic Pollutants
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): Wagner, Charlotte C.; Amos, Helen M.; Thackray, Colin P.; Zhang, Yanxu; Lundgren, Elizabeth W.; Forget, Gael; Friedman, Carey L.; Selin, Noelle E.; Lohmann, Rainer; Sunderland, Elsie M.
Year: 2019
Formatted Citation: Wagner, C. C. and Coauthors, 2019: A Global 3-D Ocean Model for PCBs: Benchmark Compounds for Understanding the Impacts of Global Change on Neutral Persistent Organic Pollutants. Global Biogeochemical Cycles, 33(3), 469-481, doi:10.1029/2018GB006018
Ponsoni, Leandro; Massonnet, François; Fichefet, Thierry; Chevallier, Matthieu; Docquier, David (2019). On the timescales and length scales of the Arctic sea ice thickness anomalies: a study based on 14 reanalyses, The Cryosphere, 2 (13), 521-543, 10.5194/tc-13-521-2019.
Formatted Citation: Ponsoni, L., F. Massonnet, T. Fichefet, M. Chevallier, and D. Docquier, 2019: On the timescales and length scales of the Arctic sea ice thickness anomalies: a study based on 14 reanalyses. Cryosph., 13(2), 521-543, doi:10.5194/tc-13-521-2019
Zhang, Yanxu; Horowitz, Hannah; Wang, Jiancheng; Xie, Zhouqing; Kuss, Joachim; Soerensen, Anne L. (2019). A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry, Environmental Science & Technology, 9 (53), 5052-5061, 10.1021/acs.est.8b06205.
Title: A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry
Type: Journal Article
Publication: Environmental Science & Technology
Author(s): Zhang, Yanxu; Horowitz, Hannah; Wang, Jiancheng; Xie, Zhouqing; Kuss, Joachim; Soerensen, Anne L.
Year: 2019
Formatted Citation: Zhang, Y., H. Horowitz, J. Wang, Z. Xie, J. Kuss, and A. L. Soerensen, 2019: A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry. Environmental Science & Technology, 53(9), 5052-5061, doi:10.1021/acs.est.8b06205
Huang, Thomas; DeBellis, Maya; Fenty, Ian; Heimbach, Patrick; Jacob, Joseph C.; Wang, Ou; Yam, Elizabeth (2019). Analytics Center Framework for Estimating the Circulation and Climate of the Ocean, IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 5355-5358, 10.1109/IGARSS.2019.8897904.
Title: Analytics Center Framework for Estimating the Circulation and Climate of the Ocean
Type: Conference Proceedings
Publication: IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium
Author(s): Huang, Thomas; DeBellis, Maya; Fenty, Ian; Heimbach, Patrick; Jacob, Joseph C.; Wang, Ou; Yam, Elizabeth
Year: 2019
Formatted Citation: Huang, T., M. DeBellis, I. Fenty, P. Heimbach, J. C. Jacob, O. Wang, and E. Yam, 2019: Analytics Center Framework for Estimating the Circulation and Climate of the Ocean. IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium IEEE, 5355-5358 pp. doi:10.1109/IGARSS.2019.8897904.
Title: Atlantic Meridional Overturning Circulation: Observed Transport and Variability
Type: Journal Article
Publication: Frontiers in Marine Science
Author(s): Frajka-Williams, Eleanor; Ansorge, Isabelle J.; Baehr, Johanna; Bryden, Harry L.; Chidichimo, Maria Paz; Cunningham, Stuart A.; Danabasoglu, Gokhan; Dong, Shenfu; Donohue, Kathleen A.; Elipot, Shane; Heimbach, Patrick; Holliday, N. Penny; Hummels, Rebecca; Jackson, Laura C.; Karstensen, Johannes; Lankhorst, Matthias; Le Bras, Isabela A.; Lozier, M. Susan; McDonagh, Elaine L.; Meinen, Christopher S.; Mercier, Herlé; Moat, Bengamin I.; Perez, Renellys C.; Piecuch, Christopher G.; Rhein, Monika; Srokosz, Meric A.; Trenberth, Kevin E.; Bacon, Sheldon; Forget, Gael; Goni, Gustavo; Kieke, Dagmar; Koelling, Jannes; Lamont, Tarron; McCarthy, Gerard D.; Mertens, Christian; Send, Uwe; Smeed, David A.; Speich, Sabrina; van den Berg, Marcel; Volkov, Denis; Wilson, Chris
Year: 2019
Formatted Citation: Frajka-Williams, E. and Coauthors, 2019: Atlantic Meridional Overturning Circulation: Observed Transport and Variability. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00260
Formatted Citation: Storto, A. and Coauthors, 2019: Ocean Reanalyses: Recent Advances and Unsolved Challenges. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00418
Title: Observational Needs for Improving Ocean and Coupled Reanalysis, S2S Prediction, and Decadal Prediction
Type: Journal Article
Publication: Frontiers in Marine Science
Author(s): Penny, Stephen G.; Akella, Santha; Balmaseda, Magdalena A.; Browne, Philip; Carton, James A.; Chevallier, Matthieu; Counillon, Francois; Domingues, Catia; Frolov, Sergey; Heimbach, Patrick; Hogan, Patrick; Hoteit, Ibrahim; Iovino, Doroteaciro; Laloyaux, Patrick; Martin, Matthew J.; Masina, Simona; Moore, Andrew M.; de Rosnay, Patricia; Schepers, Dinand; Sloyan, Bernadette M.; Storto, Andrea; Subramanian, Aneesh; Nam, SungHyun; Vitart, Frederic; Yang, Chunxue; Fujii, Yosuke; Zuo, Hao; O'Kane, Terry; Sandery, Paul; Moore, Thomas; Chapman, Christopher C.
Year: 2019
Formatted Citation: Penny, S. G. and Coauthors, 2019: Observational Needs for Improving Ocean and Coupled Reanalysis, S2S Prediction, and Decadal Prediction. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00391
Formatted Citation: Vinogradova, N. and Coauthors, 2019: Satellite Salinity Observing System: Recent Discoveries and the Way Forward. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00243
Howe, Bruce M.; Miksis-Olds, Jennifer; Rehm, Eric; Sagen, Hanne; Worcester, Peter F.; Haralabus, Georgios (2019). Observing the Oceans Acoustically, Frontiers in Marine Science (6), 10.3389/fmars.2019.00426.
Author(s): Howe, Bruce M.; Miksis-Olds, Jennifer; Rehm, Eric; Sagen, Hanne; Worcester, Peter F.; Haralabus, Georgios
Year: 2019
Formatted Citation: Howe, B. M., J. Miksis-Olds, E. Rehm, H. Sagen, P. F. Worcester, and G. Haralabus, 2019: Observing the Oceans Acoustically. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00426
Title: Observing System Evaluation Based on Ocean Data Assimilation and Prediction Systems: On-Going Challenges and a Future Vision for Designing and Supporting Ocean Observational Networks
Formatted Citation: Fujii, Y. and Coauthors, 2019: Observing System Evaluation Based on Ocean Data Assimilation and Prediction Systems: On-Going Challenges and a Future Vision for Designing and Supporting Ocean Observational Networks. Frontiers in Marine Science, 6, doi:10.3389/fmars.2019.00417
Title: Arctic Ocean Freshwater Dynamics: Transient Response to Increasing River Runoff and Precipitation
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Brown, Nicola Jane; Nilsson, Johan; Pemberton, Per
Year: 2019
Formatted Citation: Brown, N. J., J. Nilsson, and P. Pemberton, 2019: Arctic Ocean Freshwater Dynamics: Transient Response to Increasing River Runoff and Precipitation. J. Geophys. Res. Ocean., 124(7), 5205-5219, doi:10.1029/2018JC014923
Author(s): Klein, Patrice; Lapeyre, Guillaume; Siegelman, Lia; Qiu, Bo; Fu, Lee-Lueng; Torres, Hector; Su, Zhan; Menemenlis, Dimitris; Le Gentil, Sylvie
Year: 2019
Formatted Citation: Klein, P. and Coauthors, 2019: Ocean-Scale Interactions From Space. Earth and Space Science, 2018EA000492, doi:10.1029/2018EA000492
Yu, Xiaolong; Ponte, Aurélien L.; Elipot, Shane; Menemenlis, Dimitris; Zaron, Edward D.; Abernathey, Ryan (2019). Surface Kinetic Energy Distributions in the Global Oceans From a High-Resolution Numerical Model and Surface Drifter Observations, Geophysical Research Letters, 16 (46), 9757-9766, 10.1029/2019GL083074.
Title: Surface Kinetic Energy Distributions in the Global Oceans From a High-Resolution Numerical Model and Surface Drifter Observations
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Yu, Xiaolong; Ponte, Aurélien L.; Elipot, Shane; Menemenlis, Dimitris; Zaron, Edward D.; Abernathey, Ryan
Year: 2019
Formatted Citation: Yu, X., A. L. Ponte, S. Elipot, D. Menemenlis, E. D. Zaron, and R. Abernathey, 2019: Surface Kinetic Energy Distributions in the Global Oceans From a High-Resolution Numerical Model and Surface Drifter Observations. Geophys. Res. Lett., 46(16), 9757-9766, doi:10.1029/2019GL083074
Pratt, Larry J.; Voet, Gunnar; Pacini, Astrid; Tan, Shuwen; Alford, Matthew H.; Carter, Glenn S.; Girton, James B.; Menemenlis, Dimitris (2019). Pacific Abyssal Transport and Mixing: Through the Samoan Passage versus around the Manihiki Plateau, Journal of Physical Oceanography, 6 (49), 1577-1592, 10.1175/JPO-D-18-0124.1.
Title: Pacific Abyssal Transport and Mixing: Through the Samoan Passage versus around the Manihiki Plateau
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Pratt, Larry J.; Voet, Gunnar; Pacini, Astrid; Tan, Shuwen; Alford, Matthew H.; Carter, Glenn S.; Girton, James B.; Menemenlis, Dimitris
Year: 2019
Formatted Citation: Pratt, L. J., G. Voet, A. Pacini, S. Tan, M. H. Alford, G. S. Carter, J. B. Girton, and D. Menemenlis, 2019: Pacific Abyssal Transport and Mixing: Through the Samoan Passage versus around the Manihiki Plateau. Journal of Physical Oceanography, 49(6), 1577-1592, doi:10.1175/JPO-D-18-0124.1
Abstract: The main source feeding the abyssal circulation of the North Pacific is the deep, northward flow of 5-6 Sverdrups (Sv; 1 Sv ≡ 10 6 m 3 s −1 ) through the Samoan Passage. A recent field campaign has shown that this flow is hydraulically controlled and that it experiences hydraulic jumps accompanied by strong mixing and dissipation concentrated near several deep sills. By our estimates, the diapycnal density flux associated with this mixing is considerably larger than the diapycnal flux across a typical isopycnal surface extending over the abyssal North Pacific. According to historical hydrographic observations, a second source of abyssal water for the North Pacific is 2.3-2.8 Sv of the dense flow that is diverted around the Manihiki Plateau to the east, bypassing the Samoan Passage. This bypass flow is not confined to a channel and is therefore less likely to experience the strong mixing that is associated with hydraulic transitions. The partitioning of flux between the two branches of the deep flow could therefore be relevant to the distribution of Pacific abyssal mixing. To gain insight into the factors that control the partitioning between these two branches, we develop an abyssal and equator-proximal extension of the "island rule." Novel features include provisions for the presence of hydraulic jumps as well as identification of an appropriate integration circuit for an abyssal layer to the east of the island. Evaluation of the corresponding circulation integral leads to a prediction of 0.4-2.4 Sv of bypass flow. The circulation integral clearly identifies dissipation and frictional drag effects within the Samoan Passage as crucial elements in partitioning the flow.
Formatted Citation: Torres, H. S. and Coauthors, 2019: Diagnosing Ocean-Wave-Turbulence Interactions From Space. Geophys. Res. Lett., 46(15), 8933-8942, doi:10.1029/2019GL083675
Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris (2019). Acceleration and Overturning of the Antarctic Slope Current by Winds, Eddies, and Tides, Journal of Physical Oceanography, 8 (49), 2043-2074, 10.1175/JPO-D-18-0221.1.
Title: Acceleration and Overturning of the Antarctic Slope Current by Winds, Eddies, and Tides
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris
Year: 2019
Formatted Citation: Stewart, A. L., A. Klocker, and D. Menemenlis, 2019: Acceleration and Overturning of the Antarctic Slope Current by Winds, Eddies, and Tides. Journal of Physical Oceanography, 49(8), 2043-2074, doi:10.1175/JPO-D-18-0221.1
Abstract: All exchanges between the open ocean and the Antarctic continental shelf must cross the Antarctic Slope Current (ASC). Previous studies indicate that these exchanges are strongly influenced by mesoscale and tidal variability, yet the mechanisms responsible for setting the ASC's transport and structure have received relatively little attention. In this study the roles of winds, eddies, and tides in accelerating the ASC are investigated using a global ocean-sea ice simulation with very high resolution (1/48° grid spacing). It is found that the circulation along the continental slope is accelerated both by surface stresses, ultimately sourced from the easterly winds, and by mesoscale eddy vorticity fluxes. At the continental shelf break, the ASC exhibits a narrow (~30-50 km), swift (>0.2 m s −1 ) jet, consistent with in situ observations. In this jet the surface stress is substantially reduced, and may even vanish or be directed eastward, because the ocean surface speed matches or exceeds that of the sea ice. The shelfbreak jet is shown to be accelerated by tidal momentum advection, consistent with the phenomenon of tidal rectification. Consequently, the shoreward Ekman transport vanishes and thus the mean overturning circulation that steepens the Antarctic Slope Front (ASF) is primarily due to tidal acceleration. These findings imply that the circulation and mean overturning of the ASC are not only determined by near-Antarctic winds, but also depend crucially on sea ice cover, regionally-dependent mesoscale eddy activity over the continental slope, and the amplitude of tidal flows across the continental shelf break.
Cao, Haijin; Jing, Zhiyou; Fox-Kemper, Baylor; Yan, Tong; Qi, Yiquan (2019). Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea, Journal of Geophysical Research: Oceans, 12 (124), 9364-9383, 10.1029/2019JC015575.
Formatted Citation: Cao, H., Z. Jing, B. Fox-Kemper, T. Yan, and Y. Qi, 2019: Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea. J. Geophys. Res. Ocean., 124(12), 9364-9383, doi:10.1029/2019JC015575
Flexas, M. Mar; Thompson, Andrew F.; Torres, Hector S.; Klein, Patrice; Farrar, J. Thomas; Zhang, Hong; Menemenlis, Dimitris (2019). Global Estimates of the Energy Transfer From the Wind to the Ocean, With Emphasis on Near-Inertial Oscillations, Journal of Geophysical Research: Oceans, 8 (124), 5723-5746, 10.1029/2018JC014453.
Title: Global Estimates of the Energy Transfer From the Wind to the Ocean, With Emphasis on Near-Inertial Oscillations
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Flexas, M. Mar; Thompson, Andrew F.; Torres, Hector S.; Klein, Patrice; Farrar, J. Thomas; Zhang, Hong; Menemenlis, Dimitris
Year: 2019
Formatted Citation: Flexas, M. M., A. F. Thompson, H. S. Torres, P. Klein, J. T. Farrar, H. Zhang, and D. Menemenlis, 2019: Global Estimates of the Energy Transfer From the Wind to the Ocean, With Emphasis on Near-Inertial Oscillations. J. Geophys. Res. Ocean., 124(8), 5723-5746, doi:10.1029/2018JC014453
Springer, Anne; Karegar, Makan A.; Kusche, Jürgen; Keune, Jessica; Kurtz, Wolfgang; Kollet, Stefan (2019). Evidence of daily hydrological loading in GPS time series over Europe, Journal of Geodesy, 10 (93), 2145-2153, 10.1007/s00190-019-01295-1.
Formatted Citation: Springer, A., M. A. Karegar, J. Kusche, J. Keune, W. Kurtz, and S. Kollet, 2019: Evidence of daily hydrological loading in GPS time series over Europe. Journal of Geodesy, 93(10), 2145-2153, doi:10.1007/s00190-019-01295-1
Guo, Haihong; Chen, Zhaohui; Yang, Haiyuan (2019). Poleward Shift of the Pacific North Equatorial Current Bifurcation, Journal of Geophysical Research: Oceans, 7 (124), 4557-4571, 10.1029/2019JC015019.
Formatted Citation: Guo, H., Z. Chen, and H. Yang, 2019: Poleward Shift of the Pacific North Equatorial Current Bifurcation. J. Geophys. Res. Ocean., 124(7), 4557-4571, doi:10.1029/2019JC015019
Lebehot, Alice D.; Halloran, Paul R.; Watson, Andrew J.; McNeall, Doug; Ford, David A.; Landschützer, Peter; Lauvset, Siv K.; Schuster, Ute (2019). Reconciling Observation and Model Trends in North Atlantic Surface CO 2, Global Biogeochemical Cycles, 10 (33), 1204-1222, 10.1029/2019GB006186.
Title: Reconciling Observation and Model Trends in North Atlantic Surface CO 2
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): Lebehot, Alice D.; Halloran, Paul R.; Watson, Andrew J.; McNeall, Doug; Ford, David A.; Landschützer, Peter; Lauvset, Siv K.; Schuster, Ute
Year: 2019
Formatted Citation: Lebehot, A. D., P. R. Halloran, A. J. Watson, D. McNeall, D. A. Ford, P. Landschützer, S. K. Lauvset, and U. Schuster, 2019: Reconciling Observation and Model Trends in North Atlantic Surface CO 2. Global Biogeochemical Cycles, 33(10), 1204-1222, doi:10.1029/2019GB006186
Formatted Citation: Liang, X., M. Losch, L. Nerger, L. Mu, Q. Yang, and C. Liu, 2019: Using Sea Surface Temperature Observations to Constrain Upper Ocean Properties in an Arctic Sea Ice-Ocean Data Assimilation System. J. Geophys. Res. Ocean., 124(7), 4727-4743, doi:10.1029/2019JC015073
Tang, Yi; Stewart, Gillian (2019). The 210Po/210Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects, Marine Chemistry (217), 103692, 10.1016/j.marchem.2019.103692.
Title: The 210Po/210Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects
Type: Journal Article
Publication: Marine Chemistry
Author(s): Tang, Yi; Stewart, Gillian
Year: 2019
Formatted Citation: Tang, Y., and G. Stewart, 2019: The 210Po/210Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects. Marine Chemistry, 217, 103692, doi:10.1016/j.marchem.2019.103692
Formatted Citation: Mu, L., X. Liang, Q. Yang, J. Liu, and F. Zheng, 2019: Arctic Ice Ocean Prediction System: evaluating sea-ice forecasts during Xuelong 's first trans-Arctic Passage in summer 2017. Journal of Glaciology, 65(253), 813-821, doi:10.1017/jog.2019.55
Abstract: In an effort to improve the reliability of Arctic sea-ice predictions, an ensemble-based Arctic Ice Ocean Prediction System (ArcIOPS) has been developed to meet operational demands. The system is based on a regional Arctic configuration of the Massachusetts Institute of Technology general circulation model. A localized error subspace transform ensemble Kalman filter is used to assimilate the weekly merged CryoSat-2 and Soil Moisture and Ocean Salinity sea-ice thickness data together with the daily Advanced Microwave Scanning Radiometer 2 (AMSR2) sea-ice concentration data. The weather forecasts from the Global Forecast System of the National Centers for Environmental Prediction drive the sea ice-ocean coupled model. The ensemble mean sea-ice forecasts were used to facilitate the Chinese National Arctic Research Expedition in summer 2017. The forecasted sea-ice concentration is evaluated against AMSR2 and Special Sensor Microwave Imager/Sounder sea-ice concentration data. The forecasted sea-ice thickness is compared to the in-situ observations and the Pan-Arctic Ice-Ocean Modeling and Assimilation System. These comparisons show the promising potential of ArcIOPS for operational Arctic sea-ice forecasts. Nevertheless, the forecast bias in the Beaufort Sea calls for a delicate parameter calibration and a better design of the assimilation system.
Kuhn, A. M.; Dutkiewicz, S.; Jahn, O.; Clayton, S.; Rynearson, T. A.; Mazloff, M. R.; Barton, A. D. (2019). Temporal and Spatial Scales of Correlation in Marine Phytoplankton Communities, Journal of Geophysical Research: Oceans, 12 (124), 9417-9438, 10.1029/2019JC015331.
Title: Temporal and Spatial Scales of Correlation in Marine Phytoplankton Communities
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Kuhn, A. M.; Dutkiewicz, S.; Jahn, O.; Clayton, S.; Rynearson, T. A.; Mazloff, M. R.; Barton, A. D.
Year: 2019
Formatted Citation: Kuhn, A. M., S. Dutkiewicz, O. Jahn, S. Clayton, T. A. Rynearson, M. R. Mazloff, and A. D. Barton, 2019: Temporal and Spatial Scales of Correlation in Marine Phytoplankton Communities. J. Geophys. Res. Ocean., 124(12), 9417-9438, doi:10.1029/2019JC015331
Formatted Citation: Wang, Z., J. Turner, Y. Wu, and C. Liu, 2019: Rapid Decline of Total Antarctic Sea Ice Extent during 2014-16 Controlled by Wind-Driven Sea Ice Drift. J. Clim., 32(17), 5381-5395, doi:10.1175/JCLI-D-18-0635.1
Abstract: Between 2014 and 2016 the annual mean total extent of Antarctic sea ice decreased by a record, unprecedented amount of 1.6 × 10 6 km 2 , the largest in a record starting in the late 1970s. The mechanisms behind such a rapid decrease remain unknown. Using the outputs of a high-resolution, global ocean-sea ice model we show that the change was predominantly a result of record atmospheric low pressure systems over sectors of the Southern Ocean in 2016, with the associated winds inducing strong sea ice drift. Regions of large positive and negative sea ice extent anomaly were generated by both thermal and dynamic effects of the wind anomalies. Although the strong wind forcing also generated the warmest ocean surface state from April to December 2016, we show that enhanced northward sea ice drift and hence increased melting at lower latitudes driven by strong winds made the dominant contribution to the large decrease in total Antarctic sea ice extent between 2014 and 2016.
Volkov, Denis L.; Lee, Sang-Ki; Domingues, Ricardo; Zhang, Hong; Goes, Marlos (2019). Interannual Sea Level Variability Along the Southeastern Seaboard of the United States in Relation to the Gyre-Scale Heat Divergence in the North Atlantic, Geophysical Research Letters, 13 (46), 7481-7490, 10.1029/2019GL083596.
Title: Interannual Sea Level Variability Along the Southeastern Seaboard of the United States in Relation to the Gyre-Scale Heat Divergence in the North Atlantic
Formatted Citation: Volkov, D. L., S. Lee, R. Domingues, H. Zhang, and M. Goes, 2019: Interannual Sea Level Variability Along the Southeastern Seaboard of the United States in Relation to the Gyre-Scale Heat Divergence in the North Atlantic. Geophys. Res. Lett., 46(13), 7481-7490, doi:10.1029/2019GL083596
Formatted Citation: Qiu, B., S. Chen, B. Powell, P. Colin, D. Rudnick, and M. Schönau, 2019: Nonlinear Short-Term Upper Ocean Circulation Variability in the Tropical Western Pacific. Oceanography, 32(4), 22-31, doi:10.5670/oceanog.2019.408
Yang, Haiyuan; Chang, Ping; Qiu, Bo; Zhang, Qiuying; Wu, Lixin; Chen, Zhaohui; Wang, Hong (2019). Mesoscale Air-Sea Interaction and Its Role in Eddy Energy Dissipation in the Kuroshio Extension, Journal of Climate, 24 (32), 8659-8676, 10.1175/JCLI-D-19-0155.1.
Formatted Citation: Yang, H., P. Chang, B. Qiu, Q. Zhang, L. Wu, Z. Chen, and H. Wang, 2019: Mesoscale Air-Sea Interaction and Its Role in Eddy Energy Dissipation in the Kuroshio Extension. J. Clim., 32(24), 8659-8676, doi:10.1175/JCLI-D-19-0155.1
Abstract: Using the high-resolution Community Earth System Model (CESM) output, this study investigates air-sea interaction and its role in eddy energy dissipation in the Kuroshio Extension (KE) region. Based on an eddy energetics analysis, it is found that the baroclinic pathway associated with temperature variability is the main eddy energy source in this region. Both the air-sea heat flux and wind stress act as eddy killers that remove energy from oceanic eddies. Heat exchange between atmosphere and oceanic eddies dominates the dissipation of eddy temperature variance within the surface layer and accounts for 36% of the total dissipation in the upper 350-m layer. Compared to the heat exchange, the role of wind power in damping the eddy kinetic energy (EKE) is relatively small. Only 18% of EKE dissipation in the upper 350 m is attributed to eddy wind power. Misrepresentation of the damping role of mesoscale ocean-atmosphere interaction can result in an incorrect vertical structure of eddy energy dissipation, leading to an erroneous representation of vertical mixing in the interior ocean.
Formatted Citation: Ibarbalz, F. M. and Coauthors, 2019: Global Trends in Marine Plankton Diversity across Kingdoms of Life. Cell, 179(5), 1084-1097.e21, doi:10.1016/j.cell.2019.10.008
Fu, Yao; Wang, Chunzai; Brandt, Peter; Greatbatch, Richard J. (2019). Interannual Variability of Antarctic Intermediate Water in the Tropical North Atlantic, Journal of Geophysical Research: Oceans, 6 (124), 4044-4057, 10.1029/2018JC014878.
Title: Interannual Variability of Antarctic Intermediate Water in the Tropical North Atlantic
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Fu, Yao; Wang, Chunzai; Brandt, Peter; Greatbatch, Richard J.
Year: 2019
Formatted Citation: Fu, Y., C. Wang, P. Brandt, and R. J. Greatbatch, 2019: Interannual Variability of Antarctic Intermediate Water in the Tropical North Atlantic. J. Geophys. Res. Ocean., 124(6), 4044-4057, doi:10.1029/2018JC014878
Sonnewald, Maike; Wunsch, Carl; Heimbach, Patrick (2019). Unsupervised Learning Reveals Geography of Global Ocean Dynamical Regions, Earth and Space Science, 5 (6), 784-794, 10.1029/2018EA000519.
Title: Unsupervised Learning Reveals Geography of Global Ocean Dynamical Regions
Type: Journal Article
Publication: Earth and Space Science
Author(s): Sonnewald, Maike; Wunsch, Carl; Heimbach, Patrick
Year: 2019
Formatted Citation: Sonnewald, M., C. Wunsch, and P. Heimbach, 2019: Unsupervised Learning Reveals Geography of Global Ocean Dynamical Regions. Earth and Space Science, 6(5), 784-794, doi:10.1029/2018EA000519
Abstract: Dynamically similar regions of the global ocean are identified using a barotropic vorticity (BV) framework from a 20-year mean of the Estimating the Circulation and Climate of the Ocean state estimate at 1° resolution. An unsupervised machine learning algorithm, K-means, objectively clusters the standardized BV equation, identifying five unambiguous regimes. Cluster 1 covers 43 ± 3.3% of the ocean area. Surface and bottom stress torque are balanced by the bottom pressure torque and the nonlinear torque. Cluster 2 covers 24.8 ± 1.2%, where the beta effect balances the bottom pressure torque. Cluster 3 covers 14.6 ± 1.0%, characterized by a "Quasi-Sverdrupian" regime where the beta effect is balanced by the wind and bottom stress term. The small region of Cluster 4 has baroclinic dynamics covering 6.9 ± 2.9% of the ocean. Cluster 5 occurs primarily in the Southern Ocean. Residual "dominantly nonlinear" regions highlight where the BV approach is inadequate, found in areas of rough topography in the Southern Ocean and along western boundaries.
Keywords: big data, global patterns, machine learning, ocean dynamics, ocean modeling, physical oceanography
ECCO Products Used: ECCO-V4
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Khazendar, Ala; Fenty, Ian G.; Carroll, Dustin; Gardner, Alex; Lee, Craig M.; Fukumori, Ichiro; Wang, Ou; Zhang, Hong; Seroussi, Hélène; Moller, Delwyn; Noël, Brice P.Y.; van den Broeke, Michiel R.; Dinardo, Steven; Willis, Josh (2019). Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools, Nature Geoscience, 4 (12), 277-283, 10.1038/s41561-019-0329-3.
Title: Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools
Type: Journal Article
Publication: Nature Geoscience
Author(s): Khazendar, Ala; Fenty, Ian G.; Carroll, Dustin; Gardner, Alex; Lee, Craig M.; Fukumori, Ichiro; Wang, Ou; Zhang, Hong; Seroussi, Hélène; Moller, Delwyn; Noël, Brice P.Y.; van den Broeke, Michiel R.; Dinardo, Steven; Willis, Josh
Year: 2019
Formatted Citation: Khazendar, A. and Coauthors, 2019: Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools. Nature Geoscience, 12(4), 277-283, doi:10.1038/s41561-019-0329-3
Abstract: Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay's upper 250 m have cooled to levels not seen since the mid 1980s. Observations and modelling trace the origins of this cooling to anomalous wintertime heat loss in the boundary current that circulates around the southern half of Greenland. Longer time series of ocean temperature, subglacial discharge and glacier variability strongly suggest that ocean-induced melting at the front has continued to influence glacier dynamics after the disintegration of its floating tongue in 2003. We conclude that projections of Jakobshavn's future contribution to sea-level rise that are based on glacier geometry are insufficient, and that accounting for external forcing is indispensable.
Keywords:
ECCO Products Used: ECCO-V4;LLC270
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Vigo, María; García-García, David; Sempere, María; Chao, Ben (2018). 3D Geostrophy and Volume Transport in the Southern Ocean, Remote Sensing, 5 (10), 715, 10.3390/rs10050715.
Title: 3D Geostrophy and Volume Transport in the Southern Ocean
Type: Journal Article
Publication: Remote Sensing
Author(s): Vigo, María; García-García, David; Sempere, María; Chao, Ben
Year: 2018
Formatted Citation: Vigo, M., D. García-García, M. Sempere, and B. Chao, 2018: 3D Geostrophy and Volume Transport in the Southern Ocean. Remote Sensing, 10(5), 715, doi:10.3390/rs10050715
Lambert, Erwin; Eldevik, Tor; Spall, Michael A. (2018). On the Dynamics and Water Mass Transformation of a Boundary Current Connecting Alpha and Beta Oceans, Journal of Physical Oceanography, 10 (48), 2457-2475, 10.1175/JPO-D-17-0186.1.
Title: On the Dynamics and Water Mass Transformation of a Boundary Current Connecting Alpha and Beta Oceans
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Lambert, Erwin; Eldevik, Tor; Spall, Michael A.
Year: 2018
Formatted Citation: Lambert, E., T. Eldevik, and M. A. Spall, 2018: On the Dynamics and Water Mass Transformation of a Boundary Current Connecting Alpha and Beta Oceans. Journal of Physical Oceanography, 48(10), 2457-2475, doi:10.1175/JPO-D-17-0186.1
Abstract: A subpolar marginal sea, like the Nordic seas, is a transition zone between the temperature-stratified subtropics (the alpha ocean) and the salinity-stratified polar regions (the beta ocean). An inflow of Atlantic Water circulates these seas as a boundary current that is cooled and freshened downstream, eventually to outflow as Deep and Polar Water. Stratification in the boundary region is dominated by a thermocline over the continental slope and a halocline over the continental shelves, separating Atlantic Water from Deep and Polar Water, respectively. A conceptual model is introduced for the circulation and water mass transformation in a subpolar marginal sea to explore the potential interaction between the alpha and beta oceans. Freshwater input into the shelf regions has a slight strengthening effect on the Atlantic inflow, but more prominently impacts the water mass composition of the outflow. This impact of freshwater, characterized by enhancing Polar Water outflow and suppressing Deep Water outflow, is strongly determined by the source location of freshwater. Concretely, perturbations in upstream freshwater sources, like the Baltic freshwater outflow into the Nordic seas, have an order of magnitude larger potential to impact water mass transports than perturbations in downstream sources like the Arctic freshwater outflow. These boundary current dynamics are directly related to the qualitative stratification in transition zones and illustrate the interaction between the alpha and beta oceans.
Foss, Greg; Nguyen, An; Ocaña, Victor; Heimbach, Patrick (2018). Arctic Ocean-Sea Ice Interactions, Proceedings of the Practice and Experience on Advanced Research Computing - PEARC '18, 1-2, 10.1145/3219104.3229429.
Publication: Proceedings of the Practice and Experience on Advanced Research Computing - PEARC '18
Author(s): Foss, Greg; Nguyen, An; Ocaña, Victor; Heimbach, Patrick
Year: 2018
Formatted Citation: Foss, G., A. Nguyen, V. Ocaña, and P. Heimbach, 2018: Arctic Ocean-Sea Ice Interactions. Proceedings of the Practice and Experience on Advanced Research Computing - PEARC '18 ACM Press, New York, New York, USA, 1-2 pp. doi:10.1145/3219104.3229429.
Title: Ocean-Forced Ice-Shelf Thinning in a Synchronously Coupled Ice-Ocean Model
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Jordan, James R; Holland, Paul R; Goldberg, Dan; Snow, Kate; Arthern, Robert; Campin, Jean-Michel; Heimbach, Patrick; Jenkins, Adrian
Year: 2018
Formatted Citation: Jordan, J. R., P. R. Holland, D. Goldberg, K. Snow, R. Arthern, J. Campin, P. Heimbach, and A. Jenkins, 2018: Ocean-Forced Ice-Shelf Thinning in a Synchronously Coupled Ice-Ocean Model. J. Geophys. Res. Ocean., 125(9), 2219-2293, doi:10.1002/2017JC013251
Abstract: The first fully synchronous, coupled ice shelf-ocean model with a fixed grounding line and imposed upstream ice velocity has been developed using the MITgcm (Massachusetts Institute of Technol- ogy general circulation model). Unlike previous, asynchronous, approaches to coupled modeling our approach is fully conservative of heat, salt, and mass. Synchronous coupling is achieved by continuously updating the ice-shelf thickness on the ocean time step. By simulating an idealized, warm-water ice shelf we show how raising the pycnocline leads to a reduction in both ice-shelf mass and back stress, and hence buttressing. Coupled runs show the formation of a western boundary channel in the ice-shelf base due to increased melting on the western boundary due to Coriolis enhanced flow. Eastern boundary ice thickening is also observed. This is not the case when using a simple depth-dependent parameterized melt, as the ice shelf has relatively thinner sides and a thicker central ''bulge'' for a given ice-shelf mass. Ice-shelf geometry arising from the parameterized melt rate tends to underestimate backstress (and therefore buttressing) for a given ice-shelf mass due to a thinner ice shelf at the boundaries when compared to coupled model simulations.
Publication: Journal of Geophysical Research: Oceans
Author(s): Carton, James A.; Chepurin, Gennady A.; Chen, Ligan; Grodsky, Semyon A.
Year: 2018
Formatted Citation: Carton, J. A., G. A. Chepurin, L. Chen, and S. A. Grodsky, 2018: Improved Global Net Surface Heat Flux. J. Geophys. Res. Ocean., 123(5), 3144-3163, doi:10.1002/2017JC013137
Title: Ocean-Induced Melt Triggers Glacier Retreat in Northwest Greenland
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Wood, M; Rignot, E; Fenty, Ian; Menemenlis, Dimitris; Millan, R; Morlighem, M; Mouginot, J; Seroussi, Hélène
Year: 2018
Formatted Citation: Wood, M., E. Rignot, I. Fenty, D. Menemenlis, R. Millan, M. Morlighem, J. Mouginot, and H. Seroussi, 2018: Ocean-Induced Melt Triggers Glacier Retreat in Northwest Greenland. Geophys. Res. Lett., doi:10.1029/2018GL078024
Abstract: In recent decades, tidewater glaciers in Northwest Greenland contributed significantly to sea level rise but exhibited a complex spatial pattern of retreat. Here, we use novel observations of bathymetry and water temperature from NASA's Ocean Melting Greenland mission to quantify the role of warm, salty Atlantic Water in controlling the evolution of 37 glaciers. Modeled ocean-induced undercutting of calving margins compared with ice advection and ice-front retreat observed by satellites from 1985 to 2015 indicate that 35 glaciers retreated when cumulative anomalies in ocean-induced undercutting rose above the range of seasonal variability of calving-front positions, while 2 glaciers standing on shallow sills and colder water did not retreat. Deviations in the observed timing of retreat are explained by residual uncertainties in bathymetry, inefficient mixing of waters in shallow fjords, and the presence of small floating sections. Overall, warmer ocean temperature triggered the retreat, but calving processes dominate ablation (71%).
Tesdal, Jan-Erik; Abernathey, Ryan P.; Goes, Joaquim I.; Gordon, Arnold L.; Haine, Thomas W. N. (2018). Salinity Trends within the Upper Layers of the Subpolar North Atlantic, Journal of Climate, 7 (31), 2675-2698, 10.1175/JCLI-D-17-0532.1.
Title: Salinity Trends within the Upper Layers of the Subpolar North Atlantic
Type: Journal Article
Publication: Journal of Climate
Author(s): Tesdal, Jan-Erik; Abernathey, Ryan P.; Goes, Joaquim I.; Gordon, Arnold L.; Haine, Thomas W. N.
Year: 2018
Formatted Citation: Tesdal, J., R. P. Abernathey, J. I. Goes, A. L. Gordon, and T. W. N. Haine, 2018: Salinity Trends within the Upper Layers of the Subpolar North Atlantic. J. Clim., 31(7), 2675-2698, doi:10.1175/JCLI-D-17-0532.1
Abstract: Examination of a range of salinity products collectively suggests widespread freshening of the North Atlantic from the mid-2000s to the present. Monthly salinity fields reveal negative trends that differ in magnitude and significance between western and eastern regions of the North Atlantic. These differences can be attributed to the large negative interannual excursions in salinity in the western subpolar gyre and the Labrador Sea, which are not apparent in the central or eastern subpolar gyre. This study demonstrates that temporal trends in salinity in the northwest (including the Labrador Sea) are subject to mechanisms that are distinct from those responsible for the salinity trends in the central and eastern North Atlantic. In the western subpolar gyre a negative correlation between near-surface salinity and the circulation strength of the subpolar gyre suggests that negative salinity anomalies are connected to an intensification of the subpolar gyre, which is causing increased flux of freshwater from the East Greenland Current and subsequent transport into the Labrador Sea during the melting season. Analyses of sea surface wind fields suggest that the strength of the subpolar gyre is linked to the North Atlantic Oscillation- and Arctic Oscillation-driven changes in wind stress curl in the eastern subpolar gyre. If this trend of decreasing salinity continues, it has the potential to enhance water column stratification, reduce vertical fluxes of nutrients, and cause a decline in biological production and carbon export in the North Atlantic Ocean.
Zhang, Ying; Feng, Ming; Du, Yan; Phillips, Helen E; Bindoff, Nathaniel L; McPhaden, Michael J (2018). Strengthened Indonesian Throughflow Drives Decadal Warming in the Southern Indian Ocean, Geophysical Research Letters, 12 (45), 6167-6175, 10.1029/2018GL078265.
Title: Strengthened Indonesian Throughflow Drives Decadal Warming in the Southern Indian Ocean
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Zhang, Ying; Feng, Ming; Du, Yan; Phillips, Helen E; Bindoff, Nathaniel L; McPhaden, Michael J
Year: 2018
Formatted Citation: Zhang, Y., M. Feng, Y. Du, H. E. Phillips, N. L. Bindoff, and M. J. McPhaden, 2018: Strengthened Indonesian Throughflow Drives Decadal Warming in the Southern Indian Ocean. Geophys. Res. Lett., 45(12), 6167-6175, doi:10.1029/2018GL078265
Abstract: Remarkable warming of the Southern Indian Ocean during the recent two decades is assessed using a heat budget analysis based on the Estimating the Circulation and Climate of the Ocean version 4 release 3 model results. The annual mean temperature averaged in the upper-700 m Southern Indian Ocean during 1998-2015 has experienced significant warming at a rate of 1.03 × 10−2 °C/year. A heat budget analysis indicates that the increase is mostly driven by decreased cooling from net air-sea heat flux and increased warming from heat advection. Increased Indonesian Throughflow advection is the largest contributor to warming the upper 700 m of the Southern Indian Ocean, while the reduction of surface turbulent heat flux is of secondary importance. These results expand our understanding of the decadal heat balance in the Indian Ocean and of Indo-Pacific decadal climate variability.
Ponte, Rui M; Quinn, Katherine J; Piecuch, Christopher G (2018). Accounting for Gravitational Attraction and Loading Effects from Land Ice on Absolute Sea Level, Journal of Atmospheric and Oceanic Technology, 2 (35), 405-410, 10.1175/JTECH-D-17-0092.1.
Title: Accounting for Gravitational Attraction and Loading Effects from Land Ice on Absolute Sea Level
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Ponte, Rui M; Quinn, Katherine J; Piecuch, Christopher G
Year: 2018
Formatted Citation: Ponte, R. M., K. J. Quinn, and C. G. Piecuch, 2018: Accounting for Gravitational Attraction and Loading Effects from Land Ice on Absolute Sea Level. Journal of Atmospheric and Oceanic Technology, 35(2), 405-410, doi:10.1175/JTECH-D-17-0092.1
Abstract: Gravitational attraction and loading (GAL) effects associated with ongoing long-term changes in land ice are expected to cause spatially varying trends in absolute sea level ζ, as measured by satellite altimeters. The largest spatial gradients in ζ trends, predicted from solving the sea level equation using GRACE retrievals of mass distribution over land for the period 2005-15, occur near Greenland and West Antarctica, consistent with a strong local land ice loss. Misinterpreting the estimated static GAL trends in ζ as dynamic pressure gradients can lead to substantial errors in large-scale geostrophic transports across the Southern Ocean and the subpolar North Atlantic over the analyzed decade. South of Greenland, where altimeter sea level and hydrography (Argo) data coverage is good, the residual ζ minus steric height trends are similar in magnitude and sign to the gravitationally based predictions. In addition, estimated GAL-related trends are as large-if not larger than-other factors, such as deep steric height, dynamic bottom pressure, and glacial isostatic rebound. Thus, accounting for static GAL effects on ζ records, which are commonly neglected in oceanographic studies, seems important for a quantitative interpretation of the observed ζ trends.
Ponte, R M; Piecuch, C G (2018). Mechanisms Controlling Global Mean Sea Surface Temperature Determined From a State Estimate, Geophysical Research Letters, 7 (45), 3221-3227, 10.1002/2017GL076821.
Title: Mechanisms Controlling Global Mean Sea Surface Temperature Determined From a State Estimate
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Ponte, R M; Piecuch, C G
Year: 2018
Formatted Citation: Ponte, R. M., and C. G. Piecuch, 2018: Mechanisms Controlling Global Mean Sea Surface Temperature Determined From a State Estimate. Geophys. Res. Lett., 45(7), 3221-3227, doi:10.1002/2017GL076821
Abstract: Global mean sea surface temperature ( ) is a variable of primary interest in studies of climate variability and change. The temporal evolution of can be influenced by surface heat fluxes ( ) and by diffusion ( ) and advection ( ) processes internal to the ocean, but quantifying the contribution of these different factors from data alone is prone to substantial uncertainties. Here we derive a closed budget for the period 1993-2015 based on a global ocean state estimate, which is an exact solution of a general circulation model constrained to most extant ocean observations through advanced optimization methods. The estimated average temperature of the top (10-m thick) level in the model, taken to represent , shows relatively small variability at most time scales compared to , , or , reflecting the tendency for largely balancing effects from all the latter terms. The seasonal cycle in is mostly determined by small imbalances between and , with negligible contributions from . While seems to simply damp at the annual period, a different dynamical role for at semiannual period is suggested by it being larger than . At periods longer than annual, contributes importantly to variability, pointing to the direct influence of the variable ocean circulation on and mean surface climate.
Belonenko, T. V.; Volkov, D. L.; Koldunov, A. V. (2018). Shelf Waves in the Beaufort Sea in a High-Resolution Ocean Model, Oceanology, 6 (58), 778-785, 10.1134/S0001437018060024.
Title: Shelf Waves in the Beaufort Sea in a High-Resolution Ocean Model
Type: Journal Article
Publication: Oceanology
Author(s): Belonenko, T. V.; Volkov, D. L.; Koldunov, A. V.
Year: 2018
Formatted Citation: Belonenko, T. V., D. L. Volkov, and A. V. Koldunov, 2018: Shelf Waves in the Beaufort Sea in a High-Resolution Ocean Model. Oceanology, 58(6), 778-785, doi:10.1134/S0001437018060024
Fukumori, Ichiro; Heimbach, Patrick; Ponte, Rui M; Wunsch, Carl (2018). A Dynamically Consistent, Multivariable Ocean Climatology, Bulletin of the American Meteorological Society, 10 (99), 2107-2128, 10.1175/BAMS-D-17-0213.1.
Title: A Dynamically Consistent, Multivariable Ocean Climatology
Type: Journal Article
Publication: Bulletin of the American Meteorological Society
Author(s): Fukumori, Ichiro; Heimbach, Patrick; Ponte, Rui M; Wunsch, Carl
Year: 2018
Formatted Citation: Fukumori, I., P. Heimbach, R. M. Ponte, and C. Wunsch, 2018: A Dynamically Consistent, Multivariable Ocean Climatology. Bull. Am. Meteorol. Soc., 99(10), 2107-2128, doi:10.1175/BAMS-D-17-0213.1
Abstract: A dynamically consistent 20-yr average ocean climatology based on monthly values during the years 1994-2013 has been produced from the most recent state estimate of the Estimating the Circulation and Climate of the Ocean (ECCO) project, globally, top to bottom. The estimate was produced from a least squares fit of a free-running ocean general circulation model to almost all available near-global data. Data coverage in space and time during this period is far more homogeneous than in any earlier interval and includes CTD, elephant seal, and Argo temperature and salinity profiles; sea ice coverage; full altimetric and gravity-field coverage; satellite sea surface temperatures; and the initializing meteorological coverage from the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim). Dominant remaining data inhomogeneity arises from increasing coverage from the Argo profiles from about 2000 to the present. The state estimate exactly satisfies the primitive equations of the free-running Massachusetts Institute of Technology General Circulation Model (MITgcm) at all times and hence produces values satisfying the fundamental conservation laws of energy, freshwater, and so forth, permitting its use for climate change studies. Quantities such as calculated heat content depend upon all observations, not just temperature, for example, altimetric height and meteorological exchanges. Output files are publicly available in Network Common Data Form (netCDF) and MATLAB form and include hydrographic variables, three components of velocity, and pressure at all depths, as well as other variables, including inferred air?sea momentum and buoyancy fluxes, 3D mixing parameters, and sea ice cover.
Fu, Lee-Lueng; Lee, Tong; Liu, W. Timothy; Kwok, Ronald (2018). 50 Years of Satellite Remote Sensing of the Ocean, Meteorological Monographs (59), 5.1-5.46, 10.1175/AMSMONOGRAPHS-D-18-0010.1.
Title: 50 Years of Satellite Remote Sensing of the Ocean
Type: Journal Article
Publication: Meteorological Monographs
Author(s): Fu, Lee-Lueng; Lee, Tong; Liu, W. Timothy; Kwok, Ronald
Year: 2018
Formatted Citation: Fu, L., T. Lee, W. T. Liu, and R. Kwok, 2018: 50 Years of Satellite Remote Sensing of the Ocean. Meteorological Monographs, 59, 5.1-5.46, doi:10.1175/AMSMONOGRAPHS-D-18-0010.1
Wunsch, Carl (2018). Towards determining uncertainties in global oceanic mean values of heat, salt, and surface elevation, Tellus A: Dynamic Meteorology and Oceanography, 1 (70), 1-14, 10.1080/16000870.2018.1471911.
Title: Towards determining uncertainties in global oceanic mean values of heat, salt, and surface elevation
Type: Journal Article
Publication: Tellus A: Dynamic Meteorology and Oceanography
Author(s): Wunsch, Carl
Year: 2018
Formatted Citation: Wunsch, C., 2018: Towards determining uncertainties in global oceanic mean values of heat, salt, and surface elevation. Tellus A: Dynamic Meteorology and Oceanography, 70(1), 1-14, doi:10.1080/16000870.2018.1471911
Abstract: Lower-bounds on uncertainties in oceanic data and a model are calculated for the 20-year time means and their temporal evolution for oceanic temperature, salinity, and sea surface height, during the data-dense interval 1994-2013. The essential step of separating stochastic from systematic or deterministic elements of the fields is explored by suppressing the globally correlated components of the fields. Justification lies in the physics and the brevity of a 20-year estimate relative to the full oceanic adjustment time, and the inferred near-linearity of response on short time intervals. Lower-bound uncertainties reflecting the only stochastic elements of the state estimate are then calculated from bootstrap estimates. Trends are estimated as 2:2 6 0:2 mm=y in elevation, 0.0011 ± 0.0001 C/y, and ( 2.825 ± 0.17) 10 5 for surface elevation, temperature and salt, with formal 2-standard deviation uncertainties. The temperature change corresponds to a 20-year average ocean heating rate of 0:4860:1 W/m2 of which 0.1 W/m2 arises from the geothermal forcing. Systematic errors must be determined separately.
Wang, Jinbo; Qiu, Bo; Menemenlis, Dimitris; Thomas Farrar, J; Chao, Yi; Thompson, Andrew F; Flexas, Mar M; Fu, Lee Lueng; Qiu, Bo; Menemenlis, Dimitris; Thomas Farrar, J; Chao, Yi; Thompson, Andrew F; Flexas, Mar M (2018). An observing system simulation experiment for the calibration and validation of the Surface Water Ocean Topography Sea surface height measurement using in situ platforms, J. Atmos. Ocean. Technol., 2 (35), 281-297, 10.1175/JTECH-D-17-0076.1.
Title: An observing system simulation experiment for the calibration and validation of the Surface Water Ocean Topography Sea surface height measurement using in situ platforms
Type: Journal Article
Publication: J. Atmos. Ocean. Technol.
Author(s): Wang, Jinbo; Qiu, Bo; Menemenlis, Dimitris; Thomas Farrar, J; Chao, Yi; Thompson, Andrew F; Flexas, Mar M; Fu, Lee Lueng; Qiu, Bo; Menemenlis, Dimitris; Thomas Farrar, J; Chao, Yi; Thompson, Andrew F; Flexas, Mar M
Year: 2018
Formatted Citation: Wang, J. and Coauthors, 2018: An observing system simulation experiment for the calibration and validation of the Surface Water Ocean Topography Sea surface height measurement using in situ platforms. J. Atmos. Ocean. Technol., 35(2), 281-297, doi:10.1175/JTECH-D-17-0076.1
Abstract: The wavenumber spectrum of sea surface height (SSH) is an important indicator of the dynamics of the ocean interior. While the SSH wavenumber spectrum has been well studied at mesoscale wavelengths and longer, using both in situ oceanographic measurements and satellite altimetry, it remains largely unknown for wavelengths less than $~$70 km. The Surface Water Ocean Topography (SWOT) satellite mission aims to resolve the SSH wavenumber spectrum at 15-150-km wavelengths, which is specified as one of the mission requirements. The mission calibration and validation (CalVal) requires the ground truth of a synoptic SSH field to resolve the targeted wavelengths, but no existing observational network is able to fulfill the task. A high-resolution global ocean simulation is used to conduct an observing system simulation experiment (OSSE) to identify the suitable oceanographic in situ measurements for SWOT SSH CalVal. After fixing 20 measuring locations (the minimum number for resolving 15-150-km wavelengths)...
Formatted Citation: Qiu, B., S. Chen, P. Klein, J. Wang, H. S. Torres, L. Fu, and D. Menemenlis, 2018: Seasonality in Transition Scale from Balanced to Unbalanced Motions in the World Ocean. J. Phys. Oceanogr., 48(3), 591-605, doi:10.1175/JPO-D-17-0169.1
Abstract: The transition scale Lt from balanced geostrophic motions to unbalanced wave motions, including near-inertial flows, internal tides, and inertia-gravity wave continuum, is explored using the output from a global 1/48° horizontal resolution Massachusetts Institute of Technology general circulation model (MITgcm) simulation. Defined as the wavelength with equal balanced and unbalanced motion kinetic energy (KE) spectral density, Lt is detected to be geographically highly inhomogeneous: it falls below 40 km in the western boundary current and Antarctic Circumpolar Current regions, increases to 40-100 km in the interior subtropical and subpolar gyres, and exceeds, in general, 200 km in the tropical oceans. With the exception of the Pacific and Indian sectors of the Southern Ocean, the seasonal KE fluctuations of the surface balanced and unbalanced motions are out of phase because of the occurrence of mixed layer instability in winter and trapping of unbalanced motion KE in shallow mixed layer in summe...
Keywords: Altimetry, General circulation models, Inertia-gravity waves, LLC4320, Mesoscale processes, Seasonal variability, Small scale processes
Su, Zhan; Wang, Jinbo; Klein, Patrice; Thompson, Andrew F; Menemenlis, Dimitris (2018). Ocean submesoscales as a key component of the global heat budget, Nat. Commun., 775 (9), 1-8, 10.1038/s41467-018-02983-w.
Title: Ocean submesoscales as a key component of the global heat budget
Type: Journal Article
Publication: Nat. Commun.
Author(s): Su, Zhan; Wang, Jinbo; Klein, Patrice; Thompson, Andrew F; Menemenlis, Dimitris
Year: 2018
Formatted Citation: Su, Z., J. Wang, P. Klein, A. F. Thompson, and D. Menemenlis, 2018: Ocean submesoscales as a key component of the global heat budget. Nat. Commun., 9(775), 1-8, doi:10.1038/s41467-018-02983-w
Abstract: Recent studies highlight that oceanic motions associated with horizontal scales smaller than 50 km, defined here as submesoscales, lead to anomalous vertical heat fluxes from colder to warmer waters. This unique transport property is not captured in climate models that have insufficient resolution to simulate these submesoscale dynamics. Here, we use an ocean model with an unprecedented resolution that, for the first time, globally resolves sub-mesoscale heat transport. Upper-ocean submesoscale turbulence produces a systematically-upward heat transport that is five times larger than mesoscale heat transport, with winter-time averages up to 100 W/m 2 for mid-latitudes. Compared to a lower-resolution model, submesoscale heat transport warms the sea surface up to 0.3 °C and produces an upward annual-mean air-sea heat flux anomaly of 4-10 W/m 2 at mid-latitudes. These results indicate that submesoscale dynamics are critical to the transport of heat between the ocean interior and the atmosphere, and are thus a key component of the Earth's climate.
Formatted Citation: Nakayama, Y., D. Menemenlis, H. Zhang, M. Schodlok, and E. Rignot, 2018: Origin of Circumpolar Deep Water intruding onto the Amundsen and Bellingshausen Sea continental shelves. Nat. Commun., 9(1), 3403, doi:10.1038/s41467-018-05813-1
Abstract: Melting of West Antarctic ice shelves is enhanced by Circumpolar Deep Water (CDW) intruding onto the Amundsen and Bellingshausen Seas (ABS) continental shelves. Despite existing studies of cross-shelf and on-shelf CDW transports, CDW pathways onto the ABS originating from further offshore have never been investigated. Here, we investigate CDW pathways onto the ABS using a regional ocean model. Simulated CDW tracers from a zonal section across 67°S (S04P) circulate along the Antarctic Circumpolar Current (ACC) and Ross Gyre (RG) and travel into ABS continental shelf after 3-5 years, but source locations are shifted westward by $~$900 km along S04P in 2001-2006 compared to 2009-2014. We find that simulated on-and off-shelf CDW is $~$0.1-0.2 °C warmer in the 2009-2014 case than in the 2001-2006 case together with changes in simulated ocean circulation. These differences are primarily caused by lateral, rather than surface, boundary conditions, implying that large-scale atmospheric and ocean circulations are able to control CDW pathways and thus off-and on-shelf CDW properties.
Torres, Hector S; Klein, Patrice; Menemenlis, Dimitris; Qiu, Bo; Su, Zhan; Wang, Jinbo; Chen, Shuiming; Fu, Lee-Lueng (2018). Partitioning ocean motions into balanced motions and internal gravity waves: A modeling study in anticipation of future space missions, J. Geophys. Res. Ocean., 11 (123), 8084-8105, 10.1029/2018JC014438.
Formatted Citation: Torres, H. S., P. Klein, D. Menemenlis, B. Qiu, Z. Su, J. Wang, S. Chen, and L. Fu, 2018: Partitioning ocean motions into balanced motions and internal gravity waves: A modeling study in anticipation of future space missions. J. Geophys. Res. Ocean., 123(11), 8084-8105, doi:10.1029/2018JC014438
Abstract: Internal gravity waves (IGWs) and balanced motions (BMs) with scales <100-km capture most of the vertical velocity field in the upper ocean. They have, however, different impacts on the ocean energy budget, which explains the need to partition motions into BMs and IGWs. One way is to exploit the synergy of using different satellite observations, the only observations with global coverage, and a reasonable spatial and temporal resolution. But we need first to characterize and understand their signatures on the different surface oceanic fields. This study addresses this issue by using an ocean global numerical simulation with high-resolution (1/48°). Our methodology is based on the analysis of the 12,000 frequency-wave number spectra to discriminate these two classes of motions in the surface kinetic energy, sea surface height, sea surface temperature, sea surface salinity, relative vorticity, and divergence fields and for two seasons. Results reveal a complex picture worldwide of the partition of motions between IGWs and BMs in the different surface fields, depending on the season, the hemisphere, and low and high eddy kinetic energy regions. But they also highlight some generic properties on the impact of these two classes of motions on the different fields. This points to the synergy of using present and future satellite observations to assess the ocean kinetic energy on a global scale. The 12,000 frequency-wave number spectra represent a World Ocean Atlas of the surface ocean dynamics not fully exploited in the present study. We hope the use of this World Ocean Atlas by other studies will lead to extend much these results.
Arbic, Brian K; Alford, Matthew H; Ansong, Joseph K; Buijsman, Maarten C; Ciotti, Robert B; Farrar, J Thomas; Hallberg, Robert W; Henze, Christopher E; Hill, Christopher N; Luecke, Conrad A; Menemenlis, Dimitris; Metzger, E Joseph; Müller, Malte; Nelson, Arin D; Nelson, Bron C; Ngodock, Hans E; Ponte, Rui M; Richman, James G; Savage, Anna C; Scott, Robert B; Shriver, Jay F; Simmons, Harper L; Souopgui, Innocent; Timko, Patrick G; Wallcraft, Allan J; Zamudio, Luis; Zhao, Zhongxiang (2018). A Primer on Global Internal Tide and Internal Gravity Wave Continuum Modeling in HYCOM and MITgcm, New Front. Oper. Oceanogr., 307-392, 10.17125/gov2018.ch13.
Title: A Primer on Global Internal Tide and Internal Gravity Wave Continuum Modeling in HYCOM and MITgcm
Type: Book Section
Publication: New Front. Oper. Oceanogr.
Author(s): Arbic, Brian K; Alford, Matthew H; Ansong, Joseph K; Buijsman, Maarten C; Ciotti, Robert B; Farrar, J Thomas; Hallberg, Robert W; Henze, Christopher E; Hill, Christopher N; Luecke, Conrad A; Menemenlis, Dimitris; Metzger, E Joseph; Müller, Malte; Nelson, Arin D; Nelson, Bron C; Ngodock, Hans E; Ponte, Rui M; Richman, James G; Savage, Anna C; Scott, Robert B; Shriver, Jay F; Simmons, Harper L; Souopgui, Innocent; Timko, Patrick G; Wallcraft, Allan J; Zamudio, Luis; Zhao, Zhongxiang
Year: 2018
Formatted Citation: Arbic, B. K. and Coauthors, 2018: A Primer on Global Internal Tide and Internal Gravity Wave Continuum Modeling in HYCOM and MITgcm. New Front. Oper. Oceanogr., E. P. Chassignet, A. Pascual, J. Tintoré, and J. Verron, Eds., 307-392, doi:10.17125/gov2018.ch13
Formatted Citation: Ardhuin, F. and Coauthors, 2018: Measuring currents, ice drift, and waves from space: The Sea surface KInematics Multiscale monitoring (SKIM) concept. Ocean Sci., 14(3), 337-354, doi:10.5194/os-14-337-2018
Abstract: We propose a new satellite mission that uses a near-nadir Ka-band Doppler radar to measure surface currents, ice drift and ocean waves at spatial scales of 40 km and more, with snapshots at least every day for latitudes 75 to 82, and every few days otherwise. The use of incidence angles at 6 and 12 degrees allows a measurement of the directional wave spectrum which yields accurate corrections of the wave-induced bias in the current measurements. The instrument principle, algorithm for current velocity and mission performance are presented here. The proposed instrument can reveal features on tropical ocean and marginal ice zone dynamics that are inaccessible to other measurement systems, as well as a global monitoring of the ocean mesoscale that surpasses the capability of today's nadir altimeters. Measuring ocean wave properties facilitates many applications, from wave-current interactions and air-sea fluxes to the transport and convergence of marine plastic debris and assessment of marine and coastal hazards.
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Goldberg, D N; Snow, K; Holland, P; Jordan, J R; Campin, Jean-Michel; Heimbach, P; Arthern, R; Jenkins, A (2018). Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z -coordinate ocean model, Ocean Modelling (125), 45-60, 10.1016/j.ocemod.2018.03.005.
Title: Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z -coordinate ocean model
Type: Journal Article
Publication: Ocean Modelling
Author(s): Goldberg, D N; Snow, K; Holland, P; Jordan, J R; Campin, Jean-Michel; Heimbach, P; Arthern, R; Jenkins, A
Year: 2018
Formatted Citation: Goldberg, D. N., K. Snow, P. Holland, J. R. Jordan, J. Campin, P. Heimbach, R. Arthern, and A. Jenkins, 2018: Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z -coordinate ocean model. Ocean Modelling, 125, 45-60, doi:10.1016/j.ocemod.2018.03.005
Abstract: Synchronous coupling is developed between an ice sheet model and a z-coordinate ocean model (the MITgcm). A previously-developed scheme to allow continuous vertical movement of the ice-ocean interface of a floating ice shelf ("vertical coupling") is built upon to allow continuous movement of the grounding line, or point of floa- tation of the ice sheet ("horizontal coupling"). Horizontal coupling is implemented through the maintenance of a thin layer of ocean ( ∼ 1 m) under grounded ice, which is inflated into the real ocean as the ice ungrounds. This is accomplished through a modification of the ocean model's nonlinear free surface evolution in a manner akin to a hydrological model in the presence of steep bathymetry. The coupled model is applied to a number of idealized geometries and shown to successfully represent ocean-forced marine ice sheet retreat while maintaining a continuous ocean circulation.
Sonnewald, Maike; Wunsch, Carl; Heimbach, Patrick (2018). Linear Predictability: A Sea Surface Height Case Study, Journal of Climate, 7 (31), 2599-2611, 10.1175/JCLI-D-17-0142.1.
Title: Linear Predictability: A Sea Surface Height Case Study
Type: Journal Article
Publication: Journal of Climate
Author(s): Sonnewald, Maike; Wunsch, Carl; Heimbach, Patrick
Year: 2018
Formatted Citation: Sonnewald, M., C. Wunsch, and P. Heimbach, 2018: Linear Predictability: A Sea Surface Height Case Study. J. Clim., 31(7), 2599-2611, doi:10.1175/JCLI-D-17-0142.1
Abstract: A benchmark of linear predictability of sea surface height (SSH) globally is presented, complementing more complicated studies of SSH predictability. Twenty years of the Estimating the Circulation and Cli- mate of the Ocean (ECCOv4) state estimate (1992-2011) are used, fitting autoregressive moving average [ARMA(n, m)] models where the order of the coefficients is chosen by the Akaike information criteria (AIC). Up to 50% of the ocean SSH variability is dominated by the seasonal signal. The variance accounted for by the nonseasonal SSH is particularly distinct in the Southern and Pacific Oceans, containing .95% of the total SSH variance, and the expected prediction error growth takes a few months to reach a threshold of 1 cm. Isolated regions take 12 months or more to cross an accuracy threshold of 1 cm. Including the trend significantly increases the time taken to reach the threshold, particularly in the South Pacific. Annual averaging has expected pre- diction error growth of a few years to reach a threshold of 1 cm. Including the trend mainly increases the time taken to reach the threshold, but the time series is short and noisy.
Ferreira, David; Cessi, Paola; Coxall, Helen K; de Boer, Agatha; Dijkstra, Henk A; Drijfhout, Sybren S; Eldevik, Tor; Harnik, Nili; McManus, Jerry F; Marshall, David P; Nilsson, Johan; Roquet, Fabien; Schneider, Tapio; Wills, Robert C (2018). Atlantic-Pacific Asymmetry in Deep Water Formation, Annual Review of Earth and Planetary Sciences, 1 (46), 327-352, 10.1146/annurev-earth-082517-010045.
Title: Atlantic-Pacific Asymmetry in Deep Water Formation
Type: Journal Article
Publication: Annual Review of Earth and Planetary Sciences
Author(s): Ferreira, David; Cessi, Paola; Coxall, Helen K; de Boer, Agatha; Dijkstra, Henk A; Drijfhout, Sybren S; Eldevik, Tor; Harnik, Nili; McManus, Jerry F; Marshall, David P; Nilsson, Johan; Roquet, Fabien; Schneider, Tapio; Wills, Robert C
Year: 2018
Formatted Citation: Ferreira, D. and Coauthors, 2018: Atlantic-Pacific Asymmetry in Deep Water Formation. Annual Review of Earth and Planetary Sciences, 46(1), 327-352, doi:10.1146/annurev-earth-082517-010045
Abstract: While the Atlantic Ocean is ventilated by high-latitude deep water formation and exhibits a pole-to-pole overturning circulation, the Pacific Ocean does not. This asymmetric global overturning pattern has persisted for the past 2-3 million years, with evidence for different ventilation modes in the deeper past. In the current climate, the Atlantic-Pacific asymmetry occurs because the Atlantic is more saline, enabling deep convection. To what extent the salinity contrast between the two basins is dominated by atmospheric processes (larger net evaporation over the Atlantic) or oceanic processes (salinity transport into the Atlantic) remains an outstanding question. Numerical simulations have provided support for both mechanisms; observations of the present climate support a strong role for atmospheric processes as well as some modulation by oceanic processes. A major avenue for future work is the quantification of the various processes at play to identify which mechanisms are primary in different climate states.
Khatiwala, Samar; Graven, Heather; Payne, Sarah; Heimbach, Patrick (2018). Changes to the Air-Sea Flux and Distribution of Radiocarbon in the Ocean Over the 21st Century, Geophysical Research Letters, 11 (45), 5617-5626, 10.1029/2018GL078172.
Title: Changes to the Air-Sea Flux and Distribution of Radiocarbon in the Ocean Over the 21st Century
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Khatiwala, Samar; Graven, Heather; Payne, Sarah; Heimbach, Patrick
Year: 2018
Formatted Citation: Khatiwala, S., H. Graven, S. Payne, and P. Heimbach, 2018: Changes to the Air-Sea Flux and Distribution of Radiocarbon in the Ocean Over the 21st Century. Geophys. Res. Lett., 45(11), 5617-5626, doi:10.1029/2018GL078172
Abstract: We investigate the spatiotemporal evolution of radiocarbon (Δ14C) in the ocean over the 21st century under different scenarios for anthropogenic CO2 emissions and atmospheric CO2 and radiocarbon changes using a 3-D ocean carbon cycle model. Strong decreases in atmospheric Δ14C in the high-emission scenario result in strong outgassing of 14C over 2050-2100, causing Δ14C spatial gradients in the surface ocean and vertical gradients between the surface and intermediate waters to reverse sign. Surface Δ14C in the subtropical gyres is lower than Δ14C in Pacific Deep Water and Southern Ocean surface water in 2100. In the low-emission scenario, ocean Δ14C remains slightly higher than in 1950 and relatively constant over 2050-2100. Over the next 20 years we find decadal changes in Δ14C of −30‰ to +5‰ in the upper 2 km of the ocean, which should be detectable with continued hydrographic surveys. Our simulations can help in planning future observations, and they provide a baseline for investigating natural or anthropogenic changes in ocean circulation using ocean Δ14C observations and models.
Hutter, Nils; Losch, Martin; Menemenlis, Dimitris (2018). Scaling Properties of Arctic Sea Ice Deformation in a High-Resolution Viscous-Plastic Sea Ice Model and in Satellite Observations, Journal of Geophysical Research: Oceans, 1 (123), 672-687, 10.1002/2017JC013119.
Formatted Citation: Hutter, N., M. Losch, and D. Menemenlis, 2018: Scaling Properties of Arctic Sea Ice Deformation in a High-Resolution Viscous-Plastic Sea Ice Model and in Satellite Observations. J. Geophys. Res. Ocean., 123(1), 672-687, doi:10.1002/2017JC013119
Abstract: Sea ice models with the traditional viscous-plastic (VP) rheology and very small horizontal grid spacing can resolve leads and deformation rates localized along Linear Kinematic Features (LKF). In a 1 km pan-Arctic sea ice-ocean simulation, the small-scale sea ice deformations are evaluated with a scaling analysis in relation to satellite observations of the Envisat Geophysical Processor System (EGPS) in the Central Arctic. A new coupled scaling analysis for data on Eulerian grids is used to determine the spatial and temporal scaling and the coupling between temporal and spatial scales. The spatial scaling of the modeled sea ice deformation implies multifractality. It is also coupled to temporal scales and varies realistically by region and season. The agreement of the spatial scaling with satellite observations challenges previous results with VP models at coarser resolution, which did not reproduce the observed scaling. The temporal scaling analysis shows that the VP model, as configured in this 1 km simulation, does not fully resolve the intermittency of sea ice deformation that is observed in satellite data.
Jones, Daniel C; Forget, Gael; Sinha, Bablu; Josey, Simon A; Boland, Emma J D; Meijers, Andrew J S; Shuckburgh, Emily (2018). Local and Remote Influences on the Heat Content of the Labrador Sea: An Adjoint Sensitivity Study, Journal of Geophysical Research: Oceans, 4 (123), 2646-2667, 10.1002/2018JC013774.
Title: Local and Remote Influences on the Heat Content of the Labrador Sea: An Adjoint Sensitivity Study
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Jones, Daniel C; Forget, Gael; Sinha, Bablu; Josey, Simon A; Boland, Emma J D; Meijers, Andrew J S; Shuckburgh, Emily
Year: 2018
Formatted Citation: Jones, D. C., G. Forget, B. Sinha, S. A. Josey, E. J. D. Boland, A. J. S. Meijers, and E. Shuckburgh, 2018: Local and Remote Influences on the Heat Content of the Labrador Sea: An Adjoint Sensitivity Study. J. Geophys. Res. Ocean., 123(4), 2646-2667, doi:10.1002/2018JC013774
Abstract: The Labrador Sea is one of the few regions on the planet where the interior ocean can exchange heat directly with the atmosphere via strong, localized, wintertime convection, with possible implications for the state of North Atlantic climate and global surface warming. Using an observationally constrained ocean adjoint model, we find that annual?mean Labrador Sea heat content is sensitive to temperature/salinity changes (1) along potential source water pathways (e.g., the subpolar gyre, the North Atlantic Current, the Gulf Stream) and (2) along the West African and European shelves, which are not significant source water regions for the Labrador Sea. The West African coastal/shelf adjustment mechanism, which may be excited by changes in along?shelf wind stress, involves pressure anomalies that propagate along a coastal waveguide toward Greenland, changing the across?shelf pressure gradient in the North Atlantic and altering heat convergence in the Labrador Sea. We also find that nonlocal (in space and time) heat fluxes (e.g., in the Irminger Sea, the seas south of Iceland) can have a strong impact on Labrador Sea heat content. Understanding and predicting the state of the Labrador Sea and its potential impacts on North Atlantic climate and global surface warming will require monitoring of oceanic and atmospheric properties at remote sites in the Irminger Sea, the subpolar gyre, and along the West African and European shelf/coast system, among others.
Stewart, Andrew L; Klocker, Andreas; Menemenlis, Dimitris (2018). Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation, Geophysical Research Letters, 2 (45), 834-845, 10.1002/2017GL075677.
Title: Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Stewart, Andrew L; Klocker, Andreas; Menemenlis, Dimitris
Year: 2018
Formatted Citation: Stewart, A. L., A. Klocker, and D. Menemenlis, 2018: Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation. Geophys. Res. Lett., 45(2), 834-845, doi:10.1002/2017GL075677
Abstract: Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at eddy- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to eddies and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that eddies transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the eddy heat flux to balance the net shoreward heat transport. The eddy-driven cross-slope overturning circulation is too weak to account for the eddy heat flux. This suggests that isopycnal eddy stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.
Piecuch, Christopher G; Landerer, Felix W; Ponte, Rui M (2018). Tide gauge records reveal improved processing of gravity recovery and climate experiment time-variable mass solutions over the coastal ocean, Geophysical Journal International, 2 (214), 1401-1412, 10.1093/gji/ggy207.
Title: Tide gauge records reveal improved processing of gravity recovery and climate experiment time-variable mass solutions over the coastal ocean
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Piecuch, Christopher G; Landerer, Felix W; Ponte, Rui M
Year: 2018
Formatted Citation: Piecuch, C. G., F. W. Landerer, and R. M. Ponte, 2018: Tide gauge records reveal improved processing of gravity recovery and climate experiment time-variable mass solutions over the coastal ocean. Geophysical Journal International, 214(2), 1401-1412, doi:10.1093/gji/ggy207
Abstract: Monthly ocean bottom pressure solutions from the Gravity Recovery and Climate Experiment (GRACE), derived using surface spherical cap mass concentration (MC) blocks and spherical harmonics (SH) basis functions, are compared to tide gauge (TG) monthly averaged sea level data over 2003-2015 to evaluate improved gravimetric data processing methods near the coast. MC solutions can explain ≳ 42 per cent of the monthly variance in TG time-series over broad shelf regions and in semi-enclosed marginal seas. MC solutions also generally explain ~ 5-32 per cent more TG data variance than SH estimates. Applying a coastline resolution improvement algorithm in the GRACE data processing leads to ~ 31 per cent more variance in TG records explained by the MC solution on average compared to not using this algorithm. Synthetic observations sampled from an ocean general circulation model exhibit similar patterns of correspondence between modelled TG and MC time-series and differences between MC and SH time-series in terms of their relationship with TG time-series, suggesting that observational results here are generally consistent with expectations from ocean dynamics. This work demonstrates the improved quality of recent MC solutions compared to earlier SH estimates over the coastal ocean, and suggests that the MC solutions could be a useful tool for understanding contemporary coastal sea level variability and change.
Other URLs: https://academic.oup.com/gji/article/214/2/1401/5000174
Delman, Andrew S.; Lee, Tong; Qiu, Bo (2018). Interannual to Multidecadal Forcing of Mesoscale Eddy Kinetic Energy in the Subtropical Southern Indian Ocean, Journal of Geophysical Research: Oceans, 10.1029/2018JC013945.
Title: Interannual to Multidecadal Forcing of Mesoscale Eddy Kinetic Energy in the Subtropical Southern Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Delman, Andrew S.; Lee, Tong; Qiu, Bo
Year: 2018
Formatted Citation: Delman, A. S., T. Lee, and B. Qiu, 2018: Interannual to Multidecadal Forcing of Mesoscale Eddy Kinetic Energy in the Subtropical Southern Indian Ocean. J. Geophys. Res. Ocean., doi:10.1029/2018JC013945
Abstract: A region of elevated mesoscale eddy activity spans the subtropical southern Indian Ocean (SSIO) between Madagascar and Australia. The interannual and decadal changes in eddy activity in the SSIO eddy band, as represented by the variability of eddy kinetic energy (EKE), have implications for the large-scale circulation, mixed-layer budgets, and biological activity. An analysis of nearly two and a half decades of sea level anomaly (SLA) data from merged satellite altimetry shows that, in the southeast Indian Ocean east of 90°E, the variations of EKE and SLA are positively correlated on interannual and decadal time scales. Moreover, EKE exhibits a multidecadal increasing linear trend that corresponds to an increasing trend of SLA in the region. The EKE-SLA covariability in the southeast Indian Ocean does not appear to be associated with a preference for anticyclonic over cyclonic eddy activity; rather, it can be attributed to the common remote forcing from the tropical Pacific associated with the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. In the west central SSIO, wind stress curl just south of the eddy band forces potential vorticity anomalies that affect conditions for instability in the west central SSIO; potential density and potential vorticity gradient anomalies also suggest a remote forcing mechanism originating in the region southwest of Australia. The interannual to multidecadal variability of EKE in the SSIO and its relationship with large-scale SLA has implications for mixed-layer dynamics and biogeochemistry and provides a basis for assessment of model simulations of eddy activity in the region.
Title: Interannual Eddy Kinetic Energy Modulations in the Agulhas Return Current
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Zhu, Yanan; Qiu, Bo; Lin, Xiaopei; Wang, Fan
Year: 2018
Formatted Citation: Zhu, Y., B. Qiu, X. Lin, and F. Wang, 2018: Interannual Eddy Kinetic Energy Modulations in the Agulhas Return Current. J. Geophys. Res. Ocean., 123(9), 6449-6462, doi:10.1029/2018JC014333
Abstract: Interannual variability in the mesoscale eddy field in the Agulhas Return Current (ARC) of 32-42°S and 15-35°E is investigated based on satellite altimeter observations and state estimate from the Estimating the Circulation and Climate of the Ocean, Phase II from 1993 to 2016. It is found that the interannual modulation of eddy kinetic energy in the ARC region is externally mediated by the wind stress forcing that generates the westward propagating sea surface height anomalies across the South Indian Ocean subtropical gyre. The wind-forced sea surface height anomalies influence the upstream Agulhas Current volume transports. By modulating the intensity of barotropic instability of the ARC mean flow centered around the retroflection region, the Agulhas Current inflow variability leads to the downstream interannual eddy kinetic energy fluctuations in the ARC region.
Formatted Citation: Chen, X., B. Qiu, S. Chen, X. Cheng, and Y. Qi, 2018: Interannual Modulations of the 50-Day Oscillations in the Celebes Sea: Dynamics and Impact. J. Geophys. Res. Ocean., 123(7), 4666-4679, doi:10.1029/2018JC013960
Abstract: Intense 50-day oscillations have been previously observed at the entrance of Celebes Sea, and their formation has been suggested to be a result of Rossby wave resonance where the frequency of cyclonic eddy shedding by the intruding Mindanao Current matches that of the gravest Rossby mode of the semienclosed Celebes Sea basin. Using the ocean state estimate of 1993-2016 from the Estimating the Circulation and Climate of the Ocean, Phase II, we detected strong interannual modulations in the shedding of cyclonic eddies at the Celebes Sea entrance. Active eddy sheddings occurred during 1993, 2002-2003, 2006-2010, and 2013-2015. Southward shifting of the wind-driven North Pacific tropical gyre and the concurrent strengthening of the Mindanao Current southeast of the Mindanao Island in these years are found to be inducive for the generation of cyclonic eddies intruding into the Celebes Sea. Modulated by the activity of eddy sheddings, the upper ocean water mass properties in both the Celebes Sea and Makassar Strait exhibit noticeable interannual changes with less saline waters appearing in the 75- to 175-m layer during the active eddy shedding years.
Formatted Citation: Wei, J., X. Zhang, and Z. Wang, 2018: Impacts of extratropical storm tracks on Arctic sea ice export through Fram Strait. Climate Dynamics, doi:10.1007/s00382-018-4254-8
Abstract: Studies have indicated regime shifts in atmospheric circulation, and associated changes in extratropical storm tracks and Arctic storm activity, in particular on the North Atlantic side of the Arctic Ocean. To improve understanding of changes in Arctic sea ice mass balance, we examined the impacts of the changed storm tracks and cyclone activity on Arctic sea ice export through Fram Strait by using a high resolution global ocean-sea ice model, MITgcm-ECCO2. The model was forced by the Japanese 25-year Reanalysis (JRA-25) dataset. The results show that storm-induced strong northerly wind stress can cause simultaneous response of daily sea ice export and, in turn, exert cumulative effects on interannual variability and long-term changes of sea ice export. Further analysis indicates that storm impact on sea ice export is spatially dependent. The storms occurring southeast of Fram Strait exhibit the largest impacts. The weakened intensity of winter (in this study winter is defined as October-March and summer as April-September) storms in this region after 1994/95 could be responsible for the decrease of total winter sea ice export during the same time period.
Hoteit, Ibrahim; Luo, Xiaodong; Bocquet, Marc; Kӧhl, Armin; Ait-El-Fquih, Boujemaa (2018). Data Assimilation in Oceanography: Current Status and New Directions, New Frontiers in Operational Oceanography, 465-511, 10.17125/gov2018.ch17.
Formatted Citation: Hoteit, I., X. Luo, M. Bocquet, A. Kӧhl, and B. Ait-El-Fquih, 2018: Data Assimilation in Oceanography: Current Status and New Directions. New Frontiers in Operational Oceanography, GODAE OceanView, 465-511, doi:10.17125/gov2018.ch17
Greene, Chad A.; Young, Duncan A.; Gwyther, David E.; Galton-Fenzi, Benjamin K.; Blankenship, Donald D. (2018). Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing, The Cryosphere, 9 (12), 2869-2882, 10.5194/tc-12-2869-2018.
Title: Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing
Type: Journal Article
Publication: The Cryosphere
Author(s): Greene, Chad A.; Young, Duncan A.; Gwyther, David E.; Galton-Fenzi, Benjamin K.; Blankenship, Donald D.
Year: 2018
Formatted Citation: Greene, C. A., D. A. Young, D. E. Gwyther, B. K. Galton-Fenzi, and D. D. Blankenship, 2018: Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing. Cryosph., 12(9), 2869-2882, doi:10.5194/tc-12-2869-2018
Abstract: Previous studies of Totten Ice Shelf have employed surface velocity measurements to estimate its mass balance and understand its sensitivities to interannual changes in climate forcing. However, displacement measurements acquired over timescales of days to weeks may not accurately characterize long-term flow rates wherein ice velocity fluctuates with the seasons. Quantifying annual mass budgets or analyzing interannual changes in ice velocity requires knowing when and where observations of glacier velocity could be aliased by subannual variability. Here, we analyze 16 years of velocity data for Totten Ice Shelf, which we generate at subannual resolution by applying feature-tracking algorithms to several hundred satellite image pairs. We identify a seasonal cycle characterized by a spring to autumn speedup of more than 100myr−1 close to the ice front. The amplitude of the seasonal cycle diminishes with distance from the open ocean, suggesting the presence of a resistive back stress at the ice front that is strongest in winter. Springtime acceleration precedes summer surface melt and is not attributable to thinning from basal melt. We attribute the onset of ice shelf acceleration each spring to the loss of buttressing from the breakup of seasonal landfast sea ice. ]]>
Liu, Junjie; Bowman, Kevin W.; Parazoo, Nicholas C; Bloom, A Anthony; Wunch, Debra; Jiang, Zhe; Gurney, Kevin R; Schimel, Dave (2018). Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations, Environmental Research Letters, 9 (13), 095003, 10.1088/1748-9326/aad5ef.
Title: Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations
Type: Journal Article
Publication: Environmental Research Letters
Author(s): Liu, Junjie; Bowman, Kevin W.; Parazoo, Nicholas C; Bloom, A Anthony; Wunch, Debra; Jiang, Zhe; Gurney, Kevin R; Schimel, Dave
Year: 2018
Formatted Citation: Liu, J., K. W. Bowman, N. C. Parazoo, A. A. Bloom, D. Wunch, Z. Jiang, K. R. Gurney, and D. Schimel, 2018: Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations. Environmental Research Letters, 13(9), 095003, doi:10.1088/1748-9326/aad5ef
Moteki, Qoosaku; Katsumata, Masaki; Yoneyama, Kunio; Ando, Kentaro; Hasegawa, Takuya (2018). Drastic thickening of the barrier layer off the western coast of Sumatra due to the Madden-Julian oscillation passage during the Pre-Years of the Maritime Continent campaign, Progress in Earth and Planetary Science, 1 (5), 35, 10.1186/s40645-018-0190-9.
Title: Drastic thickening of the barrier layer off the western coast of Sumatra due to the Madden-Julian oscillation passage during the Pre-Years of the Maritime Continent campaign
Type: Journal Article
Publication: Progress in Earth and Planetary Science
Formatted Citation: Moteki, Q., M. Katsumata, K. Yoneyama, K. Ando, and T. Hasegawa, 2018: Drastic thickening of the barrier layer off the western coast of Sumatra due to the Madden-Julian oscillation passage during the Pre-Years of the Maritime Continent campaign. Progress in Earth and Planetary Science, 5(1), 35, doi:10.1186/s40645-018-0190-9
Chen, Guo; Zhao, Qile; Wei, Na; Li, Min (2018). Effect of Helmert Transformation Parameters and Weight Matrix on Seasonal Signals in GNSS Coordinate Time Series, Sensors, 7 (18), 2127, 10.3390/s18072127.
Title: Effect of Helmert Transformation Parameters and Weight Matrix on Seasonal Signals in GNSS Coordinate Time Series
Type: Journal Article
Publication: Sensors
Author(s): Chen, Guo; Zhao, Qile; Wei, Na; Li, Min
Year: 2018
Formatted Citation: Chen, G., Q. Zhao, N. Wei, and M. Li, 2018: Effect of Helmert Transformation Parameters and Weight Matrix on Seasonal Signals in GNSS Coordinate Time Series. Sensors, 18(7), 2127, doi:10.3390/s18072127
Kumar, Anurag; Dwivedi, Suneet; Pandey, Avinash C. (2018). Quantifying predictability of sea ice around the Indian Antarctic stations using coupled ocean sea ice model with shelf ice, Polar Science (18), 83-93, 10.1016/j.polar.2018.04.003.
Title: Quantifying predictability of sea ice around the Indian Antarctic stations using coupled ocean sea ice model with shelf ice
Type: Journal Article
Publication: Polar Science
Author(s): Kumar, Anurag; Dwivedi, Suneet; Pandey, Avinash C.
Year: 2018
Formatted Citation: Kumar, A., S. Dwivedi, and A. C. Pandey, 2018: Quantifying predictability of sea ice around the Indian Antarctic stations using coupled ocean sea ice model with shelf ice. Polar Science, 18, 83-93, doi:10.1016/j.polar.2018.04.003
Title: Ocean forced variability of Totten Glacier mass loss
Type: Journal Article
Publication: Geological Society, London, Special Publications
Author(s): Roberts, Jason; Galton-Fenzi, Benjamin K.; Paolo, Fernando S.; Donnelly, Claire; Gwyther, David E.; Padman, Laurie; Young, Duncan; Warner, Roland; Greenbaum, Jamin; Fricker, Helen A.; Payne, Antony J.; Cornford, Stephen; Le Brocq, Anne; van Ommen, Tas; Blankenship, Don; Siegert, Martin J.
Year: 2018
Formatted Citation: Roberts, J. and Coauthors, 2018: Ocean forced variability of Totten Glacier mass loss. Geological Society, London, Special Publications, 461(1), 175-186, doi:10.1144/SP461.6
Formatted Citation: Zhao, X., D. Yuan, G. Yang, J. Wang, H. Liu, R. Zhang, and W. Han, 2018: Interannual variability and dynamics of intraseasonal wind rectification in the equatorial Pacific Ocean. Climate Dynamics, doi:10.1007/s00382-018-4383-0
Porter, David F.; Tinto, Kirsty J.; Boghosian, Alexandra L.; Csatho, Beata M.; Bell, Robin E.; Cochran, James R. (2018). Identifying Spatial Variability in Greenland’s Outlet Glacier Response to Ocean Heat, Frontiers in Earth Science (6), 10.3389/feart.2018.00090.
Title: Identifying Spatial Variability in Greenland’s Outlet Glacier Response to Ocean Heat
Type: Journal Article
Publication: Frontiers in Earth Science
Author(s): Porter, David F.; Tinto, Kirsty J.; Boghosian, Alexandra L.; Csatho, Beata M.; Bell, Robin E.; Cochran, James R.
Year: 2018
Formatted Citation: Porter, D. F., K. J. Tinto, A. L. Boghosian, B. M. Csatho, R. E. Bell, and J. R. Cochran, 2018: Identifying Spatial Variability in Greenland's Outlet Glacier Response to Ocean Heat. Frontiers in Earth Science, 6, doi:10.3389/feart.2018.00090
Title: Large-scale ocean connectivity and planktonic body size
Type: Journal Article
Publication: Nature Communications
Author(s): Villarino, Ernesto; Watson, James R.; Jönsson, Bror; Gasol, Josep M.; Salazar, Guillem; Acinas, Silvia G.; Estrada, Marta; Massana, Ramón; Logares, Ramiro; Giner, Caterina R.; Pernice, Massimo C.; Olivar, M. Pilar; Citores, Leire; Corell, Jon; Rodríguez-Ezpeleta, Naiara; Acuña, José Luis; Molina-Ramírez, Axayacatl; González-Gordillo, J. Ignacio; Cózar, Andrés; Martí, Elisa; Cuesta, José A.; Agustí, Susana; Fraile-Nuez, Eugenio; Duarte, Carlos M.; Irigoien, Xabier; Chust, Guillem
Year: 2018
Formatted Citation: Villarino, E. and Coauthors, 2018: Large-scale ocean connectivity and planktonic body size. Nature Communications, 9(1), 142, doi:10.1038/s41467-017-02535-8
Formatted Citation: Bashmachnikov, I., T. Belonenko, P. Kuibin, D. L. Volkov, and V. Foux, 2018: Pattern of vertical velocity in the Lofoten vortex (the Norwegian Sea). Ocean Dynamics, 68(12), 1711-1725, doi:10.1007/s10236-018-1213-1
Denvil-Sommer, Anna; Gehlen, Marion; Vrac, Mathieu; Mejia, Carlos (2018). FFNN-LSCE: A two-step neural network model for the reconstruction of surface ocean pCO2 over the Global Ocean, Geoscientific Model Development Discussions, 1-27, 10.5194/gmd-2018-247.
Title: FFNN-LSCE: A two-step neural network model for the reconstruction of surface ocean pCO2 over the Global Ocean
Type: Journal Article
Publication: Geoscientific Model Development Discussions
Author(s): Denvil-Sommer, Anna; Gehlen, Marion; Vrac, Mathieu; Mejia, Carlos
Year: 2018
Formatted Citation: Denvil-Sommer, A., M. Gehlen, M. Vrac, and C. Mejia, 2018: FFNN-LSCE: A two-step neural network model for the reconstruction of surface ocean pCO2 over the Global Ocean. Geoscientific Model Development Discussions, 1-27, doi:10.5194/gmd-2018-247
Abstract: A new Feed-Forward Neural Network (FFNN) model is presented to reconstruct surface ocean partial pressure of carbon dioxide (pCO2) over the global ocean. The model consists of two steps: (1) reconstruction of pCO2 climatology and (2) reconstruction of pCO2 anomalies with respect to the climatology. For the first step, a gridded climatology was used as the target, along with sea surface salinity and temperature (SSS and SST), sea surface height (SSH), chlorophyll a (Chl), mixed layer depth (MLD), as well as latitude and longitude as predictors. For the second step, data from the Surface Ocean CO2 Atlas (SOCAT) provided the target. The same set of predictors was used during step 2 augmented by their anomalies. During each step, the FFNN model reconstructs the non-linear relations between pCO2 and the ocean predictors. It provides monthly surface ocean pCO2 distributions on a 1ºx1º grid for the period 2001–2016. Global ocean pCO2 was reconstructed with a satisfying accuracy compared to independent observational data from SOCAT. However, errors are larger in regions with poor data coverage (e.g. Indian Ocean, Southern Ocean, subpolar Pacific). The model captured the strong interannual variability of surface ocean pCO2 with reasonable skills over the Equatorial Pacific associated with ENSO (El Niño Southern Oscillation). Our model was compared to three pCO2 mapping methods that participated in the Surface Ocean pCO2 Mapping intercomparison (SOCOM) initiative. We found a good agreement in seasonal and interannual variabilty between the models over the global ocean. However, important differences still exist at the regional scale, especially in the Southern hemisphere and in particular, the Southern Pacific and the Indian Ocean, as these regions suffer from poor data-coverage. Large regional uncertainties in reconstructed surface ocean pCO2 and sea-air CO2 fluxes have a strong influence on global estimates of CO2 fluxes and trends.
McParland, Erin L.; Levine, Naomi M. (2018). The role of differential DMSP production and community composition in predicting variability of global surface DMSP concentrations, Limnology and Oceanography, 10.1002/lno.11076.
Title: The role of differential DMSP production and community composition in predicting variability of global surface DMSP concentrations
Type: Journal Article
Publication: Limnology and Oceanography
Author(s): McParland, Erin L.; Levine, Naomi M.
Year: 2018
Formatted Citation: McParland, E. L., and N. M. Levine, 2018: The role of differential DMSP production and community composition in predicting variability of global surface DMSP concentrations. Limnology and Oceanography, doi:10.1002/lno.11076
Liu, Chengyan; Wang, Zhaomin; Cheng, Chen; Wu, Yang; Xia, Ruibin; Li, Bingrui; Li, Xiang (2018). On the Modified Circumpolar Deep Water Upwelling Over the Four Ladies Bank in Prydz Bay, East Antarctica, Journal of Geophysical Research: Oceans, 10.1029/2018JC014026.
Formatted Citation: Liu, C., Z. Wang, C. Cheng, Y. Wu, R. Xia, B. Li, and X. Li, 2018: On the Modified Circumpolar Deep Water Upwelling Over the Four Ladies Bank in Prydz Bay, East Antarctica. J. Geophys. Res. Ocean., doi:10.1029/2018JC014026
Yang, Peiran; Jing, Zhao; Wu, Lixin (2018). An Assessment of Representation of Oceanic Mesoscale Eddy-Atmosphere Interaction in the Current Generation of General Circulation Models and Reanalyses, Geophysical Research Letters, 21 (45), 11,856-11,865, 10.1029/2018GL080678.
Title: An Assessment of Representation of Oceanic Mesoscale Eddy-Atmosphere Interaction in the Current Generation of General Circulation Models and Reanalyses
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Yang, Peiran; Jing, Zhao; Wu, Lixin
Year: 2018
Formatted Citation: Yang, P., Z. Jing, and L. Wu, 2018: An Assessment of Representation of Oceanic Mesoscale Eddy-Atmosphere Interaction in the Current Generation of General Circulation Models and Reanalyses. Geophys. Res. Lett., 45(21), 11,856-11,865, doi:10.1029/2018GL080678
Mu, Longjiang; Losch, Martin; Yang, Qinghua; Ricker, Robert; Loza, Svetlana N.; Nerger, Lars (2018). Arctic-Wide Sea Ice Thickness Estimates From Combining Satellite Remote Sensing Data and a Dynamic Ice-Ocean Model with Data Assimilation During the CryoSat-2 Period, Journal of Geophysical Research: Oceans, 10.1029/2018JC014316.
Title: Arctic-Wide Sea Ice Thickness Estimates From Combining Satellite Remote Sensing Data and a Dynamic Ice-Ocean Model with Data Assimilation During the CryoSat-2 Period
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Formatted Citation: Mu, L., M. Losch, Q. Yang, R. Ricker, S. N. Loza, and L. Nerger, 2018: Arctic-Wide Sea Ice Thickness Estimates From Combining Satellite Remote Sensing Data and a Dynamic Ice-Ocean Model with Data Assimilation During the CryoSat-2 Period. J. Geophys. Res. Ocean., doi:10.1029/2018JC014316
Ungermann, Mischa; Losch, Martin (2018). An Observationally Based Evaluation of Subgrid Scale Ice Thickness Distributions Simulated in a Large-Scale Sea Ice-Ocean Model of the Arctic Ocean, Journal of Geophysical Research: Oceans, 10.1029/2018JC014022.
Title: An Observationally Based Evaluation of Subgrid Scale Ice Thickness Distributions Simulated in a Large-Scale Sea Ice-Ocean Model of the Arctic Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Ungermann, Mischa; Losch, Martin
Year: 2018
Formatted Citation: Ungermann, M., and M. Losch, 2018: An Observationally Based Evaluation of Subgrid Scale Ice Thickness Distributions Simulated in a Large-Scale Sea Ice-Ocean Model of the Arctic Ocean. J. Geophys. Res. Ocean., doi:10.1029/2018JC014022
Lyu, Yilong; Li, Yuanlong; Tang, Xiaohui; Wang, Fan; Wang, Jianing (2018). Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997-1998 and 2015-2016 El Niño Events, Geophysical Research Letters, 18 (45), 9748-9756, 10.1029/2018GL078915.
Formatted Citation: Lyu, Y., Y. Li, X. Tang, F. Wang, and J. Wang, 2018: Contrasting Intraseasonal Variations of the Equatorial Pacific Ocean Between the 1997-1998 and 2015-2016 El Niño Events. Geophys. Res. Lett., 45(18), 9748-9756, doi:10.1029/2018GL078915
Hartfield, Gail; Blunden, Jessica; Arndt, Derek S. (2018). State of the Climate in 2017, Bulletin of the American Meteorological Society, 8 (99), Si-S310, 10.1175/2018BAMSStateoftheClimate.1.
Publication: Bulletin of the American Meteorological Society
Author(s): Hartfield, Gail; Blunden, Jessica; Arndt, Derek S.
Year: 2018
Formatted Citation: Hartfield, G., J. Blunden, and D. S. Arndt, 2018: State of the Climate in 2017. Bull. Am. Meteorol. Soc., 99(8), Si-S310, doi:10.1175/2018BAMSStateoftheClimate.1
Formatted Citation: Andrei, C., S. Lahtinen, M. Nordman, J. Näränen, H. Koivula, M. Poutanen, and J. Hyyppä, 2018: GPS Time Series Analysis from Aboa the Finnish Antarctic Research Station. Remote Sensing, 10(12), 1937, doi:10.3390/rs10121937
Abstract: Continuous Global Positioning System (GPS) observations have been logged at the Finnish Antarctic research station (Aboa) since February 2003. The station is located in Dronning Maud Land, East Antarctica. Almost 5000 daily observation files have been archived based on yearly scientific expeditions. These files have not been fully analysed until now. This study reports for the first time on the consistent and homogeneous data processing and analysis of the 15-year long time series. Daily coordinates are obtained using Precise Point Positioning (PPP) processing based on two approaches. The first approach is based on the Kalman filter and uses the RTKLIB open source library to produce daily solutions by unconventionally running the filter in the forward and backward direction. The second approach uses APPS web service and is based on GIPSY scientific processing engine. The two approaches show an excellent agreement with less than 3 mm rms error horizontally and 6 mm rms error vertically. The derived position time series is analysed in terms of trend, periodicity and noise characteristics. The noise of the time series was found to be power-law noise model with spectral index closer to flicker noise. In addition, several periodic signals were found at 5, 14, 183 and 362 days. Furthermore, most of the horizontal movement was found to be in the North direction at a rate of 11.23 ± 0.09 mm/y, whereas the rate in the East direction was estimated to be 1.46 ± 0.05 mm/y. Lastly, the 15-year long time series revealed a movement upwards at a rate of 0.79 ± 0.35 mm/y. Despite being an unattended station, Aboa provides one of the most continuous and longest GPS time series in Antarctica. Therefore, we believe that this research increases the awareness of local geophysical phenomena in a less reported area of the Antarctic continent.
Gregor, Luke; Kok, Schalk; Monteiro, Pedro M. S. (2018). Interannual drivers of the seasonal cycle of CO2 in the Southern Ocean, Biogeosciences, 8 (15), 2361-2378, 10.5194/bg-15-2361-2018.
Title: Interannual drivers of the seasonal cycle of CO2 in the Southern Ocean
Type: Journal Article
Publication: Biogeosciences
Author(s): Gregor, Luke; Kok, Schalk; Monteiro, Pedro M. S.
Year: 2018
Formatted Citation: Gregor, L., S. Kok, and P. M. S. Monteiro, 2018: Interannual drivers of the seasonal cycle of CO2 in the Southern Ocean. Biogeosciences, 15(8), 2361-2378, doi:10.5194/bg-15-2361-2018
Abstract: Resolving and understanding the drivers of variability of CO2 in the Southern Ocean and its potential climate feedback is one of the major scientific challenges of the ocean-climate community. Here we use a regional approach on empirical estimates of pCO2 to understand the role that seasonal variability has in long-term CO2 changes in the Southern Ocean. Machine learning has become the preferred empirical modelling tool to interpolate time- and location-restricted ship measurements of pCO2. In this study we use an ensemble of three machine-learning products: support vector regression (SVR) and random forest regression (RFR) from Gregor et al. (2017), and the self-organising-map feed-forward neural network (SOM-FFN) method from Landschützer et al. (2016). The interpolated estimates of ΔpCO2 are separated into nine regions in the Southern Ocean defined by basin (Indian, Pacific, and Atlantic) and biomes (as defined by Fay and McKinley, 2014a). The regional approach shows that, while there is good agreement in the overall trend of the products, there are periods and regions where the confidence in estimated ΔpCO2 is low due to disagreement between the products. The regional breakdown of the data highlighted the seasonal decoupling of the modes for summer and winter interannual variability. Winter interannual variability had a longer mode of variability compared to summer, which varied on a 4-6-year timescale. We separate the analysis of the ΔpCO2 and its drivers into summer and winter. We find that understanding the variability of ΔpCO2 and its drivers on shorter timescales is critical to resolving the long-term variability of ΔpCO2. Results show that ΔpCO2 is rarely driven by thermodynamics during winter, but rather by mixing and stratification due to the stronger correlation of ΔpCO2 variability with mixed layer depth. Summer pCO2 variability is consistent with chlorophyll a variability, where higher concentrations of chlorophyll a correspond with lower pCO2 concentrations. In regions of low chlorophyll a concentrations, wind stress and sea surface temperature emerged as stronger drivers of ΔpCO2. In summary we propose that sub-decadal variability is explained by summer drivers, while winter variability contributes to the long-term changes associated with the SAM. This approach is a useful framework to assess the drivers of ΔpCO2 but would greatly benefit from improved estimates of ΔpCO2 and a longer time series.
Schlegel, Nicole-Jeanne; Seroussi, Hélène; Schodlok, Michael P.; Larour, Eric Y.; Boening, Carmen; Limonadi, Daniel; Watkins, Michael M.; Morlighem, Mathieu; van den Broeke, Michiel R. (2018). Exploration of Antarctic Ice Sheet 100-year contribution to sea level rise and associated model uncertainties using the ISSM framework, The Cryosphere, 11 (12), 3511-3534, 10.5194/tc-12-3511-2018.
Title: Exploration of Antarctic Ice Sheet 100-year contribution to sea level rise and associated model uncertainties using the ISSM framework
Type: Journal Article
Publication: The Cryosphere
Author(s): Schlegel, Nicole-Jeanne; Seroussi, Hélène; Schodlok, Michael P.; Larour, Eric Y.; Boening, Carmen; Limonadi, Daniel; Watkins, Michael M.; Morlighem, Mathieu; van den Broeke, Michiel R.
Year: 2018
Formatted Citation: Schlegel, N. and Coauthors, 2018: Exploration of Antarctic Ice Sheet 100-year contribution to sea level rise and associated model uncertainties using the ISSM framework. Cryosph., 12(11), 3511-3534, doi:10.5194/tc-12-3511-2018
Abstract: Estimating the future evolution of the Antarctic Ice Sheet (AIS) is critical for improving future sea level rise (SLR) projections. Numerical ice sheet models are invaluable tools for bounding Antarctic vulnerability; yet, few continental-scale projections of century-scale AIS SLR contribution exist, and those that do vary by up to an order of magnitude. This is partly because model projections of future sea level are inherently uncertain and depend largely on the model's boundary conditions and climate forcing, which themselves are unknown due to the uncertainty in the projections of future anthropogenic emissions and subsequent climate response. Here, we aim to improve the understanding of how uncertainties in model forcing and boundary conditions affect ice sheet model simulations. With use of sampling techniques embedded within the Ice Sheet System Model (ISSM) framework, we assess how uncertainties in snow accumulation, ocean-induced melting, ice viscosity, basal friction, bedrock elevation, and the presence of ice shelves impact continental-scale 100-year model simulations of AIS future sea level contribution. Overall, we find that AIS sea level contribution is strongly affected by grounding line retreat, which is driven by the magnitude of ice shelf basal melt rates and by variations in bedrock topography. In addition, we find that over 1.2m of AIS global mean sea level contribution over the next century is achievable, but not likely, as it is tenable only in response to unrealistically large melt rates and continental ice shelf collapse. Regionally, we find that under our most extreme 100-year warming experiment generalized for the entire ice sheet, the Amundsen Sea sector is the most significant source of model uncertainty (1032mm 6σ spread) and the region with the largest potential for future sea level contribution (297mm). In contrast, under a more plausible forcing informed regionally by literature and model sensitivity studies, the Ronne basin has a greater potential for local increases in ice shelf basal melt rates. As a result, under this more likely realization, where warm waters reach the continental shelf under the Ronne ice shelf, it is the Ronne basin, particularly the Evans and Rutford ice streams, that are the greatest contributors to potential SLR (161mm) and to simulation uncertainty (420mm 6σ spread). ]]>
Naughten, Kaitlin A.; Meissner, Katrin J.; Galton-Fenzi, Benjamin K.; England, Matthew H.; Timmermann, Ralph; Hellmer, Hartmut H. (2018). Future Projections of Antarctic Ice Shelf Melting Based on CMIP5 Scenarios, Journal of Climate, 13 (31), 5243-5261, 10.1175/JCLI-D-17-0854.1.
Title: Future Projections of Antarctic Ice Shelf Melting Based on CMIP5 Scenarios
Type: Journal Article
Publication: Journal of Climate
Author(s): Naughten, Kaitlin A.; Meissner, Katrin J.; Galton-Fenzi, Benjamin K.; England, Matthew H.; Timmermann, Ralph; Hellmer, Hartmut H.
Year: 2018
Formatted Citation: Naughten, K. A., K. J. Meissner, B. K. Galton-Fenzi, M. H. England, R. Timmermann, and H. H. Hellmer, 2018: Future Projections of Antarctic Ice Shelf Melting Based on CMIP5 Scenarios. J. Clim., 31(13), 5243-5261, doi:10.1175/JCLI-D-17-0854.1
Gruszczynska, Marta; Rosat, Severine; Klos, Anna; Gruszczynski, Maciej; Bogusz, Janusz (2018). Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations, Pure and Applied Geophysics, 5 (175), 1805-1822, 10.1007/s00024-018-1814-0.
Formatted Citation: Gruszczynska, M., S. Rosat, A. Klos, M. Gruszczynski, and J. Bogusz, 2018: Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations. Pure and Applied Geophysics, 175(5), 1805-1822, doi:10.1007/s00024-018-1814-0
Mohammadi-Aragh, M.; Goessling, H. F.; Losch, Martin; Hutter, N.; Jung, T. (2018). Predictability of Arctic sea ice on weather time scales, Scientific Reports, 1 (8), 6514, 10.1038/s41598-018-24660-0.
Title: Predictability of Arctic sea ice on weather time scales
Type: Journal Article
Publication: Scientific Reports
Author(s): Mohammadi-Aragh, M.; Goessling, H. F.; Losch, Martin; Hutter, N.; Jung, T.
Year: 2018
Formatted Citation: Mohammadi-Aragh, M., H. F. Goessling, M. Losch, N. Hutter, and T. Jung, 2018: Predictability of Arctic sea ice on weather time scales. Scientific Reports, 8(1), 6514, doi:10.1038/s41598-018-24660-0
Chi, Lequan; Wolfe, Christopher L.P.; Hameed, Sultan (2018). Intercomparison of the Gulf Stream in ocean reanalyses: 1993−2010, Ocean Modelling (125), 1-21, 10.1016/j.ocemod.2018.02.008.
Title: Intercomparison of the Gulf Stream in ocean reanalyses: 1993−2010
Type: Journal Article
Publication: Ocean Modelling
Author(s): Chi, Lequan; Wolfe, Christopher L.P.; Hameed, Sultan
Year: 2018
Formatted Citation: Chi, L., C. L. Wolfe, and S. Hameed, 2018: Intercomparison of the Gulf Stream in ocean reanalyses: 1993−2010. Ocean Modelling, 125, 1-21, doi:10.1016/j.ocemod.2018.02.008
Pianezze, J.; Barthe, C.; Bielli, S.; Tulet, P.; Jullien, S.; Cambon, G.; Bousquet, O.; Claeys, M.; Cordier, E. (2018). A New Coupled Ocean-Waves-Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013-2014) in the South-West Indian Ocean, Journal of Advances in Modeling Earth Systems, 3 (10), 801-825, 10.1002/2017MS001177.
Title: A New Coupled Ocean-Waves-Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013-2014) in the South-West Indian Ocean
Type: Journal Article
Publication: Journal of Advances in Modeling Earth Systems
Author(s): Pianezze, J.; Barthe, C.; Bielli, S.; Tulet, P.; Jullien, S.; Cambon, G.; Bousquet, O.; Claeys, M.; Cordier, E.
Year: 2018
Formatted Citation: Pianezze, J. and Coauthors, 2018: A New Coupled Ocean-Waves-Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013-2014) in the South-West Indian Ocean. Journal of Advances in Modeling Earth Systems, 10(3), 801-825, doi:10.1002/2017MS001177
Triest, Ludwig; Sierens, Tim; Menemenlis, Dimitris; Van der Stocken, Tom (2018). Inferring Connectivity Range in Submerged Aquatic Populations (Ruppia L.) Along European Coastal Lagoons From Genetic Imprint and Simulated Dispersal Trajectories, Frontiers in Plant Science (9), 10.3389/fpls.2018.00806.
Title: Inferring Connectivity Range in Submerged Aquatic Populations (Ruppia L.) Along European Coastal Lagoons From Genetic Imprint and Simulated Dispersal Trajectories
Type: Journal Article
Publication: Frontiers in Plant Science
Author(s): Triest, Ludwig; Sierens, Tim; Menemenlis, Dimitris; Van der Stocken, Tom
Year: 2018
Formatted Citation: Triest, L., T. Sierens, D. Menemenlis, and T. Van der Stocken, 2018: Inferring Connectivity Range in Submerged Aquatic Populations (Ruppia L.) Along European Coastal Lagoons From Genetic Imprint and Simulated Dispersal Trajectories. Front. Plant Sci., 9, doi:10.3389/fpls.2018.00806
Formatted Citation: Guo, Y., X. Lin, M. Wei, C. Liu, and G. Men, 2018: Decadal Variability of North Pacific Eastern Subtropical Mode Water. J. Geophys. Res. Ocean., 123(9), 6189-6206, doi:10.1029/2018JC013890
Formatted Citation: Mouyen, M., L. Longuevergne, P. Steer, A. Crave, J. Lemoine, H. Save, and C. Robin, 2018: Assessing modern river sediment discharge to the ocean using satellite gravimetry. Nature Communications, 9(1), 3384, doi:10.1038/s41467-018-05921-y
Mazloff, M. R.; Cornuelle, B. D.; Gille, S. T.; Verdy, A. (2018). Correlation Lengths for Estimating the Large-Scale Carbon and Heat Content of the Southern Ocean, Journal of Geophysical Research: Oceans, 2 (123), 883-901, 10.1002/2017JC013408.
Title: Correlation Lengths for Estimating the Large-Scale Carbon and Heat Content of the Southern Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Mazloff, M. R.; Cornuelle, B. D.; Gille, S. T.; Verdy, A.
Year: 2018
Formatted Citation: Mazloff, M. R., B. D. Cornuelle, S. T. Gille, and A. Verdy, 2018: Correlation Lengths for Estimating the Large-Scale Carbon and Heat Content of the Southern Ocean. J. Geophys. Res. Ocean., 123(2), 883-901, doi:10.1002/2017JC013408
Rocha, Cesar B. (2018). The turbulent and wavy upper ocean: transition from geostrophic flows to internal waves and stimulated generation of near-inertial waves.
Title: The turbulent and wavy upper ocean: transition from geostrophic flows to internal waves and stimulated generation of near-inertial waves
Type: Thesis
Publication:
Author(s): Rocha, Cesar B.
Year: 2018
Formatted Citation: Rocha, C. B., 2018: The turbulent and wavy upper ocean: transition from geostrophic flows to internal waves and stimulated generation of near-inertial waves., 217 pp. https://escholarship.org/uc/item/4m893890.
Abstract: We study the mesoscale to submesoscale (10-300 km) dynamics of the upper ocean, with particular attention to the partitioning between geostrophic flows and in- ternal waves, and the interaction between these two types of flow. Using 13 years of shipboard ADCP transects in Drake Passage, we show that internal waves account for more than half of the upper-ocean kinetic energy at scales between 10-40 km; a transi- tion from the dominance of geostrophic flow to inertia-gravity waves occurs at 40 km. We further show that a global numerical model with embedded tides reproduces this partitioning between upper-ocean geostrophic flows and inertia-gravity waves. Using the output of this model, we show that in the Kuroshio Extension upper-ocean sub- mesoscale (10-100 km) geostrophic flow and inertia-gravity waves undergo vigorous seasonal cycles that are out of phase: geostrophic flows peak in late winter/early spring, while the projection of inertia-gravity waves at the surface peaks in late summer/early fall. The observational and modeling evidence of the importance of both geostrophic flows and internal gravity waves at mesoscales to submesoscales hints on the interaction between these two types of flow. To better understand these interactions, we analyze a simple model that couples barotropic quasi-geostrophic flow and near-inertial waves. There are two mechanisms of energy transfer from geostrophic flow to externally forced near-inertial waves: the refractive convergence of the wave action density into anti- cyclones (and divergence from cyclones); and the enhancement of wave-field gradients by geostrophic straining. Unforced inviscid numerical solutions of this reduced model reveal that geostrophic straining accounts for most of stimulated generation, which represents 10-20% of the decay of the initial balanced energy. Consideration of the dissipative problem reveals that wave dissipation generates both quasi-geostrophic po- tential vorticity locally and geostrophic kinetic energy. This wave streaming mechanism is non-negligible in forced-dissipative solutions, which equilibrate even without bottom drag. In a separate study, we derive a Galerkin approximation for the surface-active quasi-geostrophic system using standard vertical modes. While the Galerkin expansions of streamfunction and potential vorticity do not satisfy the inversion relation exactly, the series converge with no Gibbs oscillations. With enough modes, the Galerkin series provide a good approximation to the streamfunction throughout the domain, which can be used to advect potential vorticity in the interior and buoyancy at the surfaces.
Formatted Citation: Mu, L., Q. Yang, M. Losch, S. N. Losa, R. Ricker, L. Nerger, and X. Liang, 2018: Improving sea ice thickness estimates by assimilating CryoSat-2 and SMOS sea ice thickness data simultaneously. Quarterly Journal of the Royal Meteorological Society, 144(711), 529-538, doi:10.1002/qj.3225
Title: Properties, Mechanisms and Predictability of Eddies in the Red Sea
Type: Thesis
Publication:
Author(s): Zhan, Peng
Year: 2018
Formatted Citation: Zhan, P., 2018: Properties, Mechanisms and Predictability of Eddies in the Red Sea., 163 pp. doi:10.25781/KAUST-1IARG.
Abstract: Eddies are one of the key features of the Red Sea circulation. They are not only crucial for energy conversion among dynamics at different scales, but also for materials transport across the basin. This thesis focuses on studying the characteristics of Red Sea eddies, including their temporal and spatial properties, their energy budget, the mechanisms of their evolution, and their predictability. Remote sensing data, in-situ observations, the oceanic general circulation model, and data assimilation techniques were employed in this thesis. The eddies in the Red Sea were first identified using altimeter data by applying an improved winding-angle method, based on which the statistical properties of those eddies were derived. The results suggested that eddies occur more frequently in the central basin of the Red Sea and exhibit a significant seasonal variation. The mechanisms of the eddies' evolution, particularly the eddy kinetic energy budget, were then investigated based on the outputs of a long-term eddy resolving numerical model configured for the Red Sea with realistic forcing. Examination of the energy budget revealed that the eddies acquire the vast majority of kinetic energy through conversion of eddy available potential energy via baroclinic instability, which is intensified during winter. The possible factors modulating the behavior of the several observed eddies in the Red Sea were then revealed by conducting a sensitivity analysis using the adjoint model. These eddies were found to exhibit different sensitivities to external forcings, suggesting different mechanisms for their evolution. This is the first known adjoint sensitivity study on specific eddy events in the Red Sea and was hitherto not previously appreciated. The last chapter examines the predictability of Red Sea eddies using an ensemble-based forecasting and assimilation system. The forecast sea surface height was used to evaluate the overall performance of the short-term eddy predictability. Different ensemble sampling schemes were implemented, and the investigation among different schemes is followed by a discussion of performance and challenges based on the results of a case study. The thesis not only enhances understanding of the Red Sea dynamics, but also deepens knowledge of the physical-biological and air-sea interactions within the basin. Further, it is a stepping stone to building a robust regional operational system with refined forecasting skills.
Formatted Citation: Yang, H., B. Qiu, P. Chang, L. Wu, S. Wang, Z. Chen, and Y. Yang, 2018: Decadal Variability of Eddy Characteristics and Energetics in the Kuroshio Extension: Unstable Versus Stable States. J. Geophys. Res. Ocean., 123(9), 6653-6669, doi:10.1029/2018JC014081
Mukherjee, A.; Shankar, D.; Chatterjee, Abhisek; Vinayachandran, P. N. (2018). Numerical simulation of the observed near-surface East India Coastal Current on the continental slope, Climate Dynamics, 11-12 (50), 3949-3980, 10.1007/s00382-017-3856-x.
Title: Numerical simulation of the observed near-surface East India Coastal Current on the continental slope
Type: Journal Article
Publication: Climate Dynamics
Author(s): Mukherjee, A.; Shankar, D.; Chatterjee, Abhisek; Vinayachandran, P. N.
Year: 2018
Formatted Citation: Mukherjee, A., D. Shankar, A. Chatterjee, and P. N. Vinayachandran, 2018: Numerical simulation of the observed near-surface East India Coastal Current on the continental slope. Climate Dynamics, 50(11-12), 3949-3980, doi:10.1007/s00382-017-3856-x
Title: Improving the Coastal Mean Dynamic Topography by Geodetic Combination of Tide Gauge and Satellite Altimetry
Type: Journal Article
Publication: Marine Geodesy
Author(s): Andersen, Ole Baltazar; Nielsen, Karina; Knudsen, Per; Hughes, Chris W.; Bingham, Rory; Fenoglio-Marc, Luciana; Gravelle, Médéric; Kern, Michael; Polo, Sara Padilla
Year: 2018
Formatted Citation: Andersen, O. B. and Coauthors, 2018: Improving the Coastal Mean Dynamic Topography by Geodetic Combination of Tide Gauge and Satellite Altimetry. Marine Geodesy, 1-29, doi:10.1080/01490419.2018.1530320
Kumar, Ravi Prakash; Nigam, Tanuja; Pant, Vimlesh (2018). Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere-ocean-wave model, Ocean Science, 2 (14), 259-272, 10.5194/os-14-259-2018.
Title: Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere-ocean-wave model
Type: Journal Article
Publication: Ocean Science
Author(s): Kumar, Ravi Prakash; Nigam, Tanuja; Pant, Vimlesh
Year: 2018
Formatted Citation: Kumar, R. P., T. Nigam, and V. Pant, 2018: Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere-ocean-wave model. Ocean Science, 14(2), 259-272, doi:10.5194/os-14-259-2018
Abstract: A coupled atmosphere-ocean-wave model was used to examine mixing in the upper-oceanic layers under the influence of a very severe cyclonic storm Phailin over the Bay of Bengal (BoB) during 10-14 October 2013. The coupled model was found to improve the sea surface temperature over the uncoupled model. Model simulations highlight the prominent role of cyclone-induced near-inertial oscillations in subsurface mixing up to the thermocline depth. The inertial mixing introduced by the cyclone played a central role in the deepening of the thermocline and mixed layer depth by 40 and 15m, respectively. For the first time over the BoB, a detailed analysis of inertial oscillation kinetic energy generation, propagation, and dissipation was carried out using an atmosphere-ocean-wave coupled model during a cyclone. A quantitative estimate of kinetic energy in the oceanic water column, its propagation, and its dissipation mechanisms were explained using the coupled atmosphere-ocean-wave model. The large shear generated by the inertial oscillations was found to overcome the stratification and initiate mixing at the base of the mixed layer. Greater mixing was found at the depths where the eddy kinetic diffusivity was large. The baroclinic current, holding a larger fraction of kinetic energy than the barotropic current, weakened rapidly after the passage of the cyclone. The shear induced by inertial oscillations was found to decrease rapidly with increasing depth below the thermocline. The dampening of the mixing process below the thermocline was explained through the enhanced dissipation rate of turbulent kinetic energy upon approaching the thermocline layer. The wave-current interaction and nonlinear wave-wave interaction were found to affect the process of downward mixing and cause the dissipation of inertial oscillations.
Formatted Citation: Vaňková, I., 2018: Ice and Ocean Dynamics in a Glacier Fjord., 178 pp. https://drive.google.com/file/d/1BwrgBIl8jpqld8nKl6ldtyF1qRhfPRzT/view?usp=sharingl%0A.
Abstract: This dissertation consists of four topics in the dynamics of glacier fjords: (1) sources of hydrographic variability in deep glacier fjord waters, (2) dynamic interactions within the ice mélange, (3) englacial hydrology at a marine-terminating glacier, and (4) calving generated ocean waves. Greenland's fjords play the important role of connecting glacier termini with the con- tinental shelf and exposing them to oceanic variability, affecting ice-sheet stability via variable melt rates at the ice-ocean interface. Observations collected in Sermilik Fjord were used to identify timescales of hydrographic variability of deep, warm waters and an ocean state estimate was used to identify sources of this variability. It is shown that inter- annual variability is set by the extent of deep convection in the Irminger Sea. Furthermore, it is found that seasonal variability in fjord density is introduced at the continental shelf break by Ekman transport, which in turn governs seasonal variability of the fjord's deep hydrographic properties due to the presence of vertical temperature and salinity gradients. The ice mélange is a mixture of sea ice and icebergs, which can be important for glacier stability, due to its potential to provide backstress via buttressing, preventing calving. A new approach to modeling the ice mélange is developed here. The rheology of an existing continuum sea-ice model is modified to incorporate the mechanical effect of icebergs and a semi-Lagrangian time-stepping scheme is adopted to preserve iceberg shape through time. Meltwater transport through glaciers affects material properties of glacial ice and controls the ice flow by setting its boundary conditions. However, since the glacial interior is under-observed in both space and time, little is known about how this meltwater trans- port occurs. New observations of the glacier interior showed a diurnal signal consistent with the existence of an englacial diurnal meltwater cycle, indicating a dense and complex hydrologic network inside the glacier. Barotropic waves in glacier fjords and their relation to calving were explored. Observa- tional data from high-frequency pressure sensors placed in an array on the fjord sea floor captured tsunamis which were proceeded by large calving events. A numerical model was used to infer the forcing at the glacier-ocean boundary producing these tsunamis, yielding a timescale over which calving at Helheim Glacier occurs.
Foukal, Nicholas P; Lozier, M Susan (2018). Examining the Origins of Ocean Heat Content Variability in the Eastern North Atlantic Subpolar Gyre, Geophysical Research Letters, 20 (45), 11,211-275,283, 10.1029/2018GL079122.
Title: Examining the Origins of Ocean Heat Content Variability in the Eastern North Atlantic Subpolar Gyre
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Foukal, Nicholas P; Lozier, M Susan
Year: 2018
Formatted Citation: Foukal, N. P., and M. S. Lozier, 2018: Examining the Origins of Ocean Heat Content Variability in the Eastern North Atlantic Subpolar Gyre. Geophys. Res. Lett., 45(20), 11,211-275,283, doi:10.1029/2018GL079122
Abstract: We analyze sources of ocean heat content (OHC) variability in the eastern North Atlantic subpolar gyre from both Eulerian and Lagrangian perspectives within two ocean simulations from 1990 to 2015. Heat budgets reveal that while the OHC seasonal cycle is driven by air-sea fluxes, interannual OHC variability is driven by both air-sea fluxes and the divergence of ocean heat transport, the latter of which is dominated by the oceanic flux through the southern face of the study area. Lagrangian trajectories initialized along the southern face and run backward in time indicate that interannual variability in the subtropical-origin volume flux (i.e., the upper limb of the overturning circulation) drives variability in the temperature flux through the southern face. As such, the heat carried by the imported subtropical waters is an important component of the eastern subpolar gyre heat budget on interannual time scales.
Hameed, Sultan; Wolfe, Christopher L P; Chi, Lequan (2018). Impact of the Atlantic Meridional Mode on Gulf Stream North Wall Position, Journal of Climate, 21 (31), 8875-8894, 10.1175/JCLI-D-18-0098.1.
Title: Impact of the Atlantic Meridional Mode on Gulf Stream North Wall Position
Type: Journal Article
Publication: Journal of Climate
Author(s): Hameed, Sultan; Wolfe, Christopher L P; Chi, Lequan
Year: 2018
Formatted Citation: Hameed, S., C. L. P. Wolfe, and L. Chi, 2018: Impact of the Atlantic Meridional Mode on Gulf Stream North Wall Position. J. Clim., 31(21), 8875-8894, doi:10.1175/JCLI-D-18-0098.1
Abstract: The path of the Gulf Stream as it leaves the continental shelf near Cape Hatteras is marked by a sharp gradient in ocean temperature known as the North Wall. Previous work in the literature has considered processes related to the North Atlantic Oscillation (NAO) in triggering latitudinal displacements of the North Wall position. This paper presents evidence that the Atlantic meridional mode (AMM) also impacts interannual variations of the North Wall position. The AMM signal from the tropics propagates to the Gulf Stream near the 200-m depth, and there are two time scales for this interaction. Anomalous Ekman suction induced by AMM cools the tropical Atlantic. The cold water in the Caribbean Sea is entrained into the currents feeding the Gulf Stream, and this cooling signal reaches the North Wall within a year. A second mechanism involves cold anomalies in the western tropical Atlantic, which initially propagate westward as baroclinic planetary waves, reaching the Gulf Stream and resulting in a southward shift in the North Wall position after a delay of about one year. In an analysis for the period 1961-2015, AMM's signal dominates North Wall fluctuations in the upper 300 m, while NAO is the major influence below ~500 m; the influence of both the teleconnections is seen between 300 and 500 m. The relationship between the Atlantic meridional overturning circulation (AMOC) and the North Wall is investigated for the 2005-15 period and found to be statistically significant only at the sea surface in one of the three North Wall indices used.
Filmer, M. S.; Hughes, C. W.; Woodworth, P. L.; Featherstone, W. E.; Bingham, R. J. (2018). Comparison between geodetic and oceanographic approaches to estimate mean dynamic topography for vertical datum unification: evaluation of Australian tide gauges, Journal of Geodesy, 12 (92), 1413-1437.
Title: Comparison between geodetic and oceanographic approaches to estimate mean dynamic topography for vertical datum unification: evaluation of Australian tide gauges
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Filmer, M. S.; Hughes, C. W.; Woodworth, P. L.; Featherstone, W. E.; Bingham, R. J.
Year: 2018
Formatted Citation: Filmer, M. S., C. W. Hughes, P. L. Woodworth, W. E. Featherstone, and R. J. Bingham, 2018: Comparison between geodetic and oceanographic approaches to estimate mean dynamic topography for vertical datum unification: evaluation of Australian tide gauges. Journal of Geodesy, 92(12), 1413-1437, https://link.springer.com/article/10.1007/s00190-018-1131-5
Author(s): Zhang, Hong; Menemenlis, Dimitris; Fenty, Ian
Year: 2018
Formatted Citation: Zhang, H., D. Menemenlis, and I. Fenty, 2018: ECCO LLC270 Ocean-Ice State Estimate., 7 pp. doi:1721.1/119821.
Abstract: This document provides a brief introduction to ECCO LLC270, an ongoing global ocean- ice state estimate. As a pilot experiment, the first ECCO LLC270 product covers the time-period of 2001 to 2015 (later extended to 2017). This is particularly useful for ocean-ice sheet interaction studies. Extension back to 1992 is underway.
Keywords: Ocean Data Assimilation, Ocean State Estimation
Other URLs: https://dspace.mit.edu/handle/1721.1/117188
Prowe, A. E. Friederike; Visser, André W.; Andersen, Ken H.; Chiba, Sanae; Kiørboe, Thomas (2018). Biogeography of zooplankton feeding strategy, Limnology and Oceanography, lno.11067, 10.1002/lno.11067.
Title: Biogeography of zooplankton feeding strategy
Type: Journal Article
Publication: Limnology and Oceanography
Author(s): Prowe, A. E. Friederike; Visser, André W.; Andersen, Ken H.; Chiba, Sanae; Kiørboe, Thomas
Year: 2018
Formatted Citation: Prowe, A. E. F., A. W. Visser, K. H. Andersen, S. Chiba, and T. Kiørboe, 2018: Biogeography of zooplankton feeding strategy. Limnology and Oceanography, lno.11067, doi:10.1002/lno.11067
Title: Simulated impact of Southern Hemisphere westerlies on Antarctic Shelf Bottom Water temperature
Type: Journal Article
Publication: Advances in Polar Science
Author(s): Lin, Xia; Wang, Zhaomin
Year: 2018
Formatted Citation: Lin, X., and Z. Wang, 2018: Simulated impact of Southern Hemisphere westerlies on Antarctic Shelf Bottom Water temperature. Advances in Polar Science, 29(3), 3-19, doi:10.13679/j.advps.2018.3.00003
Abstract: The Southern Hemisphere (SH) westerly winds have intensified and shifted poleward since the 1970s and this trend is projected to sustain under future anthropogenic forcing. The influences of intensified SH westerlies on the Antarctic coastal waters are still not clear. The variability of Antarctic Continental Shelf Bottom Water (ASBW) temperature is crucial for ice shelf basal melting and hence ice shelf mass balance in Antarctica. In order to understand the impacts of SH westerlies on the variability of ASBW temperature, atmospheric forcing in 1992 with weak westerlies and in 1998 with strong westerlies are used to drive a high-resolution ocean-sea ice general circulation model, MITgcm-ECCO2. Our simulated results show that under the atmospheric forcing in 1998, the ASBW becomes warmer in most regions around Antarctica except the coastal region between 60°-150°W, than for the case under atmospheric forcing in 1992. The warming of ASBW around Antarctica is due to the intense shoaling and warming of CDW induced by enhanced Ekman pumping as well as strengthened subpolar gyres. The strengthened subpolar gyres favor the transportation of warm water to the coast of Antarctica. The cooling of ASBW along the coast of the western Antarctic Peninsula is caused by stronger coastal currents, which bring colder water downstream from the northwest flank of the Weddell Sea.
Keywords: Antarctic Shelf Bottom Water temperature, MITgcm-ECCO2, Southern Hemisphere westerlies
Other URLs: http://www.aps-polar.org/paper/pdffulldown/A181023000001
Strobach, Ehud; Molod, Andrea; Forget, Gael; Campin, Jean-Michel; Hill, Chris; Menemenlis, Dimitris; Heimbach, Patrick (2018). Consequences of different air-sea feedbacks on ocean using MITgcm and MERRA-2 forcing: Implications for coupled data assimilation systems, Ocean Modelling (132), 91-111, 10.1016/j.ocemod.2018.10.006.
Title: Consequences of different air-sea feedbacks on ocean using MITgcm and MERRA-2 forcing: Implications for coupled data assimilation systems
Type: Journal Article
Publication: Ocean Modelling
Author(s): Strobach, Ehud; Molod, Andrea; Forget, Gael; Campin, Jean-Michel; Hill, Chris; Menemenlis, Dimitris; Heimbach, Patrick
Year: 2018
Formatted Citation: Strobach, E., A. Molod, G. Forget, J. Campin, C. Hill, D. Menemenlis, and P. Heimbach, 2018: Consequences of different air-sea feedbacks on ocean using MITgcm and MERRA-2 forcing: Implications for coupled data assimilation systems. Ocean Modelling, 132, 91-111, doi:10.1016/j.ocemod.2018.10.006
Le Fouest, Vincent; Matsuoka, Atsushi; Manizza, Manfredi; Shernetsky, Mona; Tremblay, Bruno; Babin, Marcel (2018). Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling, Biogeosciences, 5 (15), 1335-1346, 10.5194/bg-15-1335-2018.
Title: Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling
Formatted Citation: Le Fouest, V., A. Matsuoka, M. Manizza, M. Shernetsky, B. Tremblay, and M. Babin, 2018: Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling. Biogeosciences, 15(5), 1335-1346, doi:10.5194/bg-15-1335-2018
Abstract: Future climate warming of the Arctic could potentially enhance the load of terrigenous dissolved organic carbon (tDOC) of Arctic rivers due to increased carbon mobilization within watersheds. A greater flux of tDOC might impact the biogeochemical processes of the coastal Arctic Ocean (AO) and ultimately its capacity to absorb atmospheric CO2. In this study, we show that sea-surface tDOC concentrations simulated by a physical-biogeochemical coupled model in the Canadian Beaufort Sea for 2003-2011 compare favorably with estimates retrieved by satellite imagery. Our results suggest that, over spring-summer, tDOC of riverine origin contributes to 35% of primary production and that an equivalent of ∼10% of tDOC is exported westwards with the potential of fueling the biological production of the eastern Alaskan nearshore waters. The combination of model and satellite data provides promising results to extend this work to the entire AO so as to quantify, in conjunction with in situ data, the expected changes in tDOC fluxes and their potential impact on the AO biogeochemistry at basin scale.
Title: Abrupt Transitions in Submesoscale Structure in Southern Drake Passage: Glider Observations and Model Results
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Viglione, Giuliana A.; Thompson, Andrew F.; Flexas, M. Mar; Sprintall, Janet; Swart, Sebastiaan
Year: 2018
Formatted Citation: Viglione, G. A., A. F. Thompson, M. M. Flexas, J. Sprintall, and S. Swart, 2018: Abrupt Transitions in Submesoscale Structure in Southern Drake Passage: Glider Observations and Model Results. Journal of Physical Oceanography, 48(9), 2011-2027, doi:10.1175/JPO-D-17-0192.1
Cole, Sylvia T. (2018). Investigating small-scale processes from an abundance of autonomous observations, ALPS II - Autonomous Lagrangian Platforms and Sensors. A Report of the ALPS II Workshop, 25-27.
Title: Investigating small-scale processes from an abundance of autonomous observations
Type: Report
Publication: ALPS II - Autonomous Lagrangian Platforms and Sensors. A Report of the ALPS II Workshop
Author(s): Cole, Sylvia T.
Year: 2018
Formatted Citation: Cole, S. T., 2018: Investigating small-scale processes from an abundance of autonomous observations. ALPS II - Autonomous Lagrangian Platforms and Sensors. A Report of the ALPS II Workshop, La Jolla, CA, 25-27 pp.
Abstract: Small-scale processes, those with spatial and/or temporal scales less than a few hundred kilometers and a few weeks, vary on global and decadal scales. Such large-scale variations in small- scale processes have been difficult to observe. Within the last decade, global and regional-scale autonomous observations have begun to fill this observational gap. The specific processes that can be investigated from autonomous platforms are deter- mined by the minimum scale in space and time sampled by each platform. Recent examples are highlighted, and the future potential is discussed.
Bondzio, Johannes H.; Morlighem, Mathieu; Seroussi, Hélène; Wood, Michael H.; Mouginot, Jérémie (2018). Control of Ocean Temperature on Jakobshavn Isbrae’s Present and Future Mass Loss, Geophysical Research Letters, 23 (45), 12,912-12,921, 10.1029/2018GL079827.
Title: Control of Ocean Temperature on Jakobshavn Isbrae’s Present and Future Mass Loss
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Bondzio, Johannes H.; Morlighem, Mathieu; Seroussi, Hélène; Wood, Michael H.; Mouginot, Jérémie
Year: 2018
Formatted Citation: Bondzio, J. H., M. Morlighem, H. Seroussi, M. H. Wood, and J. Mouginot, 2018: Control of Ocean Temperature on Jakobshavn Isbrae's Present and Future Mass Loss. Geophys. Res. Lett., 45(23), 12,912-12,921, doi:10.1029/2018GL079827
Dushaw, Brian D. (2018). Ocean Acoustic Tomography in the North Atlantic, Journal of Atmospheric and Oceanic Technology, JTECH-D-18-0082.1, 10.1175/JTECH-D-18-0082.1.
Title: Ocean Acoustic Tomography in the North Atlantic
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Dushaw, Brian D.
Year: 2018
Formatted Citation: Dushaw, B. D., 2018: Ocean Acoustic Tomography in the North Atlantic. Journal of Atmospheric and Oceanic Technology, JTECH-D-18-0082.1, doi:10.1175/JTECH-D-18-0082.1
Smith, Timothy; Heimbach, Patrick (2018). Atmospheric origins of variability in the South Atlantic meridional overturning circulation, Journal of Climate, JCLI-D-18-0311.1, 10.1175/JCLI-D-18-0311.1.
Title: Atmospheric origins of variability in the South Atlantic meridional overturning circulation
Type: Journal Article
Publication: Journal of Climate
Author(s): Smith, Timothy; Heimbach, Patrick
Year: 2018
Formatted Citation: Smith, T., and P. Heimbach, 2018: Atmospheric origins of variability in the South Atlantic meridional overturning circulation. J. Clim., JCLI-D-18-0311.1, doi:10.1175/JCLI-D-18-0311.1
Title: Estimates of Vertical Velocity Errors for IGS ITRF2014 Stations by Applying the Improved Singular Spectrum Analysis Method and Environmental Loading Models
Formatted Citation: Klos, A., M. Gruszczynska, M. S. Bos, J. Boy, and J. Bogusz, 2018: Estimates of Vertical Velocity Errors for IGS ITRF2014 Stations by Applying the Improved Singular Spectrum Analysis Method and Environmental Loading Models. Pure and Applied Geophysics, 175(5), 1823-1840, doi:10.1007/s00024-017-1494-1
Naughten, Kaitlin A.; Meissner, Katrin J.; Galton-Fenzi, Benjamin K.; England, Matthew H.; Timmermann, Ralph; Hellmer, Hartmut H.; Hattermann, Tore; Debernard, Jens B. (2018). Intercomparison of Antarctic ice-shelf, ocean, and sea-ice interactions simulated by MetROMS-iceshelf and FESOM 1.4, Geoscientific Model Development, 4 (11), 1257-1292, 10.5194/gmd-11-1257-2018.
Title: Intercomparison of Antarctic ice-shelf, ocean, and sea-ice interactions simulated by MetROMS-iceshelf and FESOM 1.4
Type: Journal Article
Publication: Geoscientific Model Development
Author(s): Naughten, Kaitlin A.; Meissner, Katrin J.; Galton-Fenzi, Benjamin K.; England, Matthew H.; Timmermann, Ralph; Hellmer, Hartmut H.; Hattermann, Tore; Debernard, Jens B.
Year: 2018
Formatted Citation: Naughten, K. A., K. J. Meissner, B. K. Galton-Fenzi, M. H. England, R. Timmermann, H. H. Hellmer, T. Hattermann, and J. B. Debernard, 2018: Intercomparison of Antarctic ice-shelf, ocean, and sea-ice interactions simulated by MetROMS-iceshelf and FESOM 1.4. Geoscientific Model Development, 11(4), 1257-1292, doi:10.5194/gmd-11-1257-2018
Abstract: An increasing number of Southern Ocean models now include Antarctic ice-shelf cavities, and simulate thermodynamics at the ice-shelf/ocean interface. This adds another level of complexity to Southern Ocean simulations, as ice shelves interact directly with the ocean and indirectly with sea ice. Here, we present the first model intercomparison and evaluation of present-day ocean/sea-ice/ice-shelf interactions, as simulated by two models: a circumpolar Antarctic configuration of MetROMS (ROMS: Regional Ocean Modelling System coupled to CICE: Community Ice CodE) and the global model FESOM (Finite Element Sea-ice Ocean Model), where the latter is run at two different levels of horizontal resolution. From a circumpolar Antarctic perspective, we compare and evaluate simulated ice-shelf basal melting and sub-ice-shelf circulation, as well as sea-ice properties and Southern Ocean water mass characteristics as they influence the sub-ice-shelf processes. Despite their differing numerical methods, the two models produce broadly similar results and share similar biases in many cases. Both models reproduce many key features of observations but struggle to reproduce others, such as the high melt rates observed in the small warm-cavity ice shelves of the Amundsen and Bellingshausen seas. Several differences in model design show a particular influence on the simulations. For example, FESOM's greater topographic smoothing can alter the geometry of some ice-shelf cavities enough to affect their melt rates; this improves at higher resolution, since less smoothing is required. In the interior Southern Ocean, the vertical coordinate system affects the degree of water mass erosion due to spurious diapycnal mixing, with MetROMS' terrain-following coordinate leading to more erosion than FESOM's z coordinate. Finally, increased horizontal resolution in FESOM leads to higher basal melt rates for small ice shelves, through a combination of stronger circulation and small-scale intrusions of warm water from offshore.
Wunsch, Carl; Ferrari, Raffaele (2018). 100 Years of the Ocean General Circulation, Meteorological Monographs (59), 7.1-7.32, 10.1175/AMSMONOGRAPHS-D-18-0002.1.
Formatted Citation: Wunsch, C., and R. Ferrari, 2018: 100 Years of the Ocean General Circulation. Meteorological Monographs, 59, 7.1-7.32, doi:10.1175/AMSMONOGRAPHS-D-18-0002.1
Morlighem, Mathieu; Wood, Michael; Seroussi, Hélène; Choi, Youngmin; Rignot, Eric (2018). Modeling the response of Northwest Greenland to enhanced ocean thermal forcing and subglacial discharge, The Cryosphere Discussions, 1-18, 10.5194/tc-2018-214.
Formatted Citation: Morlighem, M., M. Wood, H. Seroussi, Y. Choi, and E. Rignot, 2018: Modeling the response of Northwest Greenland to enhanced ocean thermal forcing and subglacial discharge. The Cryosphere Discussions, 1-18, doi:10.5194/tc-2018-214
Abstract: Calving front dynamics is an important control on Greenland's ice mass balance. Ice front retreat of marine-terminating glaciers may, for example, lead to a loss in resistive stress, which ultimately results in glacier acceleration and thinning. Over the past decade, it has been suggested that such retreats may be triggered by warm and salty Atlantic water, which is typically found at a depth below 200–300m. An increase in subglacial water discharge at glacier ice fronts due to enhanced surface runoff may also be responsible for an intensification of undercutting and calving. An increase in ocean thermal forcing or subglacial discharge therefore has the potential to destabilize marine terminating glaciers along the coast of Greenland. It remains unclear which glaciers are currently stable but may retreat in the future, and how far inland and how fast they will retreat. Here, we quantify the sensitivity and vulnerability of marine-terminating glaciers along the Northwest coast of Greenland (from 72.5º to 76ºN) to the ocean forcing and subglacial discharge using the Ice Sheet System Model (ISSM). We rely on the undercutting parameterization based on ocean thermal forcing and subglacial discharge, and use ocean temperature and salinity from high-resolution ECCO2 (Estimating the Circulation & Climate of the Ocean, Phase II) simulations at the fjords mouth to constrain the ocean thermal forcing. The ice flow model includes a calving law based on a tensile Von Mises criterion. While these parameterizations remain approximations and do not include all the physical processes at play, they have been shown to provide reliable estimates of undercutting and calving rates, respectively, on a number of glaciers along the coast of Greenland. We find that some glaciers, such as Dietrichson Gletscher or Alison Gletscher, are sensitive to small increases in ocean thermal forcing, while others, such as Illullip Sermia or Cornell Gletscher, are remarkably stable and remain stable, even in a 3-degree ocean warming scenario. Under the most intense experiment, we find that Hayes Gletscher retreats by more than 50km inland into a deep trough and its velocity increases by a factor of 10 over only 15 years. The model confirms that ice-ocean interactions can trigger extensive and rapid glacier retreat, but the bed controls the rate and magnitude of the retreat. Under current oceanic and atmospheric condition, we find that this sector alone will contribute more than 1cm to sea level, and up to 3cm under the most extreme scenario.
Van der Stocken, Tom; Carroll, Dustin; Menemenlis, Dimitris; Simard, Marc; Koedam, Nico (2018). Global-scale dispersal and connectivity in mangroves, Proceedings of the National Academy of Sciences, 201812470, 10.1073/pnas.1812470116.
Title: Global-scale dispersal and connectivity in mangroves
Type: Journal Article
Publication: Proceedings of the National Academy of Sciences
Author(s): Van der Stocken, Tom; Carroll, Dustin; Menemenlis, Dimitris; Simard, Marc; Koedam, Nico
Year: 2018
Formatted Citation: Van der Stocken, T., D. Carroll, D. Menemenlis, M. Simard, and N. Koedam, 2018: Global-scale dispersal and connectivity in mangroves. Proceedings of the National Academy of Sciences, 201812470, doi:10.1073/pnas.1812470116
Abstract: Dispersal provides a key mechanism for geographical range shifts in response to changing environmental conditions. For mangroves, which are highly susceptible to climate change, the spatial scale of dispersal remains largely unknown. Here we use a high-resolution, eddy- and tide-resolving numerical ocean model to simulate mangrove propagule dispersal across the global ocean and generate connectivity matrices between mangrove habitats using a range of floating periods. We find high rates of along-coast transport and transoceanic dispersal across the Atlantic, Pacific, and Indian Oceans. No connectivity is observed between populations on either side of the American and African continents. Archipelagos, such as the Galapagos and those found in Polynesia, Micronesia, and Melanesia, act as critical stepping-stones for dispersal across the Pacific Ocean. Direct and reciprocal dispersal routes across the Indian Ocean via the South Equatorial Current and seasonally reversing monsoon currents, respectively, allow connectivity between western Indian Ocean and Indo-West Pacific sites. We demonstrate the isolation of the Hawaii Islands and help explain the presence of mangroves on the latitudinal outlier Bermuda. Finally, we find that dispersal distance and connectivity are highly sensitive to the minimum and maximum floating periods. We anticipate that our findings will guide future research agendas to quantify biophysical factors that determine mangrove dispersal and connectivity, including the influence of ocean surface water properties on metabolic processes and buoyancy behavior, which may determine the potential of viably reaching a suitable habitat. Ultimately, this will lead to a better understanding of global mangrove species distributions and their response to changing climate conditions.
Formatted Citation: Yu, N., J. Li, J. Ray, and W. Chen, 2018: Improved geophysical excitation of length-of-day constrained by Earth orientation parameters and satellite gravimetry products. Geophysical Journal International, 214(3), 1633-1651, doi:10.1093/gji/ggy204
Abstract: At timescales shorter than about 2 yr, non-tidal length-of-day (LOD) variations are mainly excited by angular momentum exchanges between the atmospheric, oceanic and continental hydrological fluid envelopes and the underlying solid Earth. But, neither agreement among different geophysical models for the fluid dynamics nor consistency with geodetic observations of LOD has reached satisfactory levels. This is mainly ascribed to significant discrepancies and uncertainties in the theories and assumptions adopted by different modelling groups, in their numerical methods, and in the accuracy and coverage of global input data fields. Based on careful comparisons with more accurate geodetic measurements and satellite gravimetry products (from satellite laser ranging, SLR), observed LOD and C20 geopotential time-series can provide strong constraints to evaluate or form combined geophysical models. In this study, wavelet decomposition is used to extract several narrow-band components to compare in addition to considering the total signals. We then make refinements to the least difference combination (LDC) method proposed by Chen et al., to form multimodel geophysical excitations. Two combination variants, called the weighted mean combination (WMC2 and WMC4), are also evaluated. All the multimodel methods attempt to extract the best-modelled frequency components from each geophysical model by relying on geodetic excitation and the C20 series as references. The comparative performances of the three combinations LDC, WMC2 and WMC4 and the original single models are determined. We find that (1) Estimating the Circulation and Climate of the Ocean and Max-Planck-Institute for Meteorology Ocean Model give a more reliable view of the ocean redistributions than the Ocean Model for Circulation and Tides used by European Centre for Medium-Range Weather Forecasts, especially for the annual component; (2) C20 series from SLR can provide a rigorous constraint for the total matter excitation of the geophysical fluids, especially for broad-band parts; (3) the Sea-Level Angular Momentum functions term, correcting for sea-level effects (global mass balance) put forward by the Earth System Modelling group at GFZ German Research Centre for Geosciences, can significantly improve the Hydrospheric Effective Angular Momentum functions matter terms; (4) the LDC/WMC combinations are much better than the original individual geophysical model excitations, reducing the magnitude of unexplained LOD excitations to roughly the 10 μs level; (5) the level of residual LOD variations after removing models or model combinations is remarkably invariant with respect to LOD periods between ∼2 months and ∼3 yr, being 12-14 μs for the best original models and 7-12 μs for our combinations; (6) while differences between the IERS 14C04 and the JPL SPACE2015 geodetic LOD time-series are not negligible, errors in both series are still not large compared to the geophysical models (for periods >2 months) so the impact on excitation studies is minimal except at semiannual periods and usually 14C04 compares better with excitation models. The improved geophysical models are recommended to replace the original ones as they present overwhelming advantages.
Wińska, Małgorzata; Śliwińska, Justyna (2018). Assessing hydrological signal in polar motion from observations and geophysical models, Studia Geophysica et Geodaetica, 2019 (63), 10.1007/s11200-018-1028-z.
Title: Assessing hydrological signal in polar motion from observations and geophysical models
Type: Journal Article
Publication: Studia Geophysica et Geodaetica
Author(s): Wińska, Małgorzata; Śliwińska, Justyna
Year: 2018
Formatted Citation: Wińska, M., and J. Śliwińska, 2018: Assessing hydrological signal in polar motion from observations and geophysical models. Studia Geophysica et Geodaetica, 63(2019), doi:10.1007/s11200-018-1028-z
Abstract: Changes in Terrestrial Water Storage (TWS) due to seasonal changes in soil moisture, ice and snow loading and melting influence the Earth's inertia tensor. Quantitative assessment of hydrological effects of polar motion remains unclear because of the lack of the observations and differences between various atmospheric and ocean models. We compare the effects of several hydrological excitation functions computed as the difference between the excitation function of polar motion Geodetic Angular Momentum (GAM) and joint atmospheric plus oceanic excitation functions, called geodetic residuals. Geodetic residuals are computed for different Atmospheric Angular Momentum (AAM) and Oceanic Angular Momentum (OAM) models and are analyzed and compared with the hydrological excitation function determined from the Land Surface Discharge Model. They are analyzed on decadal, interannual, seasonal and non-seasonal time scales. The equatorial components of hydrological geodetic excitation functions χ1 and χ2 are decomposed into prograde and retrograde time series by applying Complex Fourier Transform Models. The agreement between hydrological geodetic residuals and excitation functions is validated using Taylor diagrams. This shows that agreement is highly dependent on AAM and OAM models. Errors in these models affect the resulting geodetic residuals and have a strong impact on the Earth's angular momentum budget.
Bashmachnikov, I. L.; Yurova, A. Yu.; Bobylev, L. P.; Vesman, A. V. (2018). Seasonal and Interannual Variations of Heat Fluxes in the Barents Sea Region, Izvestiya, Atmospheric and Oceanic Physics, 2 (54), 213-222, 10.1134/S0001433818020032.
Title: Seasonal and Interannual Variations of Heat Fluxes in the Barents Sea Region
Type: Journal Article
Publication: Izvestiya, Atmospheric and Oceanic Physics
Author(s): Bashmachnikov, I. L.; Yurova, A. Yu.; Bobylev, L. P.; Vesman, A. V.
Year: 2018
Formatted Citation: Bashmachnikov, I. L., A. Y. Yurova, L. P. Bobylev, and A. V. Vesman, 2018: Seasonal and Interannual Variations of Heat Fluxes in the Barents Sea Region. Izvestiya, Atmospheric and Oceanic Physics, 54(2), 213-222, doi:10.1134/S0001433818020032
Keywords: and the atmosphere, barents sea, bjerknes compensation mechanism, coupled, cycles in the ocean, fluxes, mit eddy-permitting ocean model, oceanic and atmospheric heat, singular spec-, wavelet analysis
Liang, Xi; Losch, Martin (2018). On the effects of increased vertical mixing on the Arctic Ocean and sea ice, Journal of Geophysical Research: Oceans, April 2007 (2007), 1-17, 10.1029/2018JC014303.
Title: On the effects of increased vertical mixing on the Arctic Ocean and sea ice
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Liang, Xi; Losch, Martin
Year: 2018
Formatted Citation: Liang, X., and M. Losch, 2018: On the effects of increased vertical mixing on the Arctic Ocean and sea ice. J. Geophys. Res. Ocean., 2007(April 2007), 1-17, doi:10.1029/2018JC014303
Bigdeli, A.; Hara, T.; Loose, B.; Nguyen, A. T. (2018). Wave Attenuation and Gas Exchange Velocity in Marginal Sea Ice Zone, Journal of Geophysical Research: Oceans, 3 (123), 2293-2304, 10.1002/2017JC013380.
Title: Wave Attenuation and Gas Exchange Velocity in Marginal Sea Ice Zone
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Bigdeli, A.; Hara, T.; Loose, B.; Nguyen, A. T.
Year: 2018
Formatted Citation: Bigdeli, A., T. Hara, B. Loose, and A. T. Nguyen, 2018: Wave Attenuation and Gas Exchange Velocity in Marginal Sea Ice Zone. J. Geophys. Res. Ocean., 123(3), 2293-2304, doi:10.1002/2017JC013380
Castellani, Giulia; Losch, Martin; Ungermann, Mischa; Gerdes, Rüdiger (2018). Sea-ice drag as a function of deformation and ice cover: Effects on simulated sea ice and ocean circulation in the Arctic, Ocean Modelling (128), 48-66, 10.1016/j.ocemod.2018.06.002.
Formatted Citation: Castellani, G., M. Losch, M. Ungermann, and R. Gerdes, 2018: Sea-ice drag as a function of deformation and ice cover: Effects on simulated sea ice and ocean circulation in the Arctic. Ocean Modelling, 128, 48-66, doi:10.1016/j.ocemod.2018.06.002
Dwivedi, Suneet; Srivastava, Atul; Mishra, Alok Kumar (2018). Upper Ocean Four-Dimensional Variational Data Assimilation in the Arabian Sea and Bay of Bengal, Marine Geodesy, 3 (41), 230-257, 10.1080/01490419.2017.1405128.
Formatted Citation: Dwivedi, S., A. Srivastava, and A. K. Mishra, 2018: Upper Ocean Four-Dimensional Variational Data Assimilation in the Arabian Sea and Bay of Bengal. Marine Geodesy, 41(3), 230-257, doi:10.1080/01490419.2017.1405128
Formatted Citation: Ferster, B. S., B. Subrahmanyam, I. Fukumori, and E. S. Nyadjro, 2018: Variability of Southern Ocean Transports. Journal of Physical Oceanography, 48(11), 2667-2688, doi:10.1175/JPO-D-18-0055.1
Śliwińska, Justyna; Wińska, Małgorzata; Nastula, Jolanta (2018). Terrestrial water storage variations and their effect on polar motion, Acta Geophysica, 10.1007/s11600-018-0227-x.
Formatted Citation: Śliwińska, J., M. Wińska, and J. Nastula, 2018: Terrestrial water storage variations and their effect on polar motion. Acta Geophysica, doi:10.1007/s11600-018-0227-x
Lamona, Bernawis; Hauck, Judith; Völker, Christoph (2018). Evaluation of a global ocean general circulation model; The Lat-Lon-Cap (LLC90) configuration of the MITgcm, IOP Conference Series: Earth and Environmental Science (162), 012002, 10.1088/1755-1315/162/1/012002.
Title: Evaluation of a global ocean general circulation model; The Lat-Lon-Cap (LLC90) configuration of the MITgcm
Type: Journal Article
Publication: IOP Conference Series: Earth and Environmental Science
Author(s): Lamona, Bernawis; Hauck, Judith; Völker, Christoph
Year: 2018
Formatted Citation: Lamona, B., J. Hauck, and C. Völker, 2018: Evaluation of a global ocean general circulation model; The Lat-Lon-Cap (LLC90) configuration of the MITgcm. IOP Conference Series: Earth and Environmental Science, 162, 012002, doi:10.1088/1755-1315/162/1/012002
Formatted Citation: Uotila, P. and Coauthors, 2018: An assessment of ten ocean reanalyses in the polar regions. Climate Dynamics, doi:10.1007/s00382-018-4242-z
Volkov, Denis L.; Baringer, Molly; Smeed, David; Johns, William; Landerer, Felix W. (2018). Teleconnection between the Atlantic Meridional Overturning Circulation and sea level in the Mediterranean Sea, Journal of Climate, JCLI-D-18-0474.1, 10.1175/JCLI-D-18-0474.1.
Title: Teleconnection between the Atlantic Meridional Overturning Circulation and sea level in the Mediterranean Sea
Type: Journal Article
Publication: Journal of Climate
Author(s): Volkov, Denis L.; Baringer, Molly; Smeed, David; Johns, William; Landerer, Felix W.
Year: 2018
Formatted Citation: Volkov, D. L., M. Baringer, D. Smeed, W. Johns, and F. W. Landerer, 2018: Teleconnection between the Atlantic Meridional Overturning Circulation and sea level in the Mediterranean Sea. J. Clim., JCLI-D-18-0474.1, doi:10.1175/JCLI-D-18-0474.1
Choi, Youngmin; Morlighem, Mathieu; Wood, Michael; Bondzio, Johannes H. (2018). Comparison of four calving laws to model Greenland outlet glaciers, The Cryosphere, 12 (12), 3735-3746, 10.5194/tc-12-3735-2018.
Title: Comparison of four calving laws to model Greenland outlet glaciers
Type: Journal Article
Publication: The Cryosphere
Author(s): Choi, Youngmin; Morlighem, Mathieu; Wood, Michael; Bondzio, Johannes H.
Year: 2018
Formatted Citation: Choi, Y., M. Morlighem, M. Wood, and J. H. Bondzio, 2018: Comparison of four calving laws to model Greenland outlet glaciers. Cryosph., 12(12), 3735-3746, doi:10.5194/tc-12-3735-2018
Abstract: Calving is an important mechanism that controls the dynamics of marine terminating glaciers of Greenland. Iceberg calving at the terminus affects the entire stress regime of outlet glaciers, which may lead to further retreat and ice flow acceleration. It is therefore critical to accurately parameterize calving in ice sheet models in order to improve the projections of ice sheet change over the coming decades and reduce the uncertainty in their contribution to sea-level rise. Several calving laws have been proposed, but most of them have been applied only to a specific region and have not been tested on other glaciers, while some others have only been implemented in 1-D flowline or vertical flowband models. Here, we test and compare several calving laws recently proposed in the literature using the Ice Sheet System Model (ISSM). We test these calving laws on nine tidewater glaciers of Greenland. We compare the modeled ice front evolution to the observed retreat from Landsat data collected over the past 10 years, and assess which calving law has better predictive abilities for each glacier. Overall, the von Mises tensile stress calving law is more satisfactory than other laws for simulating observed ice front retreat, but new parameterizations that better capture the different modes of calving should be developed. Although the final positions of ice fronts are different for forecast simulations with different calving laws, our results confirm that ice front retreat highly depends on bed topography, irrespective of the calving law employed. This study also confirms that calving dynamics needs to be 3-D or in plan view in ice sheet models to account for complex bed topography and narrow fjords along the coast of Greenland. ]]>
Pillar, Helen R; Johnson, Helen L; Marshall, David P; Heimbach, Patrick; Takao, So (2018). Impacts of Atmospheric Reanalysis Uncertainty on Atlantic Overturning Estimates at 25°N, Journal of Climate, 21 (31), 8719-8744, 10.1175/JCLI-D-18-0241.1.
Title: Impacts of Atmospheric Reanalysis Uncertainty on Atlantic Overturning Estimates at 25°N
Type: Journal Article
Publication: Journal of Climate
Author(s): Pillar, Helen R; Johnson, Helen L; Marshall, David P; Heimbach, Patrick; Takao, So
Year: 2018
Formatted Citation: Pillar, H. R., H. L. Johnson, D. P. Marshall, P. Heimbach, and S. Takao, 2018: Impacts of Atmospheric Reanalysis Uncertainty on Atlantic Overturning Estimates at 25°N. J. Clim., 31(21), 8719-8744, doi:10.1175/JCLI-D-18-0241.1
Abstract: Atmospheric reanalyses are commonly used to force numerical ocean models, but despite large discrepancies reported between different products, the impact of reanalysis uncertainty on the simulated ocean state is rarely assessed. In this study, the impact of uncertainty in surface fluxes of buoyancy and momentum on the modeled Atlantic meridional overturning at 25°N is quantified for the period January 1994?December 2011. By using an ocean-only climate model and its adjoint, the space and time origins of overturning uncertainty resulting from air?sea flux uncertainty are fully explored. Uncertainty in overturning induced by prior air?sea flux uncertainty can exceed 4 Sv (where 1 Sv ≡ 106 m3 s?1) within 15 yr, at times exceeding the amplitude of the ensemble-mean overturning anomaly. A key result is that, on average, uncertainty in the overturning at 25°N is dominated by uncertainty in the zonal wind at lags of up to 6.5 yr and by uncertainty in surface heat fluxes thereafter, with winter heat flux uncertainty over the Labrador Sea appearing to play a critically important role.
Evans, Dafydd Gwyn; Zika, Jan D; Naveira Garabato, Alberto C; Nurser, A J George (2018). The Cold Transit of Southern Ocean Upwelling, Geophysical Research Letters, 24 (45), 13,313-386,395, 10.1029/2018GL079986.
Title: The Cold Transit of Southern Ocean Upwelling
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Evans, Dafydd Gwyn; Zika, Jan D; Naveira Garabato, Alberto C; Nurser, A J George
Year: 2018
Formatted Citation: Evans, D. G., J. D. Zika, A. C. Naveira Garabato, and A. J. G. Nurser, 2018: The Cold Transit of Southern Ocean Upwelling. Geophys. Res. Lett., 45(24), 13,313-386,395, doi:10.1029/2018GL079986
Abstract: The upwelling of deep waters in the Southern Ocean is a critical component of the climate system. The time and zonal mean dynamics of this circulation describe the upwelling of Circumpolar Deep Water and the downwelling of Antarctic Intermediate Water. The thermodynamic drivers of the circulation and their seasonal cycle play a potentially key regulatory role. Here an observationally constrained ocean model and an observation-based seasonal climatology are analyzed from a thermodynamic perspective, to assess the diabatic processes controlling overturning in the Southern Ocean. This reveals a seasonal two-stage cold transit in the formation of intermediate water from upwelled deep water. First, relatively warm and saline deep water is transformed into colder and fresher near-surface winter water via wintertime mixing. Second, winter water warms to form intermediate water through summertime surface heat fluxes. The mixing-driven pathway from deep water to winter water follows mixing lines in thermohaline coordinates indicative of nonlinear processes.
Swart, S; Johnson, K; Mazloff, M R; Meijers, A; Meredith, M P; Newman, L; Sallée, Jean-Baptiste (2018). Southern Ocean in State of the Climate in 2017, Bull. Amer. Meteor. Soc. (99).
Title: Southern Ocean in State of the Climate in 2017
Type: Journal Article
Publication: Bull. Amer. Meteor. Soc.
Author(s): Swart, S; Johnson, K; Mazloff, M R; Meijers, A; Meredith, M P; Newman, L; Sallée, Jean-Baptiste
Year: 2018
Formatted Citation: Swart, S., K. Johnson, M. R. Mazloff, A. Meijers, M. P. Meredith, L. Newman, and J. Sallée, 2018: Southern Ocean in State of the Climate in 2017. Bull. Amer. Meteor. Soc., 99
Abstract:
Keywords:
ECCO Products Used: SOSE
URL:
Other URLs:
Tamsitt, V; Abernathey, R P; Mazloff, M R; Wang, J; Talley, L D (2018). Transformation of Deep Water Masses Along Lagrangian Upwelling Pathways in the Southern Ocean, Journal of Geophysical Research: Oceans, 10.1002/2017JC013409.
Title: Transformation of Deep Water Masses Along Lagrangian Upwelling Pathways in the Southern Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Tamsitt, V; Abernathey, R P; Mazloff, M R; Wang, J; Talley, L D
Year: 2018
Formatted Citation: Tamsitt, V., R. P. Abernathey, M. R. Mazloff, J. Wang, and L. D. Talley, 2018: Transformation of Deep Water Masses Along Lagrangian Upwelling Pathways in the Southern Ocean. J. Geophys. Res. Ocean., doi:10.1002/2017JC013409
Abstract: n/a
Keywords: Southern Ocean, Topographic/bathymetric interactions, Upwelling and convergences, and mixing processes, diffusion, lagrangian, mixing, numerical modeling, topography, turbulence, upwelling, water mass transformation, water masses
Title: Evidence of jet-scale overturning ocean circulations in Argo float trajectories
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Li, Q; Lee, S; Mazloff, M
Year: 2018
Formatted Citation: Li, Q., S. Lee, and M. Mazloff, 2018: Evidence of jet-scale overturning ocean circulations in Argo float trajectories. Geophys. Res. Lett., 45(21), 11866-11874, doi:10.1029/2018gl078950
Abstract: In a recent study, it was proposed that Reynolds stress by oceanic mesoscale eddies not only drives jets such as Subantarctic Front but also can force overturning circulations that are composed of rising motion on the poleward flank and sinking motion on the equatorward flank of the jets. In that study, the thermally indirect, jet-scale overturning circulations (JSOCs) were detected in an eddy-resolving model simulation of the Southern Ocean. Here observational evidence of the existence of JSOCs is demonstrated by showing that the Argo floats tend to drift poleward across the jet with the maximum drift speed coinciding with the corresponding jet maximum. This finding has an implication for the observed deep mixed layer because it was previously shown that in the model the JSOCs play a key role in preconditioning the formation of a deep and narrow mixed layer at just similar to 1 degrees north of the Subantarctic Front. Plain Language Summary In the Southern Ocean, some of the deepest mixed layers from early to late winter have a meridional scale of only similar to 2 degrees and a depth of over 500 m. These mixed layers are thought to be a critical pathway for ocean ventilation of greenhouse gases and heat and thus considered as an important regulator of climate. Yet the mechanism for the key observed features of deep mixed layers is not well understood and is a subject of active research. This paper demonstrates observational evidence of an overturning circulation, which was theorized to exist and to help account for the observed feature of the deep mixed layer. Numerous efforts to understand the mechanism of the deep mixed layer are underway. Therefore, it is important to present this newly identified overturning circulation to the community in a timely manner.
Masich, Jessica; Mazloff, Matthew R; Chereskin, Teresa K (2018). Interfacial Form Stress in the Southern Ocean State Estimate, Journal of Geophysical Research: Oceans, 5 (123), 3368-3385, 10.1029/2018JC013844.
Title: Interfacial Form Stress in the Southern Ocean State Estimate
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Masich, Jessica; Mazloff, Matthew R; Chereskin, Teresa K
Year: 2018
Formatted Citation: Masich, J., M. R. Mazloff, and T. K. Chereskin, 2018: Interfacial Form Stress in the Southern Ocean State Estimate. J. Geophys. Res. Ocean., 123(5), 3368-3385, doi:10.1029/2018JC013844
Abstract: The wind stress that drives the Antarctic Circumpolar Current (ACC) exits the fluid via topographic form stress (TFS) at the sea floor; interfacial form stress (IFS) is thought to carry much of this momentum from source to sink. These form stresses combine to help set the strength and structure of the Southern Ocean meridional overturning circulation (MOC), a key nexus of heat and gas exchange between the deep ocean and the atmosphere. For the first time in a general circulation model, we calculate the time?varying, three?dimensional IFS field directly from zonal pressure gradients across vertical perturbations in isopycnal layer interfaces. We confirm previous findings that IFS compensates wind stress at the surface and topographic form stress at the seafloor in the Drake Passage latitudes. We find that zonal and time?mean IFS is primarily responsible for this surface wind stress compensation, with some contribution from transient eddy IFS. Mean, standing eddy, and transient eddy IFS combine to compensate topographic form stress at depth. Both standing and transient eddy IFS concentrate at stationary meanders along the ACC, and transient eddy IFS dominates standing eddy IFS in regions of high eddy kinetic energy. Finally, total IFS changes sign from balancing eastward wind stress to balancing westward topographic form stress around 28.1 kg m?3, close to the upper limit of Antarctic Bottom Water, indicating the role of buoyancy forcing in setting the structure of the IFS field.
Keywords: Southern Ocean, Southern Ocean state estimate, interfacial form stress, meridional overturning circulation, momentum balance, topographic form stress
Other URLs: http://doi.wiley.com/10.1029/2018JC013844
Liang, Yu-Chiao; Mazloff, Matthew R; Rosso, Isabella; Fang, Shih-Wei; Yu, Jin-Yi (2018). A Multi-variate Empirical Orthogonal Function Method to Construct Nitrate Maps in the Southern Ocean, Journal of Atmospheric and Oceanic Technology, doi.org/10.1175/JTECH-D-18-0018.1.
Formatted Citation: Liang, Y., M. R. Mazloff, I. Rosso, S. Fang, and J. Yu, 2018: A Multi-variate Empirical Orthogonal Function Method to Construct Nitrate Maps in the Southern Ocean. Journal of Atmospheric and Oceanic Technology, doi:doi.org/10.1175/JTECH-D-18-0018.1
Abstract: The ability to construct nitrate maps in the Southern Ocean (SO) from sparse observations is important for marine biogeochemistry research, as it offers a geographical estimate of biological productivity. The goal of this study is to infer the skill of constructed SO nitrate maps using varying data sampling strategies. The mapping method uses multi-variate Empirical Orthogonal Functions (MEOFs) constructed from nitrate, salinity, and potential temperature (N-S-T) fields from a biogeochemical general circulation model simulation. Synthetic N-S-T datasets are created by sampling modeled N-S-T fields in specific regions, either determined by random selection or by selecting regions over a certain threshold of nitrate temporal variances. The first five hundred MEOF modes, determined by their capability to reconstruct the original N-S-T fields, are projected onto these synthetic N-S-T data to construct time-varying nitrate maps. Normalized root-mean-square errors (NRMSEs) are calculated between the constructed nitrate maps and the original modeled fields for different sampling strategies. The sampling strategy according to nitrate variances is shown to yield maps with lower NRMSEs than mapping adopting random sampling. A K-means cluster method that considers the N-S-T combined variances to identify key regions to insert data is most effective in reducing the mapping errors. These findings are further quantified by a series of mapping error analyses that also address the significance of data sampling density. The results provide a sampling framework to prioritize the deployment of biogeochemical Argo floats for constructing nitrate maps.
Talley, L D; Rosso, I; Kamenkovich, I; Mazloff, M R; Wang, J; Boss, E; Gray, A R; Johnson, K S; Key, R; Riser, S C; Williams, N L; Sarmiento, J L (2018). Southern Ocean biogeochemical float deployment strategy, with example from the Greenwich Meridian line (GO-SHIP A12), Journal of Geophysical Research: Oceans.
Title: Southern Ocean biogeochemical float deployment strategy, with example from the Greenwich Meridian line (GO-SHIP A12)
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Talley, L D; Rosso, I; Kamenkovich, I; Mazloff, M R; Wang, J; Boss, E; Gray, A R; Johnson, K S; Key, R; Riser, S C; Williams, N L; Sarmiento, J L
Year: 2018
Formatted Citation: Talley, L. D. and Coauthors, 2018: Southern Ocean biogeochemical float deployment strategy, with example from the Greenwich Meridian line (GO-SHIP A12). J. Geophys. Res. Ocean.
Zaba, Katherine D; Rudnick, Daniel L; Cornuelle, Bruce D; Gopalakrishnan, Ganesh; Mazloff, Matthew R (2018). Annual and Interannual Variability in the California Current System: Comparison of an Ocean State Estimate with a Network of Underwater Gliders, Journal of Physical Oceanography, 12 (48), 2965-2988, 10.1175/JPO-D-18-0037.1.
Title: Annual and Interannual Variability in the California Current System: Comparison of an Ocean State Estimate with a Network of Underwater Gliders
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Zaba, Katherine D; Rudnick, Daniel L; Cornuelle, Bruce D; Gopalakrishnan, Ganesh; Mazloff, Matthew R
Year: 2018
Formatted Citation: Zaba, K. D., D. L. Rudnick, B. D. Cornuelle, G. Gopalakrishnan, and M. R. Mazloff, 2018: Annual and Interannual Variability in the California Current System: Comparison of an Ocean State Estimate with a Network of Underwater Gliders. Journal of Physical Oceanography, 48(12), 2965-2988, doi:10.1175/JPO-D-18-0037.1
Abstract: A data-constrained state estimate of the southern California Current System (CCS) is presented and compared with withheld California Cooperative Oceanic Fisheries Investigations (CalCOFI) data and assimilated glider data over 2007-17. The objective of this comparison is to assess the ability of the California State Estimate (CASE) to reproduce the key physical features of the CCS mean state, annual cycles, and interannual variability along the three sections of the California Underwater Glider Network (CUGN). The assessment focuses on several oceanic metrics deemed most important for characterizing physical variability in the CCS: 50-m potential temperature, 80-m salinity, and 26 kg m-3 isopycnal depth and salinity. In the time mean, the CASE reproduces large-scale thermohaline and circulation structures, including observed temperature gradients, shoaling isopycnals, and the locations and magnitudes of the equatorward California Current and poleward California Undercurrent. With respect to the annual cycle, the CASE captures the phase and, to a lesser extent, the magnitude of upper-ocean warming and stratification from late summer to early fall and of isopycnal heave during springtime upwelling. The CASE also realistically captures near-surface diapycnal mixing during upwelling season and the semiannual cycle of the California Undercurrent. In terms of interannual variability, the most pronounced signals are the persistent warming and downwelling anomalies of 2014-16 and a positive isopycnal salinity anomaly that peaked with the 2015-16 El Niño.
Briggs, Ellen M; Martz, Todd R; Talley, Lynne D; Mazloff, Matthew R; Johnson, Kenneth S (2018). Physical and Biological Drivers of Biogeochemical Tracers Within the Seasonal Sea Ice Zone of the Southern Ocean From Profiling Floats, Journal of Geophysical Research: Oceans, 10.1002/2017JC012846.
Title: Physical and Biological Drivers of Biogeochemical Tracers Within the Seasonal Sea Ice Zone of the Southern Ocean From Profiling Floats
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Briggs, Ellen M; Martz, Todd R; Talley, Lynne D; Mazloff, Matthew R; Johnson, Kenneth S
Year: 2018
Formatted Citation: Briggs, E. M., T. R. Martz, L. D. Talley, M. R. Mazloff, and K. S. Johnson, 2018: Physical and Biological Drivers of Biogeochemical Tracers Within the Seasonal Sea Ice Zone of the Southern Ocean From Profiling Floats. J. Geophys. Res. Ocean., doi:10.1002/2017JC012846
Giglio, D; Lyubchich, V; Mazloff, M R (2018). Estimating Oxygen in the Southern Ocean using Argo Temperature and Salinity, Journal of Geophysical Research: Oceans, doi:10.1029/2017JC013404.
Title: Estimating Oxygen in the Southern Ocean using Argo Temperature and Salinity
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Giglio, D; Lyubchich, V; Mazloff, M R
Year: 2018
Formatted Citation: Giglio, D., V. Lyubchich, and M. R. Mazloff, 2018: Estimating Oxygen in the Southern Ocean using Argo Temperature and Salinity. J. Geophys. Res. Ocean., doi:doi:10.1029/2017JC013404
Abstract: An Argo based estimate of Oxygen (O2) at 150 m is presented for the Southern Ocean (SO) from Temperature (T), Salinity (S), and O2 Argo profiles collected during 2008?2012. The method is based on a supervised machine learning algorithm known as Random Forest (RF) regression, and provides an estimate for O2 given T, S, location and time information. The method is validated by attempting to reproduce the Southern Ocean State Estimate (SOSE) O2 field using synthetic data sampled from SOSE. The RF mapping shows skill in the majority of the domain, but is problematic in eastern boundary regions. Maps of O2 at 150 m derived from observed profiles suggest that SOSE and the World Ocean Atlas 2013 climatology may overestimate annual mean O2 in the SO, both on a global and basin scale. A large regional bias is found east of Argentina, where high O2 values in the Argo based estimate are confined closer to the coast compared to other products. SOSE may also underestimate the annual cycle of O2. Evaluation of the RF based method demonstrates its potential to improve understanding of O2 annual mean fields and variability from sparse O2 measurements. This implies the algorithm will also be effective for mapping other biogeochemical variables (e.g. nutrients and carbon). Furthermore, our RF evaluation results can be used to inform the design of future enhancements to the current array of O2 profiling floats.
Keywords: Argo and BGC-Argo, Machine learning, Mapping methods, Southern Ocean, Southern Ocean State Estimate (SOSE), oxygen
Formatted Citation: Chamberlain, P., L. D. Talley, M. Mazloff, S. Riser, K. Speer, A. R. Gray, and A. Schwartzman, 2018: Observing the ice-covered Weddell Gyre with profiling floats: position uncertainties and correlation statistics. J. Geophys. Res. Ocean.(ja), doi:10.1029/2017JC012990
Abstract: Argo-type profiling floats do not receive satellite positioning while under sea ice. Common practice is to approximate unknown positions by linearly interpolating latitude-longitude between known positions before and after ice cover, although it has been suggested that some improvement may be obtained by interpolating along contours of planetary-geostrophic potential vorticity. Profiles with linearly interpolated positions represent 16% of the Southern Ocean Argo dataset; consequences arising from this approximation have not been quantified. Using three distinct datasets from the Weddell Gyre - 10 day satellite-tracked Argo floats, daily-tracked RAFOS-enabled floats, and a particle release simulation in the Southern Ocean State Estimate (SOSE) - we perform a data withholding experiment to assess position uncertainty in latitude-longitude and potential vorticity coordinates as a function of time since last fix. A spatial correlation analysis using the float data provides temperature and salinity uncertainty estimates as a function of distance error. Combining the spatial correlation scales and the position uncertainty, we estimate uncertainty in temperature and salinity as a function of duration of position loss. Maximum position uncertainty for interpolation during 8 months without position data is 116 {\textpm} 148 km for latitude-longitude and 92 {\textpm} 121 km for potential vorticity coordinates. The estimated maximum uncertainty in local temperature and salinity over the entire 2,000 m profiles during 8 months without position data is 0.66 {\textdegree}~C and 0.15 psu in the upper 300 m and 0.16 {\textdegree}~C and 0.01 psu below 300 m.
Keywords: Air/sea Flux Uncertainty, Salinity Uncertainty, Temperature Uncertainty, Under Ice Floats, Weddell Sea Circulation
Wang, Tianyu; Gille, Sarah T; Mazloff, Matthew R; Zilberman, Nathalie V; Du, Yan (2018). Numerical simulations to project Argo float positions in the mid-depth and deep southwest Pacific, Journal of Atmospheric and Oceanic TechnologyJournal of Atmospheric and Oceanic Technology.
Title: Numerical simulations to project Argo float positions in the mid-depth and deep southwest Pacific
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic TechnologyJournal of Atmospheric and Oceanic Technology
Author(s): Wang, Tianyu; Gille, Sarah T; Mazloff, Matthew R; Zilberman, Nathalie V; Du, Yan
Year: 2018
Formatted Citation: Wang, T., S. T. Gille, M. R. Mazloff, N. V. Zilberman, and Y. Du, 2018: Numerical simulations to project Argo float positions in the mid-depth and deep southwest Pacific. Journal of Atmospheric and Oceanic TechnologyJournal of Atmospheric and Oceanic Technology, https://doi.org/10.1175/JTECH-D-17-0214.1
Abstract: Argo float trajectories are simulated in the Southwest Pacific Basin (170{\textdegree}E-165{\textdegree}W, 25{\textdegree}S-45{\textdegree}S) using velocity fields from a 1/12{\textdegree} Southern Ocean model and a Lagrangian particle tracking model programmed to represent the vertical motions of profiling Argo floats. The system is applied to simulate both core Argo floats (typically parked at 1000-m depth and profiling to 2000-m depth) and Deep Argo floats (parked 500 m above the seafloor). The goal is to estimate Probability Density Functions (PDFs) predicting future float positions. Differences are expected in the trajectory statistics, largely because of limitations in the temporal and spatial resolution of the model fields and uncertainties associated with a random walk component included in the particle advection scheme to represent this unresolved variability. Nonetheless, the core Argo float displacements over ~100-day time intervals are mostly consistent with the derived PDFs, particularly in regions with stable mid-layer flows. For the Deep Argo floats, which are released in the open ocean and parked near the bottom, the simulations predict an average total displacement of less than 50 km within 100 days, in good agreement with the Deep Argo floats deployed as part of a pilot study. The study explores both the representativeness and the predictability of float displacements, with an aim to contribute to planning for the float observing system.
Formatted Citation: Russell, J. L. and Coauthors, 2018: Metrics for the Evaluation of the Southern Ocean in Coupled Climate Models and Earth System Models. J. Geophys. Res. Ocean., doi:10.1002/2017JC013461
Amrhein, Daniel E.; Wunsch, Carl; Marchal, Olivier; Forget, Gael; Amrhein, Daniel E.; Wunsch, Carl; Marchal, Olivier; Forget, Gael (2018). A Global Glacial Ocean State Estimate Constrained by Upper-Ocean Temperature Proxies, Journal of Climate, 19 (31), 8059-8079, 10.1175/JCLI-D-17-0769.1.
Title: A Global Glacial Ocean State Estimate Constrained by Upper-Ocean Temperature Proxies
Type: Journal Article
Publication: Journal of Climate
Author(s): Amrhein, Daniel E.; Wunsch, Carl; Marchal, Olivier; Forget, Gael; Amrhein, Daniel E.; Wunsch, Carl; Marchal, Olivier; Forget, Gael
Year: 2018
Formatted Citation: Amrhein, D. E., C. Wunsch, O. Marchal, G. Forget, D. E. Amrhein, C. Wunsch, O. Marchal, and G. Forget, 2018: A Global Glacial Ocean State Estimate Constrained by Upper-Ocean Temperature Proxies. J. Clim., 31(19), 8059-8079, doi:10.1175/JCLI-D-17-0769.1
Abstract: We use the method of least squares with Lagrange multipliers to fit an ocean general circulation model to the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) estimate of near sea surface temperature (NSST) at the Last Glacial Maximum (LGM; circa 23-19 thousand years ago). Compared to a modern simulation, the resulting global, last-glacial ocean state estimate, which fits the MARGO data within uncertainties in a free-running coupled ocean-sea ice simulation, has global-mean NSSTs that are 2°C lower and greater sea ice extent in all seasons in both the Northern and Southern Hemispheres. Increased brine rejection by sea ice formation in the Southern Ocean contributes to a stronger abyssal stratification set principally by salinity, qualitatively consistent with pore fluid measurements. The upper cell of the glacial Atlantic overturning circulation is deeper and stronger. Dye release experiments show similar distributions of Southern Ocean source waters in the glacial a...
Ubelmann, Clément; Dibarboure, Gérald; Dubois, Pierre (2018). A Cross-Spectral Approach to Measure the Error Budget of the SWOT Altimetry Mission over the Ocean, Journal of Atmospheric and Oceanic Technology, 4 (35), 845-857, 10.1175/JTECH-D-17-0061.1.
Title: A Cross-Spectral Approach to Measure the Error Budget of the SWOT Altimetry Mission over the Ocean
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Ubelmann, Clément; Dibarboure, Gérald; Dubois, Pierre
Year: 2018
Formatted Citation: Ubelmann, C., G. Dibarboure, and P. Dubois, 2018: A Cross-Spectral Approach to Measure the Error Budget of the SWOT Altimetry Mission over the Ocean. Journal of Atmospheric and Oceanic Technology, 35(4), 845-857, doi:10.1175/JTECH-D-17-0061.1
Formatted Citation: Fukumori, I., I. Fenty, G. Forget, P. Heimbach, C. King, and A. Nguyen, 2018: Data sets used in ECCO Version 4 Release 3., 1-11 pp. http://hdl.handle.net/1721.1/120472.
Thompson, Andrew F.; Stewart, Andrew L.; Spence, Paul; Heywood, Karen J. (2018). The Antarctic Slope Current in a Changing Climate, Reviews of Geophysics, 4 (56), 741-770, 10.1029/2018RG000624.
Title: The Antarctic Slope Current in a Changing Climate
Type: Journal Article
Publication: Reviews of Geophysics
Author(s): Thompson, Andrew F.; Stewart, Andrew L.; Spence, Paul; Heywood, Karen J.
Year: 2018
Formatted Citation: Thompson, A. F., A. L. Stewart, P. Spence, and K. J. Heywood, 2018: The Antarctic Slope Current in a Changing Climate. Reviews of Geophysics, 56(4), 741-770, doi:10.1029/2018RG000624
Formatted Citation: Dushaw, B. D. and Coauthors, 2017: Ocean Acoustic Tomography : a Missing Element of the Ocean Observing System. Proceedings Underwater Acoustics Conference and Exhibition, 12 pp. http://staff.washington.edu/dushaw/epubs/Dushaw_Tomography_UACE2017.pdf.
Abstract: Ocean acoustic tomography now has a long history with many observations and experiments that highlight the unique capabilities of this approach to detecting and understanding ocean variability. Examples include observations of deep mixing in the Greenland Sea, mode-1 internal tides radiating far into the ocean interior (coherent in time and space), relative vorticity on multiple scales, basin-wide and antipodal measures of temperature, barotropic currents, coastal processes in shallow water, and Arctic climate change. Despite the capabilities, tomography, and its simplified form thermometry, are not yet core observations within the Ocean Observing Systems (OOS). These observing systems could benefit greatly from applied acoustical oceanography, and both the world's climatic circumstance and the difficulty in ocean observation argue that all available techniques should be implemented. A perception that the existence of the Argo float system obviates the need for the acoustical observations has been shown to be false; observations of ocean variability by tomography are distinct from those of floats or gliders. The growing application of acoustical measurements as part of the observing system (e.g., IQOE orunderwater GPS systems) make tomography a natural component of OOSes. The developing INTAROS system is demonstrating the integration of diverse observations, including passive and active acoustical applications, into a coherent, operational system - part of the Arctic Ocean Observing System. Within the Framework for Ocean Observing (FOO), we reiterate the recommendation of the OceanObs'99 conference and advocate a tomography system in the western North Atlantic as an initial contribution. Such a system would provide unique measurements of large-scale temperature, barotropic currents, vorticity, fluxes, and abyssal variability, while providing tracking capabilities for deep floats and gliders. This initial design, and the sustained system that would evolve from it, would result in a more complete fit-for-purpose overall observing system for essential ocean variables (EOVs) and derived quantities.
Title: Improved ocean state estimation by controlling ocean-mixing: toward synthesis of ocean-mixing observations
Type: Journal Article
Publication: Oceanography in Japan
Author(s): Masuda, Shuhei
Year: 2017
Formatted Citation: Masuda, S., 2017: Improved ocean state estimation by controlling ocean-mixing: toward synthesis of ocean-mixing observations. Oceanography in Japan, 26(5), 209−215, http://kaiyo-gakkai.jp/jos/uminokenkyu/vol26/26-5/26-5-masuda.pdf
Abstract: Ocean-mixing plays an essential role in ocean currents, particularly meridional overturn- ing. In conjunction with increased observations, there has been a focus on synthesis of ocean- mixing data. This paper discusses current ocean state estimation and possible synthesis of ocean-mixing observations.
Keywords: data assimilation, ocean circulation, vertical mixing
Mu, Longjiang; Zhao, Jinping; Zhong, Wenli (2017). Regime shift of the dominant factor for halocline depth in the Canada Basin during 1990-2008, Acta Oceanologica Sinica, 1 (36), 35-43, 10.1007/s13131-016-0883-0.
Title: Regime shift of the dominant factor for halocline depth in the Canada Basin during 1990-2008
Formatted Citation: Mu, L., J. Zhao, and W. Zhong, 2017: Regime shift of the dominant factor for halocline depth in the Canada Basin during 1990-2008. Acta Oceanologica Sinica, 36(1), 35-43, doi:10.1007/s13131-016-0883-0
Bashmachnikov, I. L.; Belonenko, T. V.; Kuibin, P. A. (2017). Application of the theory of columnar Q-vortices with helical structure for the Lofoten vortex in the Norwegian Sea, Bulletin of Saint-Petersburg University Earth Sciences, 62 (3), 221-236.
Title: Application of the theory of columnar Q-vortices with helical structure for the Lofoten vortex in the Norwegian Sea
Type: Journal Article
Publication: Bulletin of Saint-Petersburg University Earth Sciences
Author(s): Bashmachnikov, I. L.; Belonenko, T. V.; Kuibin, P. A.
Year: 2017
Formatted Citation: Bashmachnikov, I. L., T. V. Belonenko, and P. A. Kuibin, 2017: Application of the theory of columnar Q-vortices with helical structure for the Lofoten vortex in the Norwegian Sea. Bulletin of Saint-Petersburg University Earth Sciences, 3(62), 221-236, https://dspace.spbu.ru/bitstream/11701/8985/1/01-Bashmachnikov.pdf
Abstract: In this paper, dynamic characteristics of mesoscale vortices in the ocean are considered using the theory of columnar vortices with a helical structure. The radial profile of the relative vorticity is ap- proximated with the Q-distribution. Expressions connecting the distributions of the horizontal and vertical velocity components in this type of vortices are obtained. The limitations for the applicability of the analytical solution are derived. The advantages and disadvantages of this model are shown in comparison with the radial distributions of the corresponding parameters in Scully and in Rayleigh vortices. In particular, it is shown that the Q-distribution can, in some sense, be considered as a com- promise solution between the two distributions above. The theory of columnar Q-vortices with helical structure is applied to the permanently existing anticyclonic Lofoten vortex of the Norwegian Sea. The mean radial distributions of various dynamics characteristics of the Lofoten vortex are obtained using simulations with the regional hydrodynamic model MIT. The reasons for formation of the observed vertical velocity structure are analyzed. It is shown that, in contrast to atmospheric synoptic structures, divergence of Ekman fluxes in the bottom layer affects only the lower part of the vortex. In the upper ocean, ascending vertical motion is observed in the Lofoten vortex. It is assumed that horizontal dis- persion of vortex energy, the most intense in the surface layer, plays an essential role in the formation of the field of vertical velocities in the upper part of its core.
Bashmachnikov, I.L.; Sokolovskiy, M.A.; Belonenko, T.V.; Volkov, Denis L.; Isachsen, P.E.; Carton, X. (2017). On the vertical structure and stability of the Lofoten vortex in the Norwegian Sea, Deep Sea Research Part I: Oceanographic Research Papers (128), 1-27, 10.1016/j.dsr.2017.08.001.
Formatted Citation: Bashmachnikov, I., M. Sokolovskiy, T. Belonenko, D. L. Volkov, P. Isachsen, and X. Carton, 2017: On the vertical structure and stability of the Lofoten vortex in the Norwegian Sea. Deep Sea Research Part I: Oceanographic Research Papers, 128, 1-27, doi:10.1016/j.dsr.2017.08.001
Formatted Citation: Timmermans, M., J. Marshall, A. Proshutinsky, and J. Scott, 2017: Seasonally derived components of the Canada Basin halocline. Geophys. Res. Lett., 44(10), 5008-5015, doi:10.1002/2017GL073042
Ungermann, Mischa; Tremblay, L. Bruno; Martin, Torge; Losch, Martin (2017). Impact of the ice strength formulation on the performance of a sea ice thickness distribution model in the Arctic, Journal of Geophysical Research: Oceans, 3 (122), 2090-2107, 10.1002/2016JC012128.
Title: Impact of the ice strength formulation on the performance of a sea ice thickness distribution model in the Arctic
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Ungermann, Mischa; Tremblay, L. Bruno; Martin, Torge; Losch, Martin
Year: 2017
Formatted Citation: Ungermann, M., L. B. Tremblay, T. Martin, and M. Losch, 2017: Impact of the ice strength formulation on the performance of a sea ice thickness distribution model in the Arctic. J. Geophys. Res. Ocean., 122(3), 2090-2107, doi:10.1002/2016JC012128
Gelderloos, Renske; Haine, Thomas W. N.; Koszalka, Inga M.; Magaldi, Marcello G. (2017). Seasonal Variability in Warm-Water Inflow toward Kangerdlugssuaq Fjord, Journal of Physical Oceanography, 7 (47), 1685-1699, 10.1175/JPO-D-16-0202.1.
Title: Seasonal Variability in Warm-Water Inflow toward Kangerdlugssuaq Fjord
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Gelderloos, Renske; Haine, Thomas W. N.; Koszalka, Inga M.; Magaldi, Marcello G.
Year: 2017
Formatted Citation: Gelderloos, R., T. W. N. Haine, I. M. Koszalka, and M. G. Magaldi, 2017: Seasonal Variability in Warm-Water Inflow toward Kangerdlugssuaq Fjord. Journal of Physical Oceanography, 47(7), 1685-1699, doi:10.1175/JPO-D-16-0202.1
Winska, Malgorzata; Nastula, Jolanta; Salstein, David (2017). Hydrological excitation of polar motion by different variables from the GLDAS models, Journal of Geodesy, 12 (91), 1461-1473, 10.1007/s00190-017-1036-8.
Title: Hydrological excitation of polar motion by different variables from the GLDAS models
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Winska, Malgorzata; Nastula, Jolanta; Salstein, David
Year: 2017
Formatted Citation: Winska, M., J. Nastula, and D. Salstein, 2017: Hydrological excitation of polar motion by different variables from the GLDAS models. Journal of Geodesy, 91(12), 1461-1473, doi:10.1007/s00190-017-1036-8
Title: Modelling the long-term evolution of worst-case Arctic oil spills
Type: Journal Article
Publication: Marine Pollution Bulletin
Author(s): Blanken, Hauke; Tremblay, Louis Bruno; Gaskin, Susan; Slavin, Alexander
Year: 2017
Formatted Citation: Blanken, H., L. B. Tremblay, S. Gaskin, and A. Slavin, 2017: Modelling the long-term evolution of worst-case Arctic oil spills. Marine Pollution Bulletin, 116(1-2), 315-331, doi:10.1016/j.marpolbul.2016.12.070
Koldunov, Nikolay V.; Köhl, Armin; Serra, Nuno; Stammer, Detlef (2017). Sea ice assimilation into a coupled ocean-sea ice model using its adjoint, The Cryosphere, 5 (11), 2265-2281, 10.5194/tc-11-2265-2017.
Title: Sea ice assimilation into a coupled ocean-sea ice model using its adjoint
Type: Journal Article
Publication: The Cryosphere
Author(s): Koldunov, Nikolay V.; Köhl, Armin; Serra, Nuno; Stammer, Detlef
Year: 2017
Formatted Citation: Koldunov, N. V., A. Köhl, N. Serra, and D. Stammer, 2017: Sea ice assimilation into a coupled ocean-sea ice model using its adjoint. Cryosph., 11(5), 2265-2281, doi:10.5194/tc-11-2265-2017
Abstract: Satellite sea ice concentrations (SICs), together with several ocean parameters, are assimilated into a regional Arctic coupled ocean-sea ice model covering the period of 2000-2008 using the adjoint method. There is substantial improvement in the representation of the SIC spatial distribution, in particular with respect to the position of the ice edge and to the concentrations in the central parts of the Arctic Ocean during summer months. Seasonal cycles of total Arctic sea ice area show an overall improvement. During summer months, values of sea ice extent (SIE) integrated over the model domain become underestimated compared to observations, but absolute differences of mean SIE to the data are reduced in nearly all months and years. Along with the SICs, the sea ice thickness fields also become closer to observations, providing added value by the assimilation. Very sparse ocean data in the Arctic, corresponding to a very small contribution to the cost function, prevent sizable improvements of assimilated ocean variables, with the exception of the sea surface temperature.
Title: Intraseasonal variability of currents along east coast of India
Type: Thesis
Publication:
Author(s): Mukherjee, Arnab
Year: 2017
Formatted Citation: Mukherjee, A., 2017: Intraseasonal variability of currents along east coast of India., 194 pp. http://irgu.unigoa.ac.in/drs/bitstream/handle/unigoa/5539/mukherjee_a_2017.pdf?sequence=1.
Tamsitt, Veronica; Drake, Henri F; Morrison, Adele K; Talley, Lynne D; Dufour, Carolina O; Gray, Alison R; Griffies, Stephen M; Mazloff, Matthew R; Sarmiento, Jorge L; Wang, Jinbo; Weijer, Wilbert (2017). Spiraling pathways of global deep waters to the surface of the Southern Ocean, Nature Communications (8), 172, 0.1038/s41467-017-00197-0.
Title: Spiraling pathways of global deep waters to the surface of the Southern Ocean
Type: Journal Article
Publication: Nature Communications
Author(s): Tamsitt, Veronica; Drake, Henri F; Morrison, Adele K; Talley, Lynne D; Dufour, Carolina O; Gray, Alison R; Griffies, Stephen M; Mazloff, Matthew R; Sarmiento, Jorge L; Wang, Jinbo; Weijer, Wilbert
Year: 2017
Formatted Citation: Tamsitt, V. and Coauthors, 2017: Spiraling pathways of global deep waters to the surface of the Southern Ocean. Nature Communications, 8, 172, doi:0.1038/s41467-017-00197-0
Abstract: Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the Antarctic Circumpolar Current via southward flow along the boundaries of the three ocean basins, before spiraling southeastward and upward through the Antarctic Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the Antarctic Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30{\textdegree} S to the mixed layer is ~60-90 years.
Mazloff, M R; Sallée, J.-B.; Menezes, V V; Macdonald, A M; Meredith, M P; Newman, L; Pellichero, V; Roquet, F; Swart, S; W\r ahlin, A (2017). Southern Ocean in State of the Climate in 2016, Bull. Amer. Meteor. Soc. (98).
Title: Southern Ocean in State of the Climate in 2016
Type: Journal Article
Publication: Bull. Amer. Meteor. Soc.
Author(s): Mazloff, M R; Sallée, J.-B.; Menezes, V V; Macdonald, A M; Meredith, M P; Newman, L; Pellichero, V; Roquet, F; Swart, S; W\r ahlin, A
Year: 2017
Formatted Citation: Mazloff, M. R. and Coauthors, 2017: Southern Ocean in State of the Climate in 2016. Bull. Amer. Meteor. Soc., 98
Abstract:
Keywords:
ECCO Products Used: SOSE
URL:
Other URLs:
Villas Bôas, Ana B; Gille, Sarah T; Mazloff, Matthew R; Cornuelle, Bruce D (2017). Characterization of the Deep-Water Surface Wave Variability in the California Current Region, Journal of Geophysical Research: Oceans, 10.1002/2017JC013280.
Title: Characterization of the Deep-Water Surface Wave Variability in the California Current Region
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Villas Bôas, Ana B; Gille, Sarah T; Mazloff, Matthew R; Cornuelle, Bruce D
Year: 2017
Formatted Citation: Villas Bôas, A. B., S. T. Gille, M. R. Mazloff, and B. D. Cornuelle, 2017: Characterization of the Deep-Water Surface Wave Variability in the California Current Region. J. Geophys. Res. Ocean., doi:10.1002/2017JC013280
Abstract: n/a
Keywords: Remote sensing and electromagnetic processes, SWOT, Surface waves and tides, air/sea interactions, california current, expansion fan winds, satellite altimetry, surface waves
Bowman, Kevin W.; Liu, J; Bloom, A A; Parazoo, N C; Lee, M; Jiang, Z; Menemenlis, Dimitris; Gierach, M M; Collatz, G J; Gurney, K R; Wunch, D (2017). Global and Brazilian Carbon Response to El Niño Modoki 2011-2010, Earth and Space Science, 10 (4), 637-660, 10.1002/2016EA000204.
Title: Global and Brazilian Carbon Response to El Niño Modoki 2011-2010
Type: Journal Article
Publication: Earth and Space Science
Author(s): Bowman, Kevin W.; Liu, J; Bloom, A A; Parazoo, N C; Lee, M; Jiang, Z; Menemenlis, Dimitris; Gierach, M M; Collatz, G J; Gurney, K R; Wunch, D
Year: 2017
Formatted Citation: Bowman, K. W. and Coauthors, 2017: Global and Brazilian Carbon Response to El Niño Modoki 2011-2010. Earth and Space Science, 4(10), 637-660, doi:10.1002/2016EA000204
Abstract: The El Niño Modoki in 2010 led to historic droughts in Brazil. In order to understand its impact on carbon cycle variability, we derive the 2011?2010 annual carbon flux change (δF?) globally and specifically to Brazil using the NASA Carbon Monitoring System Flux (CMS-Flux) framework. Satellite observations of CO2, CO, and solar-induced fluorescence (SIF) are ingested into a 4D-variational assimilation system driven by carbon cycle models to infer spatially resolved carbon fluxes including net ecosystem production, biomass burning, and gross primary productivity (GPP). The global 2011?2010 net carbon flux change was estimated to be δF?=?1.60 PgC, while the Brazilian carbon flux change was ?0.24 ± 0.11 PgC. This estimate is broadly within the uncertainty of previous aircraft-based estimates restricted to the Amazon basin. The 2011?2010 biomass burning change in Brazil was ?0.24 ± 0.036 PgC, which implies a near-zero 2011?2010 change of the net ecosystem production (NEP): The near-zero NEP change is the result of quantitatively comparable increases GPP (0.31 ± 0.20 PgC) and respiration in 2011. Comparisons between Brazilian and global component carbon flux changes reveal complex interactions between the processes controlling annual land-atmosphere CO2 exchanges. These results show the potential of multiple satellite observations to help quantify and spatially resolve the response of productivity and respiration fluxes to climate variability.
Ngeve, Magdalene N; Van der Stocken, Tom; Menemenlis, Dimitris; Koedam, Nico; Triest, Ludwig (2017). Hidden founders? Strong bottlenecks and fine-scale genetic structure in mangrove populations of the Cameroon Estuary complex, Hydrobiologia, 1 (803), 189-207, 10.1007/s10750-017-3369-y.
Title: Hidden founders? Strong bottlenecks and fine-scale genetic structure in mangrove populations of the Cameroon Estuary complex
Type: Journal Article
Publication: Hydrobiologia
Author(s): Ngeve, Magdalene N; Van der Stocken, Tom; Menemenlis, Dimitris; Koedam, Nico; Triest, Ludwig
Year: 2017
Formatted Citation: Ngeve, M. N., T. Van der Stocken, D. Menemenlis, N. Koedam, and L. Triest, 2017: Hidden founders? Strong bottlenecks and fine-scale genetic structure in mangrove populations of the Cameroon Estuary complex. Hydrobiologia, 803(1), 189-207, doi:10.1007/s10750-017-3369-y
Abstract: Fine-scale genetic structure (FSGS) is common in plants, driven by several ecological and evolutionary processes, among which is gene flow. Mangrove trees rely on ocean surface currents to spread their hydrochorous propagules through space. Since pollen dispersal is generally restricted to local scales, high level of short-distance propagule dispersal is expected to result in FSGS in Rhizophora spp. We investigated FSGS, recent bottleneck events, as well as historical and contemporary expansion patterns in Rhizophora racemosa populations from the entire coast of Cameroon, using 11 polymorphic microsatellite markers. Populations of the Cameroon Estuary complex (CEC) showed significant FSGS and significant reduction in effective population sizes (recent bottlenecks), compared to the other areas. Additionally, our results indicate stark differences between historical and contemporary expansion models. These suggest that contemporary processes such as restricted propagule dispersal, bottleneck events from high indirect and direct anthropogenic pressure, and recolonization by founders from ancient local pockets/refugia most plausibly shape the patterns of FSGS in the CEC.
Formatted Citation: Chen, W., J. Li, J. Ray, and M. Cheng, 2017: Improved geophysical excitations constrained by polar motion observations and GRACE/SLR time-dependent gravity. Geodesy and Geodynamics, 8(6), 377-388, doi:10.1016/j.geog.2017.04.006
Abstract: At seasonal and intraseasonal time scales, polar motions are mainly excited by angular momentum fluctuations due to mass redistributions and relative motions in the atmosphere, oceans, and continental water, snow, and ice, which are usually provided by various global atmospheric, oceanic, and hydrological models (some with meteorological observations assimilated; e.g., NCEP, ECCO, ECMWF, OMCT and LSDM etc.). Unfortunately, these model outputs are far from perfect and have notable discrepancies with respect to polar motion observations, due to non-uniform distributions of meteorological observatories, as well as theoretical approximations and non-global mass conservation in these models. In this study, the LDC (Least Difference Combination) method is adopted to obtain some improved atmospheric, oceanic, and hydrological/crospheric angular momentum (AAM, OAM and HAM/CAM, respectively) functions and excitation functions (termed as the LDCgsm solutions). Various GRACE (Gravity Recovery and Climate Experiment) and SLR (Satellite Laser Ranging) geopotential data are adopted to correct the non-global mass conservation problem, while polar motion data are used as general constraints. The LDCgsm solutions can reveal not only periodic fluctuations but also secular trends in AAM, OAM and HAM/CAM, and are in better agreement with polar motion observations, reducing the unexplained excitation to the level of about 5.5 mas (standard derivation value; about 1/5-1/4 of those corresponding to the original model outputs).
Keywords: Atmospheric, GRACE, Least difference combination, Polar motion, SLR, and hydrological/crospheric excitation, oceanic
Nguyen, An; Ocaña, Victor; Garg, Vikram; Heimbach, Patrick; Toole, John; Krishfield, Richard; Lee, Craig; Rainville, Luc (2017). On the Benefit of Current and Future ALPS Data for Improving Arctic Coupled Ocean-Sea Ice State Estimation, Oceanography, 2 (30), 69-73, 10.5670/oceanog.2017.223.
Formatted Citation: Nguyen, A., V. Ocaña, V. Garg, P. Heimbach, J. Toole, R. Krishfield, C. Lee, and L. Rainville, 2017: On the Benefit of Current and Future ALPS Data for Improving Arctic Coupled Ocean-Sea Ice State Estimation. Oceanography, 30(2), 69-73, doi:10.5670/oceanog.2017.223
Abstract: Autonomous and Lagrangian platforms and sensors (ALPS) have revolutionized the way the subsurface ocean is observed. The synergy between ALPS-based observations and coupled ocean-sea ice state and parameter estimation as practiced in the Arctic Subpolar gyre sTate Estimate (ASTE) project is illustrated through several examples. In the western Arctic, Ice- Tethered Pro lers have been providing important hydrographic constraints of the water column down to 800 m depth since 2004. ASTE takes advantage of these detailed constraints to infer vertical pro les of diapycnal mixing rates in the central Canada Basin. The state estimation framework is also used to explore the potential utility of Argo-type oats in regions with sparse data coverage, such as the eastern Arctic and the seasonal ice zones. Finally, the framework is applied to identify potential deployment sites that optimize the impact of oat measurements on bulk oceanographic quantities of interest.
Title: Global coupled sea ice-ocean state estimation
Type: Journal Article
Publication: Climate Dynamics
Author(s): Fenty, Ian; Menemenlis, Dimitris; Zhang, Hong
Year: 2017
Formatted Citation: Fenty, I., D. Menemenlis, and H. Zhang, 2017: Global coupled sea ice-ocean state estimation. Climate Dynamics, 49(3), 931-956, doi:10.1007/s00382-015-2796-6
Other URLs: http://link.springer.com/10.1007/s00382-015-2796-6
Spreen, Gunnar; Kwok, Ronald; Menemenlis, Dimitris; Nguyen, An T (2017). Sea-ice deformation in a coupled ocean-sea-ice model and in satellite remote sensing data, Cryosph., 1, 1-37, 10.5194/tc-2016-13.
Title: Sea-ice deformation in a coupled ocean-sea-ice model and in satellite remote sensing data
Type: Journal Article
Publication: Cryosph.
Author(s): Spreen, Gunnar; Kwok, Ronald; Menemenlis, Dimitris; Nguyen, An T
Year: 2017
Formatted Citation: Spreen, G., R. Kwok, D. Menemenlis, and A. T. Nguyen, 2017: Sea-ice deformation in a coupled ocean-sea-ice model and in satellite remote sensing data. Cryosph.(1), 1-37, doi:10.5194/tc-2016-13
Abstract: A realistic representation of sea-ice deformation in models is important for accurate simulation of the sea-ice mass balance. Simulated sea-ice deformation from numerical simulations with 4.5, 9, and 18 km horizontal grid spacing and a viscous-plastic (VP) sea-ice rheology are compared with synthetic aperture radar (SAR) satellite observations (RGPS, RADARSAT Geophysical Processor System) for the time period 1996-2008. All three simulations can reproduce the large-scale ice deformation patterns, but small-scale sea- ice deformations and linear kinematic features (LKFs) are not adequately reproduced. The mean sea-ice total deforma- tion rate is about 40 % lower in all model solutions than in the satellite observations, especially in the seasonal sea-ice zone. A decrease in model grid spacing, however, produces a higher density and more localized ice deformation fea- tures. The 4.5 km simulation produces some linear kinematic features, but not with the right frequency. The dependence on length scale and probability density functions (PDFs) of absolute divergence and shear for all three model solutions show a power-law scaling behavior similar to RGPS obser- vations, contrary to what was found in some previous studies. Overall, the 4.5km simulation produces the most realistic divergence, vorticity, and shear when compared with RGPS data. This study provides an evaluation of high and coarse- resolution viscous-plastic sea-ice simulations based on spa- tial distribution, time series, and power-law scaling metrics.
Savage, Anna C; Arbic, Brian K; Alford, Matthew H; Ansong, Joseph K; Farrar, J Thomas; Menemenlis, Dimitris; O'Rourke, Amanda K; Richman, James G; Shriver, Jay F; Voet, Gunnar; Wallcraft, Alan J; Zamudio, Luis (2017). Spectral decomposition of internal gravity wave sea surface height in global models, J. Geophys. Res. Ocean. (122), 10.1002/2017JC013009.
Title: Spectral decomposition of internal gravity wave sea surface height in global models
Type: Journal Article
Publication: J. Geophys. Res. Ocean.
Author(s): Savage, Anna C; Arbic, Brian K; Alford, Matthew H; Ansong, Joseph K; Farrar, J Thomas; Menemenlis, Dimitris; O'Rourke, Amanda K; Richman, James G; Shriver, Jay F; Voet, Gunnar; Wallcraft, Alan J; Zamudio, Luis
Year: 2017
Formatted Citation: Savage, A. C. and Coauthors, 2017: Spectral decomposition of internal gravity wave sea surface height in global models. J. Geophys. Res. Ocean., 122, doi:10.1002/2017JC013009
Abstract: Two global ocean models ranging in horizontal resolution from 1/128 to 1/488 are used to study the space and time scales of sea surface height (SSH) signals associated with internal gravity waves (IGWs). Frequency-horizontal wavenumber SSH spectral densities are computed over seven regions of the world ocean from two simulations of the HYbrid Coordinate Ocean Model (HYCOM) and three simulations of the Massachusetts Institute of Technology general circulation model (MITgcm). High wavenumber, high-frequency SSH variance follows the predicted IGW linear dispersion curves. The realism of high-frequency motions (>0:87 cpd) in the models is tested through comparison of the frequency spectral density of dynamic height variance computed from the highest-resolution runs of each model (1/258 HYCOM and 1/488 MITgcm) with dynamic height variance frequency spectral density computed from nine in situ profiling instruments. These high-frequency motions are of particular interest because of their contributions to the small-scale SSH variability that will be observed on a global scale in the upcoming Surface Water and Ocean Topography (SWOT) satellite altimetry mission. The variance at supertidal frequencies can be comparable to the tidal and low-frequency variance for high wavenumbers (length scales smaller than 50 km), especially in the higher-resolution simulations. In the highest-resolution simulations, the high-frequency variance can be greater than the low-frequency variance at these scales.
Vazquez-Cuervo, Jorge; Torres, Hector S; Menemenlis, Dimitris; Chin, Toshio M; Armstrong, Edward M (2017). Relationship between SST gradients and upwelling off Peru and Chile: model/satellite data analysis, Int. J. Remote Sens., 23 (38), 6599-6622, 10.1080/01431161.2017.1362130.
Title: Relationship between SST gradients and upwelling off Peru and Chile: model/satellite data analysis
Type: Journal Article
Publication: Int. J. Remote Sens.
Author(s): Vazquez-Cuervo, Jorge; Torres, Hector S; Menemenlis, Dimitris; Chin, Toshio M; Armstrong, Edward M
Year: 2017
Formatted Citation: Vazquez-Cuervo, J., H. S. Torres, D. Menemenlis, T. M. Chin, and E. M. Armstrong, 2017: Relationship between SST gradients and upwelling off Peru and Chile: model/satellite data analysis. Int. J. Remote Sens., 38(23), 6599-6622, doi:10.1080/01431161.2017.1362130
Abstract: The upwelling system off Peru/Chile is characterized by significant mesoscale to submesoscale surface variability that results from the instability of the coastal currents (due to the strong vertical and horizontal shears) and to the marked density cross-shore gradients (associated with the mean upwelling). Here we investigate to what extent upwelling intensity can be inferred from sea surface tem- perature (SST) derived from remote sensing. As a first step in validation, a comparison between SST observations is performed, which indicates that the 1 km gridded multi-scale ultra-high-resolu- tion (MUR) SST data set is defining a zone of maximum SST gradi- ents closer to shore than the low-resolution National Centers for Environmental Information 0.25° resolution data set. Two model versions, at nominal resolutions of 2 km and 4 km, of the Massachusetts Institute of Technology general circulation model are analysed. A high-resolution version at 2 km is examined for the period 13 September 2011-23 January 2013, while a 4 km version is examined for 6 March 2011-22 April 2013. MUR shows maxima SST gradients in the range of 0.03 ± 0.02 K km−1 while the model showed higher gradients around 0.05 ± 0.02 K km−1. Based on coherence spectra, the relationship between upwelling rate (as inferred from the vertical velocity) and SST gradient is documented in the model from intraseasonal to annual timescales. It suggests that changes in SST gradient magnitudes are related to changes in the intensity of coastal upwelling off Peru and Chile. Such a relation- ship between SST gradients and vertical velocity would allow for the use of satellite-derived SSTs to monitor the intensity of coastal upwelling from the intraseasonal to annual timescales.
Nakayama, Yoshihiro; Menemenlis, Dimitris; Schodlok, Michael P; Rignot, Eric J (2017). Amundsen and Bellingshausen Seas simulation with optimized ocean, sea ice, and thermodynamic ice shelf model parameters, J. Geophys. Res. Ocean., 1-16, 10.1002/2016JC012538.
Title: Amundsen and Bellingshausen Seas simulation with optimized ocean, sea ice, and thermodynamic ice shelf model parameters
Type: Journal Article
Publication: J. Geophys. Res. Ocean.
Author(s): Nakayama, Yoshihiro; Menemenlis, Dimitris; Schodlok, Michael P; Rignot, Eric J
Year: 2017
Formatted Citation: Nakayama, Y., D. Menemenlis, M. P. Schodlok, and E. J. Rignot, 2017: Amundsen and Bellingshausen Seas simulation with optimized ocean, sea ice, and thermodynamic ice shelf model parameters. J. Geophys. Res. Ocean., 1-16, doi:10.1002/2016JC012538
Abstract:
Keywords: Amundsen Sea, Bellingshausen Sea, Glacial melt water, Pine Island Glacier, Thermocline, Winter water
ECCO Products Used: IceSheet;LLC270
URL:
Other URLs:
Abbondanza, Claudio; Chin, Toshio M; Gross, Richard S; Heflin, Michael B; Parker, Jay W; Soja, Benedikt S; van Dam, Tonie; Wu, Xiaoping (2017). JTRF2014, the JPL Kalman filter and smoother realization of the International Terrestrial Reference System, Journal of Geophysical Research: Solid Earth, 10 (122), 8474-8510, 10.1002/2017JB014360.
Title: JTRF2014, the JPL Kalman filter and smoother realization of the International Terrestrial Reference System
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Abbondanza, Claudio; Chin, Toshio M; Gross, Richard S; Heflin, Michael B; Parker, Jay W; Soja, Benedikt S; van Dam, Tonie; Wu, Xiaoping
Year: 2017
Formatted Citation: Abbondanza, C., T. M. Chin, R. S. Gross, M. B. Heflin, J. W. Parker, B. S. Soja, T. van Dam, and X. Wu, 2017: JTRF2014, the JPL Kalman filter and smoother realization of the International Terrestrial Reference System. Journal of Geophysical Research: Solid Earth, 122(10), 8474-8510, doi:10.1002/2017JB014360
Abstract: We present and discuss JTRF2014, the Terrestrial Reference Frame (TRF) the Jet Propulsion Laboratory constructed by combining space?geodetic inputs from very long baseline interferometry (VLBI), satellite laser ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler orbitography and radiopositioning integrated by satellite submitted for the realization of ITRF2014. Determined through a Kalman filter and Rauch?Tung?Striebel smoother assimilating position observations, Earth orientation parameters, and local ties, JTRF2014 is a subsecular, time series?based TRF whose origin is at the quasi?instantaneous center of mass (CM) as sensed by SLR and whose scale is determined by the quasi?instantaneous VLBI and SLR scales. The dynamical evolution of the positions accounts for a secular motion term, annual, and semiannual periodic modes. Site?dependent variances based on the analysis of loading displacements induced by mass redistributions of terrestrial fluids have been used to control the extent of random walk adopted in the combination. With differences in the amplitude of the annual signal within the range 0.5?0.8 mm, JTRF2014?derived center of network?to?center of mass (CM?CN) is in remarkable agreement with the geocenter motion obtained via spectral inversion of GNSS, Gravity Recovery and Climate Experiment (GRACE) observations and modeled ocean bottom pressure from Estimating the Circulation and Climate of the Ocean (ECCO). Comparisons of JTRF2014 to ITRF2014 suggest high?level consistency with time derivatives of the Helmert transformation parameters connecting the two frames below 0.18 mm/yr and weighted root?mean?square differences of the polar motion (polar motion rate) in the order of 30 ?as (17 ?as/d).
Keywords: Earth rotation, GNSS VLBI SLR DORIS, Kalman filter, Terrestrial Reference Frames, geocenter motion, time series
Song, Xiangzhou; Yu, Lisan (2017). Air-sea heat flux climatologies in the Mediterranean Sea: Surface energy balance and its consistency with ocean heat storage, Journal of Geophysical Research: Oceans, 5 (122), 4068-4087, 10.1002/2016JC012254.
Title: Air-sea heat flux climatologies in the Mediterranean Sea: Surface energy balance and its consistency with ocean heat storage
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Song, Xiangzhou; Yu, Lisan
Year: 2017
Formatted Citation: Song, X., and L. Yu, 2017: Air-sea heat flux climatologies in the Mediterranean Sea: Surface energy balance and its consistency with ocean heat storage. J. Geophys. Res. Ocean., 122(5), 4068-4087, doi:10.1002/2016JC012254
Karspeck, A R; Stammer, D; Köhl, A; Danabasoglu, G; Balmaseda, M; Smith, D M; Fujii, Y; Zhang, S; Giese, B; Tsujino, H; Rosati, A (2017). Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products, Climate Dynamics, 3 (49), 957-982, 10.1007/s00382-015-2787-7.
Title: Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products
Type: Journal Article
Publication: Climate Dynamics
Author(s): Karspeck, A R; Stammer, D; Köhl, A; Danabasoglu, G; Balmaseda, M; Smith, D M; Fujii, Y; Zhang, S; Giese, B; Tsujino, H; Rosati, A
Year: 2017
Formatted Citation: Karspeck, A. R. and Coauthors, 2017: Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products. Climate Dynamics, 49(3), 957-982, doi:10.1007/s00382-015-2787-7
Abstract: The mean and variability of the Atlantic meridional overturning circulation (AMOC), as represented in six ocean reanalysis products, are analyzed over the period 1960-2007. Particular focus is on multi-decadal trends and interannual variability at 26.5°N and 45°N. For four of the six reanalysis products, corresponding reference simulations obtained from the same models and forcing datasets but without the imposition of subsurface data constraints are included for comparison. An emphasis is placed on identifying general characteristics of the reanalysis representation of AMOC relative to their reference simulations without subsurface data constraints. The AMOC as simulated in these two sets are presented in the context of results from the Coordinated Ocean-ice Reference Experiments phase II (CORE-II) effort, wherein a common interannually varying atmospheric forcing data set was used to force a large and diverse set of global ocean-ice models. Relative to the reference simulations and CORE-II forced model simulations it is shown that (1) the reanalysis products tend to have greater AMOC mean strength and enhanced variance and (2) the reanalysis products are less consistent in their year-to-year AMOC changes. We also find that relative to the reference simulations (but not the CORE-II forced model simulations) the reanalysis products tend to have enhanced multi-decadal trends (from 1975-1995 to 1995-2007) in the mid to high latitudes of the northern hemisphere.
Vinogradova, Nadya T.; Ponte, Rui M. (2017). In Search of Fingerprints of the Recent Intensification of the Ocean Water Cycle, Journal of Climate, 14 (30), 5513-5528, 10.1175/JCLI-D-16-0626.1.
Title: In Search of Fingerprints of the Recent Intensification of the Ocean Water Cycle
Type: Journal Article
Publication: Journal of Climate
Author(s): Vinogradova, Nadya T.; Ponte, Rui M.
Year: 2017
Formatted Citation: Vinogradova, N. T., and R. M. Ponte, 2017: In Search of Fingerprints of the Recent Intensification of the Ocean Water Cycle. J. Clim., 30(14), 5513-5528, doi:10.1175/JCLI-D-16-0626.1
Abstract: Unprecedented changes in Earth's water budget and a recent boom in salinity observations prompted the use of long-term salinity trends to fingerprint the amount of freshwater entering and leaving the oceans (the ocean water cycle). Here changes in the ocean water cycle in the past two decades are examined to evaluate whether the rain-gauge notion can be extended to shorter time scales. Using a novel framework it is demonstrated that there have been persistent changes (defined as significant trends) in both salinity and the ocean water cycle in many ocean regions, including the subtropical gyres in both hemispheres, low latitudes of the tropical Pacific, the North Atlantic Subpolar Gyre, and the Arctic Ocean. On average, the ocean water cycle has amplified by approximately 5% since 1993, but strong regional variations exist (as well as dependency on the surface freshwater flux products chosen). Despite an intensified ocean water cycle in the last two decades, changes in surface salinity do not follow expected patterns of amplified salinity contrasts, challenging the perception that if it rains more the seas always get fresher and if it evaporates more the seas always get saltier. These findings imply a time of emergence of anthropogenic hydrological signals shorter in surface freshwater fluxes than in surface salinity and point to the importance of ocean circulation, salt transports, and natural climate variability in shaping patterns of decadal change in surface salinity. Therefore, the use of salinity measurements in conjunction with ocean salt fluxes can provide a more meaningful way of fingerprinting changes in the global water cycle on decadal time scales.
Ito, Takamitsu; Wang, Ou (2017). Transit Time Distribution based on the ECCO-JPL Ocean Data Assimilation, Journal of Marine Systems (167), 1-10, 10.1016/j.jmarsys.2016.10.015.
Title: Transit Time Distribution based on the ECCO-JPL Ocean Data Assimilation
Type: Journal Article
Publication: Journal of Marine Systems
Author(s): Ito, Takamitsu; Wang, Ou
Year: 2017
Formatted Citation: Ito, T., and O. Wang, 2017: Transit Time Distribution based on the ECCO-JPL Ocean Data Assimilation. Journal of Marine Systems, 167, 1-10, doi:10.1016/j.jmarsys.2016.10.015
Abstract: Oceanic water mass is a mixture of waters with varying ages, and the Transit Time Distribution (TTD) measures its age spectrum. We construct a model-based TTD using the data-constrained circulation fields from the ECCO-JPL Ocean Data Assimilation, and test it against the observed and directly simulated distribution of pCFC-11 from the Pacific and Atlantic basins. The ECCO-JPL circulation provides overall reliable estimates of the upper ocean ventilation rates suitable for biogeochemical studies. Observed distributions of pCFC-11 in the upper ocean thermocline are well reproduced by the convolution integral of the model-based TTD (mean bias<6%, spatial correlation>0.87) but there are significant regional biases in particular near the base of the thermocline and in the deep water formation regions. The model underestimates the deep pCFC-11 (>2000m) in the North Atlantic and in the Southern Ocean. The ratio between the mean and the spread of the age spectrum (Γ/Δ) is close to unity (mean=1.04, median=0.99) in the ventilated thermocline of the Pacific basin but there are significant regional variations of the ratio.
Keywords: CFC-11, Ocean Data Assimilation, Transit Time Distribution
Craig, Philip M.; Ferreira, David; Methven, John (2017). The contrast between Atlantic and Pacific surface water fluxes, Tellus A: Dynamic Meteorology and Oceanography, 1 (69), 1330454, 10.1080/16000870.2017.1330454.
Title: The contrast between Atlantic and Pacific surface water fluxes
Type: Journal Article
Publication: Tellus A: Dynamic Meteorology and Oceanography
Author(s): Craig, Philip M.; Ferreira, David; Methven, John
Year: 2017
Formatted Citation: Craig, P. M., D. Ferreira, and J. Methven, 2017: The contrast between Atlantic and Pacific surface water fluxes. Tellus A: Dynamic Meteorology and Oceanography, 69(1), 1330454, doi:10.1080/16000870.2017.1330454
Title: Modelling mangrove propagule dispersal trajectories using high-resolution estimates of ocean surface winds and currents
Type: Journal Article
Publication: Biotropica
Author(s): Van der Stocken, Tom; Menemenlis, Dimitris
Year: 2017
Formatted Citation: Van der Stocken, T., and D. Menemenlis, 2017: Modelling mangrove propagule dispersal trajectories using high-resolution estimates of ocean surface winds and currents. Biotropica, 49(4), 472-481, doi:10.1111/btp.12440
Abstract: Mangrove forests are systems that provide ecosystem services and rely on floating propagules of which the dispersal trajectories are determined by ocean currents and winds. Quantitating connectivity of mangrove patches is an important conservation concern. Current estimates of connectivity, however, fail to integrate the link between ocean currents at different spatial scales and dispersal trajectories. Here, we use high-resolution estimates of ocean currents and surface winds from meteorological and oceanographic analyses, in conjunction with experimental data on propagule traits (e.g., density, size, and shape) and dispersal vector properties (e.g., strength and direction of water and wind currents). We incorporate these data in a dispersal model to illustrate the potential effect of wind on dispersal trajectories of hydrochorous propagules from different mangrove species. We focus on the Western Indian Ocean, including the Mozambique Channel, which has received much attention because of its reported oceanic complexity, to illustrate the effect of oceanic features such as eddy currents and tides. In spite of the complex pattern of ocean surface currents and winds, some propagules are able to cross the Mozambique Channel. Eddy currents and tides may delay arrival at a suitable site. Experimentally demonstrated differences in wind sensitivity among propagule types were shown to affect the probability of departure and the shape of dispersal trajectories. The model could be used to reconstruct current fluxes of mangrove propagules that may help explain past and current distributions of mangrove forests and assess the potential for natural expansion of these forests.
Keywords: Mozambique Channel, Western Indian Ocean, connectivity, eddy currents, long distance dispersal, tidal motion
Wolfe, Christopher L.; Cessi, Paola; Cornuelle, Bruce D. (2017). An Intrinsic Mode of Interannual Variability in the Indian Ocean, Journal of Physical Oceanography, 3 (47), 701-719, 10.1175/JPO-D-16-0177.1.
Title: An Intrinsic Mode of Interannual Variability in the Indian Ocean
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Wolfe, Christopher L.; Cessi, Paola; Cornuelle, Bruce D.
Year: 2017
Formatted Citation: Wolfe, C. L., P. Cessi, and B. D. Cornuelle, 2017: An Intrinsic Mode of Interannual Variability in the Indian Ocean. Journal of Physical Oceanography, 47(3), 701-719, doi:10.1175/JPO-D-16-0177.1
Abstract: An intrinsic mode of self-sustained, interannual variability is identified in a coarse-resolution ocean model forced by an annually repeating atmospheric state. The variability has maximum loading in the Indian Ocean, with a significant projection into the South Atlantic Ocean. It is argued that this intrinsic mode is caused by baroclinic instability of the model's Leeuwin Current, which radiates out to the tropical Indian and South Atlantic Oceans as long Rossby waves at a period of 4 yr. This previously undescribed mode has a remarkably narrowband time series. However, the variability is not synchronized with the annual cycle; the phase of the oscillation varies chaotically on decadal time scales. The presence of this internal mode reduces the predictability of the ocean circulation by obscuring the response to forcing or initial condition perturbations. The signature of this mode can be seen in higher-resolution global ocean models driven by high-frequency atmospheric forcing, but altimeter and assimilation analyses do not show obvious signatures of such a mode, perhaps because of insufficient duration.
Yang, Yang; San Liang, X; Qiu, Bo; Chen, Shuiming (2017). On the Decadal Variability of the Eddy Kinetic Energy in the Kuroshio Extension, Journal of Physical Oceanography, 5 (47), 1169-1187, 10.1175/JPO-D-16-0201.1.
Title: On the Decadal Variability of the Eddy Kinetic Energy in the Kuroshio Extension
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Yang, Yang; San Liang, X; Qiu, Bo; Chen, Shuiming
Year: 2017
Formatted Citation: Yang, Y., X. San Liang, B. Qiu, and S. Chen, 2017: On the Decadal Variability of the Eddy Kinetic Energy in the Kuroshio Extension. Journal of Physical Oceanography, 47(5), 1169-1187, doi:10.1175/JPO-D-16-0201.1
Abstract: Previous studies have found that the decadal variability of eddy kinetic energy (EKE) in the upstream Kuroshio Extension is negatively correlated with the jet strength, which seems counterintuitive at first glance because linear stability analysis usually suggests that a stronger jet would favor baroclinic instability and thus lead to stronger eddy activities. Using a time-varying energetics diagnostic methodology, namely, the localized multiscale energy and vorticity analysis (MS-EVA), and the MS-EVA-based nonlinear instability theory, this study investigates the physical mechanism responsible for such variations with the state estimate from the Estimating the Circulation and Climate of the Ocean (ECCO), Phase II. For the first time, it is found that the decadal modulation of EKE is mainly controlled by the barotropic instability of the background flow. During the high-EKE state, violent meanderings efficiently induce strong barotropic energy transfer from mean kinetic energy (MKE) to EKE despite the rather weak jet strength. The reverse is true in the low-EKE state. Although the enhanced meander in the high-EKE state also transfers a significant portion of energy from mean available potential energy (MAPE) to eddy available potential energy (EAPE) through baroclinic instability, the EAPE is not efficiently converted to EKE as the two processes are not well correlated at low frequencies revealed in the time-varying energetics. The decadal modulation of barotropic instability is found to be in pace with the North Pacific Gyre Oscillation but with a time lag of approximately 2 years.
Formatted Citation: Chevallier, M. and Coauthors, 2017: Intercomparison of the Arctic sea ice cover in global ocean-sea ice reanalyses from the ORA-IP project. Climate Dynamics, 49(3), 1107-1136, doi:10.1007/s00382-016-2985-y
Abstract: Ocean-sea ice reanalyses are crucial for assessing the variability and recent trends in the Arctic sea ice cover. This is especially true for sea ice volume, as long-term and large scale sea ice thickness observations are inexistent. Results from the Ocean ReAnalyses Intercomparison Project (ORA-IP) are presented, with a focus on Arctic sea ice fields reconstructed by state-of-the-art global ocean reanalyses. Differences between the various reanalyses are explored in terms of the effects of data assimilation, model physics and atmospheric forcing on properties of the sea ice cover, including concentration, thickness, velocity and snow. Amongst the 14 reanalyses studied here, 9 assimilate sea ice concentration, and none assimilate sea ice thickness data. The comparison reveals an overall agreement in the reconstructed concentration fields, mainly because of the constraints in surface temperature imposed by direct assimilation of ocean observations, prescribed or assimilated atmospheric forcing and assimilation of sea ice concentration. However, some spread still exists amongst the reanalyses, due to a variety of factors. In particular, a large spread in sea ice thickness is found within the ensemble of reanalyses, partially caused by the biases inherited from their sea ice model components. Biases are also affected by the assimilation of sea ice concentration and the treatment of sea ice thickness in the data assimilation process. An important outcome of this study is that the spatial distribution of ice volume varies widely between products, with no reanalysis standing out as clearly superior as compared to altimetry estimates. The ice thickness from systems without assimilation of sea ice concentration is not worse than that from systems constrained with sea ice observations. An evaluation of the sea ice velocity fields reveals that ice drifts too fast in most systems. As an ensemble, the ORA-IP reanalyses capture trends in Arctic sea ice area and extent relatively well. However, the ensemble can not be used to get a robust estimate of recent trends in the Arctic sea ice volume. Biases in the reanalyses certainly impact the simulated air-sea fluxes in the polar regions, and questions the suitability of current sea ice reanalyses to initialize seasonal forecasts.
Kleinherenbrink, Marcel; Riva, Riccardo; Frederikse, Thomas; Merrifield, Mark; Wada, Yoshihide (2017). Trends and interannual variability of mass and steric sea level in the Tropical Asian Seas, Journal of Geophysical Research: Oceans, 8 (122), 6254-6276, 10.1002/2017JC012792.
Formatted Citation: Kleinherenbrink, M., R. Riva, T. Frederikse, M. Merrifield, and Y. Wada, 2017: Trends and interannual variability of mass and steric sea level in the Tropical Asian Seas. J. Geophys. Res. Ocean., 122(8), 6254-6276, doi:10.1002/2017JC012792
Title: Mechanisms underlying recent decadal changes in subpolar North Atlantic Ocean heat content
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Piecuch, Christopher G; Ponte, Rui M; Little, Christopher M; Buckley, Martha W; Fukumori, Ichiro
Year: 2017
Formatted Citation: Piecuch, C. G., R. M. Ponte, C. M. Little, M. W. Buckley, and I. Fukumori, 2017: Mechanisms underlying recent decadal changes in subpolar North Atlantic Ocean heat content. J. Geophys. Res. Ocean., 122(9), 7181-7197, doi:10.1002/2017JC012845
Abstract: The subpolar North Atlantic (SPNA) is subject to strong decadal variability, with implications for surface climate and its predictability. In 2004-2005, SPNA decadal upper ocean and sea-surface temperature trends reversed from warming during 1994-2004 to cooling over 2005-2015. This recent decadal trend reversal in SPNA ocean heat content (OHC) is studied using a physically consistent, observationally constrained global ocean state estimate covering 1992-2015. The estimate's physical consistency facilitates quantitative causal attribution of ocean variations. Closed heat budget diagnostics reveal that the SPNA OHC trend reversal is the result of heat advection by midlatitude ocean circulation. Kinematic decompositions reveal that changes in the deep and intermediate vertical overturning circulation cannot account for the trend reversal, but rather ocean heat transports by horizontal gyre circulations render the primary contributions. The shift in horizontal gyre advection reflects anomalous circulation acting on the mean temperature gradients. Maximum covariance analysis (MCA) reveals strong covariation between the anomalous horizontal gyre circulation and variations in the local wind stress curl, suggestive of a Sverdrup response. Results have implications for decadal predictability.
Keywords: 1616 Climate variability, 3305 Climate change and variability, 4513 Decadal ocean variability, 4532 General circulation, Atlantic multidecadal variability, Sverdrup balance, decadal variability, heat content, ocean state estimation, overturning circulation
Rosso, Isabella; Mazloff, Matthew R; Verdy, Ariane; Talley, Lynne D (2017). Space and time variability of the Southern Ocean carbon budget, Journal of Geophysical Research: Oceans, 9 (122), 7407-7432, 10.1002/2016JC012646.
Title: Space and time variability of the Southern Ocean carbon budget
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Rosso, Isabella; Mazloff, Matthew R; Verdy, Ariane; Talley, Lynne D
Year: 2017
Formatted Citation: Rosso, I., M. R. Mazloff, A. Verdy, and L. D. Talley, 2017: Space and time variability of the Southern Ocean carbon budget. J. Geophys. Res. Ocean., 122(9), 7407-7432, doi:10.1002/2016JC012646
Abstract: The upper ocean dissolved inorganic carbon (DIC) concentration is regulated by advective and diffusive transport divergence, biological processes, freshwater, and air-sea CO2 fluxes. The relative importance of these mechanisms in the Southern Ocean is uncertain, as year-round observations in this area have been limited. We use a novel physical-biogeochemical state estimate of the Southern Ocean to construct a closed DIC budget of the top 650 m and investigate the spatial and temporal variability of the different components of the carbon system. The dominant mechanisms of variability in upper ocean DIC depend on location and time and space scales considered. Advective transport is the most influential mechanism and governs the local DIC budget across the 10 day-5 year timescales analyzed. Diffusive effects are nearly negligible. The large-scale transport structure is primarily set by upwelling and downwelling, though both the lateral ageostrophic and geostrophic transports are significant. In the Antarctic Circumpolar Current, the carbon budget components are also influenced by the presence of topography and biological hot spots. In the subtropics, evaporation and air-sea CO2 flux primarily balances the sink due to biological production and advective transport. Finally, in the subpolar region sea ice processes, which change the seawater volume and thus the DIC concentration, compensate the large impact of the advective transport and modulate the timing of biological activity and air-sea CO2 flux.
Keywords: 4207 Arctic and Antarctic oceanography, 4255 Numerical modeling, 4805 Biogeochemical cycles, 4806 Carbon cycling, Southern Ocean, and modeling, carbon budget, processes, state estimate
Liang, Xinfeng; Spall, Michael; Wunsch, Carl (2017). Global Ocean Vertical Velocity From a Dynamically Consistent Ocean State Estimate, Journal of Geophysical Research: Oceans, 10 (122), 8208-8224, 10.1002/2017JC012985.
Title: Global Ocean Vertical Velocity From a Dynamically Consistent Ocean State Estimate
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Liang, Xinfeng; Spall, Michael; Wunsch, Carl
Year: 2017
Formatted Citation: Liang, X., M. Spall, and C. Wunsch, 2017: Global Ocean Vertical Velocity From a Dynamically Consistent Ocean State Estimate. J. Geophys. Res. Ocean., 122(10), 8208-8224, doi:10.1002/2017JC012985
Abstract: Estimates of the global ocean vertical velocities (Eulerian, eddy-induced, and residual) from a dynamically consistent and data-constrained ocean state estimate are presented and analyzed. Conventional patterns of vertical velocity, Ekman pumping, appear in the upper ocean, with topographic dominance at depth. Intense and vertically coherent upwelling and downwelling occur in the Southern Ocean, which are likely due to the interaction of the Antarctic Circumpolar Current and large-scale topographic features and are generally canceled out in the conventional zonally averaged results. These "elevators" at high latitudes connect the upper to the deep and abyssal oceans and working together with isopycnal mixing are likely a mechanism, in addition to the formation of deep and abyssal waters, for fast responses of the deep and abyssal oceans to the changing climate. Also, Eulerian and parameterized eddy-induced components are of opposite signs in numerous regions around the global ocean, particularly in the ocean interior away from surface and bottom. Nevertheless, residual vertical velocity is primarily determined by the Eulerian component, and related to winds and large-scale topographic features. The current estimates of vertical velocities can serve as a useful reference for investigating the vertical exchange of ocean properties and tracers, and its complex spatial structure ultimately permits regional tests of basic oceanographic concepts such as Sverdrup balance and coastal upwelling/downwelling.
Keywords: 4220 Coral reef systems, 4260 Ocean data assimilation and reanalysis, 4279 Upwelling and convergences, 4532 General circulation, Southern Ocean, climate change, ocean state estimate, vertical exchange, vertical transport, vertical velocity
Title: Ocean heat content variability and change in an ensemble of ocean reanalyses
Type: Journal Article
Publication: Climate Dynamics
Author(s): Palmer, M. D.; Roberts, C. D.; Balmaseda, M.; Chang, Y.-S.; Chepurin, G.; Ferry, N.; Fujii, Y.; Good, S. A.; Guinehut, S.; Haines, K.; Hernandez, F.; Köhl, A.; Lee, T.; Martin, M. J.; Masina, S.; Masuda, S.; Peterson, K. A.; Storto, A.; Toyoda, T.; Valdivieso, M.; Vernieres, G.; Wang, O.; Xue, Y.
Year: 2017
Formatted Citation: Palmer, M. D. and Coauthors, 2017: Ocean heat content variability and change in an ensemble of ocean reanalyses. Climate Dynamics, 49(3), 909-930, doi:10.1007/s00382-015-2801-0
Davis, James; Vinogradova, Nadya (2017). Causes of accelerating sea level on the East Coast of North America, Geophysical Research Letters (44), 10.1002/2017GL072845.
Title: Causes of accelerating sea level on the East Coast of North America
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Davis, James; Vinogradova, Nadya
Year: 2017
Formatted Citation: Davis, J., and N. Vinogradova, 2017: Causes of accelerating sea level on the East Coast of North America. Geophys. Res. Lett., 44, doi:10.1002/2017GL072845
Abstract: The tide-gauge record from the North American East Coast reveals significant accelerations in sea level starting in the late twentieth century. The estimated post-1990 accelerations range from near zero to ∼0.3 mm yr-2. We find that the observed sea level acceleration is well modeled using several processes: mass change in Greenland and Antarctica as measured by the Gravity Recovery and Climate Experiment satellites; ocean dynamic and steric variability provided by the GECCO2 ocean synthesis; and the inverted barometer effect. However, to achieve this fit requires estimation of an admittance for the dynamical and steric contribution, possibly due to the coarse resolution of this analysis or to simplifications associated with parameterization of bottom friction in the shallow coastal areas. The acceleration from ice loss alone is equivalent to a regional sea level rise in one century of 0.2 m in the north and 0.75 m in the south of this region.
Qiu, Bo; Chen, Shuiming; Schneider, Niklas (2017). Dynamical Links between the Decadal Variability of the Oyashio and Kuroshio Extensions, Journal of Climate, 23 (30), 9591-9605, 10.1175/jcli-d-17-0397.1.
Formatted Citation: Qiu, B., S. Chen, and N. Schneider, 2017: Dynamical Links between the Decadal Variability of the Oyashio and Kuroshio Extensions. J. Clim., 30(23), 9591-9605, doi:10.1175/jcli-d-17-0397.1
Abstract: Rather than a single and continuous boundary current outflow, long-term satellite observations reveal that the Oyashio Extension (OE) in the North Pacific Subarctic Gyre comprises two independent, northeast-southwest-slanted front systems. With a mean latitude along 40°N, the western OE front exists primarily west of 153°E and is a continuation of the subarctic gyre western boundary current. The eastern OE front, also appearing along 40°N, is located between 153° and 170°E, whose entity is disconnected from its western counterpart. During 1982-2016, both of the OE fronts exhibit prominent decadal fluctuations, although their signals show little contemporaneous correlation. An upper-ocean temperature budget analysis based on the Estimating the Circulation and Climate of the Ocean, phase II (ECCO2), state estimate reveals that the advective temperature flux convergence plays a critical role in determining the low-frequency temperature changes relating to the OE fronts. Specifically, the western OE front variability is controlled by the decadal mesoscale eddy modulations in the upstream Kuroshio Extension (KE). An enhanced eddy activity increases the poleward heat transport and works to strengthen the western OE front. The eastern OE front variability, on the other hand, is dictated by both the meridional shift of the KE position and the circulation intensity change immediately north of the eastern OE. Different baroclinic adjustment speeds for the KE and OE are found to cause the in-phase changes between these latter two processes. Lack of contemporaneous correlation between the decadal western and eastern OE variability is found to be related to the interaction of the meridionally migrating KE jet with the Shatsky Rise near 159°E.
Evans, Dafydd Gwyn; Toole, John; Forget, Gael; Zika, Jan D; Garabato, Alberto C Naveira; Nurser, A J George; Yu, Lisan (2017). Recent Wind-Driven Variability in Atlantic Water Mass Distribution and Meridional Overturning Circulation, Journal of Physical Oceanography, 3 (47), 633-647, 10.1175/jpo-d-16-0089.1.
Title: Recent Wind-Driven Variability in Atlantic Water Mass Distribution and Meridional Overturning Circulation
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Evans, Dafydd Gwyn; Toole, John; Forget, Gael; Zika, Jan D; Garabato, Alberto C Naveira; Nurser, A J George; Yu, Lisan
Year: 2017
Formatted Citation: Evans, D. G., J. Toole, G. Forget, J. D. Zika, A. C. N. Garabato, A. J. G. Nurser, and L. Yu, 2017: Recent Wind-Driven Variability in Atlantic Water Mass Distribution and Meridional Overturning Circulation. Journal of Physical Oceanography, 47(3), 633-647, doi:10.1175/jpo-d-16-0089.1
Abstract: Interannual variability in the volumetric water mass distribution within the North Atlantic Subtropical Gyre is described in relation to variability in the Atlantic meridional overturning circulation. The relative roles of diabatic and adiabatic processes in the volume and heat budgets of the subtropical gyre are investigated by projecting data into temperature coordinates as volumes of water using an Argo-based climatology and an ocean state estimate (ECCO version 4). This highlights that variations in the subtropical gyre volume budget are predominantly set by transport divergence in the gyre. A strong correlation between the volume anomaly due to transport divergence and the variability of both thermocline depth and Ekman pumping over the gyre suggests that wind-driven heave drives transport anomalies at the gyre boundaries. This wind-driven heaving contributes significantly to variations in the heat content of the gyre, as do anomalies in the air-sea fluxes. The analysis presented suggests that wind forcing plays an important role in driving interannual variability in the Atlantic meridional overturning circulation and that this variability can be unraveled from spatially distributed hydrographic observations using the framework presented here.
Keywords: Atmosphere-ocean interaction, Ekman pumping/transport, Inverse methods, North Atlantic Ocean, Ocean circulation, Water masses
Verdy, A; Mazloff, M R (2017). A data assimilating model for estimating Southern Ocean biogeochemistry, Journal of Geophysical Research: Oceans, 9 (122), 6968-6988, 10.1002/2016JC012650.
Title: A data assimilating model for estimating Southern Ocean biogeochemistry
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Verdy, A; Mazloff, M R
Year: 2017
Formatted Citation: Verdy, A., and M. R. Mazloff, 2017: A data assimilating model for estimating Southern Ocean biogeochemistry. J. Geophys. Res. Ocean., 122(9), 6968-6988, doi:10.1002/2016JC012650
Abstract: A Biogeochemical Southern Ocean State Estimate (B-SOSE) is introduced that includes carbon and oxygen fields as well as nutrient cycles. The state estimate is constrained with observations while maintaining closed budgets and obeying dynamical and thermodynamic balances. Observations from profiling floats, shipboard data, underway measurements, and satellites are used for assimilation. The years 2008-2012 are chosen due to the relative abundance of oxygen observations from Argo floats during this time. The skill of the state estimate at fitting the data is assessed. The agreement is best for fields that are constrained with the most observations, such as surface pCO2 in Drake Passage (44% of the variance captured) and oxygen profiles (over 60% of the variance captured at 200 and 1000 m). The validity of adjoint method optimization for coupled physical-biogeochemical state estimation is demonstrated with a series of gradient check experiments. The method is shown to be mature and ready to synthesize in situ biogeochemical observations as they become more available. Documenting the B-SOSE configuration and diagnosing the strengths and weaknesses of the solution informs usage of this product as both a climate baseline and as a way to test hypotheses. Transport of Intermediate Waters across 32°S supplies significant amounts of nitrate to the Atlantic Ocean (5.57 ± 2.94 Tmol yr−1) and Indian Ocean (5.09 ± 3.06 Tmol yr−1), but much less nitrate reaches the Pacific Ocean (1.78 ± 1.91 Tmol yr−1). Estimates of air-sea carbon dioxide fluxes south of 50°S suggest a mean uptake of 0.18 Pg C/yr for the time period analyzed.
Keywords: 0414 Biogeochemical cycles, 4260 Ocean data assimilation and reanalysis, 4806 Carbon cycling, Southern Ocean, and modeling, biogeochemistry, processes, state estimation
Formatted Citation: Storto, A. and Coauthors, 2017: Steric sea level variability (1993-2010) in an ensemble of ocean reanalyses and objective analyses. Climate Dynamics, 49(3), 709-729, doi:10.1007/s00382-015-2554-9
Abstract: Quantifying the effect of the seawater density changes on sea level variability is of crucial importance for climate change studies, as the sea level cumulative rise can be regarded as both an important climate change indicator and a possible danger for human activities in coastal areas. In this work, as part of the Ocean Reanalysis Intercomparison Project, the global and regional steric sea level changes are estimated and compared from an ensemble of 16 ocean reanalyses and 4 objective analyses. These estimates are initially compared with a satellite-derived (altimetry minus gravimetry) dataset for a short period (2003-2010). The ensemble mean exhibits a significant high correlation at both global and regional scale, and the ensemble of ocean reanalyses outperforms that of objective analyses, in particular in the Southern Ocean. The reanalysis ensemble mean thus represents a valuable tool for further analyses, although large uncertainties remain for the inter-annual trends. Within the extended intercomparison period that spans the altimetry era (1993-2010), we find that the ensemble of reanalyses and objective analyses are in good agreement, and both detect a trend of the global steric sea level of 1.0 and 1.1 ± 0.05 mm/year, respectively. However, the spread among the products of the halosteric component trend exceeds the mean trend itself, questioning the reliability of its estimate. This is related to the scarcity of salinity observations before the Argo era. Furthermore, the impact of deep ocean layers is non-negligible on the steric sea level variability (22 and 12 % for the layers below 700 and 1500 m of depth, respectively), although the small deep ocean trends are not significant with respect to the products spread.
Formatted Citation: Toyoda, T. and Coauthors, 2017: Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses. Climate Dynamics, 49(3), 891-907, doi:10.1007/s00382-015-2762-3
Abstract: The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948-2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected.
Wu, Quran; Zhang, Xuebin; Church, John A.; Hu, Jianyu (2017). Variability and change of sea level and its components in the Indo-Pacific region during the altimetry era, Journal of Geophysical Research: Oceans, 3 (122), 1862-1881, 10.1002/2016JC012345.
Title: Variability and change of sea level and its components in the Indo-Pacific region during the altimetry era
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Wu, Quran; Zhang, Xuebin; Church, John A.; Hu, Jianyu
Year: 2017
Formatted Citation: Wu, Q., X. Zhang, J. A. Church, and J. Hu, 2017: Variability and change of sea level and its components in the Indo-Pacific region during the altimetry era. J. Geophys. Res. Ocean., 122(3), 1862-1881, doi:10.1002/2016JC012345
Liang, Xinfeng; Piecuch, Christopher G; Ponte, Rui M; Forget, Gael; Wunsch, Carl; Heimbach, Patrick (2017). Change of the Global Ocean Vertical Heat Transport over 1993-2010, Journal of Climate, 14 (30), 5319-5327, 10.1175/jcli-d-16-0569.1.
Title: Change of the Global Ocean Vertical Heat Transport over 1993-2010
Type: Journal Article
Publication: Journal of Climate
Author(s): Liang, Xinfeng; Piecuch, Christopher G; Ponte, Rui M; Forget, Gael; Wunsch, Carl; Heimbach, Patrick
Year: 2017
Formatted Citation: Liang, X., C. G. Piecuch, R. M. Ponte, G. Forget, C. Wunsch, and P. Heimbach, 2017: Change of the Global Ocean Vertical Heat Transport over 1993-2010. J. Clim., 30(14), 5319-5327, doi:10.1175/jcli-d-16-0569.1
Abstract: A dynamically and data-consistent ocean state estimate during 1993-2010 is analyzed for bidecadal changes in the mechanisms of heat exchange between the upper and lower oceans. Many patterns of change are consistent with prior studies. However, at various levels above 1800 m the global integral of the change in ocean vertical heat flux involves the summation of positive and negative regional contributions and is not statistically significant. The nonsignificance of change in the global ocean vertical heat transport from an ocean state estimate that provides global coverage and regular sampling, spatially and temporally, raises the question of whether an adequate observational database exists to assess changes in the upper ocean heat content over the past few decades. Also, whereas the advective term largely determines the spatial pattern of the change in ocean vertical heat flux, its global integral is not significantly different from zero. In contrast, the diffusive term, although regionally weak except in high-latitude oceans, produces a statistically significant extra downward heat flux during the 2000s. This result suggests that besides ocean advection, ocean mixing processes, including isopycnal and diapycnal as well as convective mixing, are important for the decadal variation of the heat exchange between upper and deep oceans as well. Furthermore, the analyses herein indicate that focusing on any particular region in explaining changes of the global ocean heat content is misleading.
Keywords: Climate variability, Data assimilation, Decadal variability, Mixing, Ocean circulation
Wilson, Nat; Straneo, Fiammetta; Heimbach, Patrick (2017). Satellite-derived submarine melt rates and mass balance (2011-2015) for Greenland’s largest remaining ice tongues, The Cryosphere, 6 (11), 2773-2782, 10.5194/tc-11-2773-2017.
Title: Satellite-derived submarine melt rates and mass balance (2011-2015) for Greenland’s largest remaining ice tongues
Type: Journal Article
Publication: The Cryosphere
Author(s): Wilson, Nat; Straneo, Fiammetta; Heimbach, Patrick
Year: 2017
Formatted Citation: Wilson, N., F. Straneo, and P. Heimbach, 2017: Satellite-derived submarine melt rates and mass balance (2011-2015) for Greenland's largest remaining ice tongues. Cryosph., 11(6), 2773-2782, doi:10.5194/tc-11-2773-2017
Abstract: Ice-shelf-like floating extensions at the termini of Greenland glaciers are undergoing rapid changes with po- tential implications for the stability of upstream glaciers and the ice sheet as a whole. While submarine melting is recog- nized as a major contributor to mass loss, the spatial distri- bution of submarine melting and its contribution to the to- tal mass balance of these floating extensions is incompletely known and understood. Here, we use high-resolution World- View satellite imagery collected between 2011 and 2015 to infer the magnitude and spatial variability of melt rates un- der Greenland's largest remaining ice tongues - Nioghalvf- jerdsbræ (79 North Glacier, 79N), Ryder Glacier (RG), and Petermann Glacier (PG). Submarine melt rates under the ice tongues vary considerably, exceeding 50ma−1 near the grounding zone and decaying rapidly downstream. Channels, likely originating from upstream subglacial channels, give rise to large melt variations across the ice tongues. We com- pare the total melt rates to the influx of ice to the ice tongue to assess their contribution to the current mass balance. At Petermann Glacier and Ryder Glacier, we find that the com- bined submarine and aerial melt approximately balances the ice flux from the grounded ice sheet. At Nioghalvfjerdsbræ the total melt flux (14.2 ± 0.96 km3 a−1 w.e., water equiva- lent) exceeds the inflow of ice (10.2 ± 0.59 km3 a−1 w.e.), in- dicating present thinning of the ice tongue.
Melzer, B A; Subrahmanyam, B (2017). Evaluation of GRACE Mascon Gravity Solution in Relation to Interannual Oceanic Water Mass Variations, IEEE Transactions on Geoscience and Remote Sensing, 2 (55), 907-914, 10.1109/TGRS.2016.2616760.
Title: Evaluation of GRACE Mascon Gravity Solution in Relation to Interannual Oceanic Water Mass Variations
Type: Journal Article
Publication: IEEE Transactions on Geoscience and Remote Sensing
Author(s): Melzer, B A; Subrahmanyam, B
Year: 2017
Formatted Citation: Melzer, B. A., and B. Subrahmanyam, 2017: Evaluation of GRACE Mascon Gravity Solution in Relation to Interannual Oceanic Water Mass Variations. IEEE Transactions on Geoscience and Remote Sensing, 55(2), 907-914, doi:10.1109/TGRS.2016.2616760
Abstract: With evidence of an accelerated water cycle over the past few decades, we make inferences on the spatial variability of interannual evaporation and precipitation patterns from 2003 to 2014 gravity anomalies, using the Gravity Recovery and Climate Experiment (GRACE) satellite mascon data set. Comparison of the mascon solution with an ensemble harmonic solution is conducted, along with validation over the oceans via sea surface height from multimission altimetry minus Argo floats data/GECCO2 [the GECCO2 ocean synthesis is the German contribution to Estimating the Circulation and Climate of the Ocean project (www.ecco-group.org)] steric sea level. The mascon solution was consistently more accurate than its spherical harmonic counterpart across large spatial and temporal scales, due mainly to the inherent smoothing from the mascon cells. Comparison of GRACE with both GECCO2 + altimetry and Argo + altimetry mass estimates revealed an offset in phase with regard to the annual cycle, but yielded an rmse of only 5.6 mm in the interannual signal after phase correction. This paper furthers evidence of an accelerated water cycle at a rate of 1.5% ± 1.1% at low latitudes, and provides a means of validation for oceanic freshwater budget studies based on salinity measurements.
Keywords: AD 2003 to 2014, Altimetry, Argo floats data, GECCO2, GRACE mascon gravity solution, GRACE satellite mascon data set, Gravity, Gravity Recovery and Climate Experiment, Gravity Recovery and Climate Experiment (GRACE), Harmonic analysis, Market research, Salinity (geophysical), Satellites, Sea level, accelerated water cycle, gravity, gravity anomaly, height measurement, interannual oceanic water mass variation, mascon cell, multimission altimetry, ocean mass, oceanic freshwater budget study, precipitation pattern, remote sensing, salinity (geophysical), salinity measurements, sea level, sea surface height, spatial interannual evaporation variability, steric sea level, water cycle
Formatted Citation: Toyoda, T. and Coauthors, 2017: Intercomparison and validation of the mixed layer depth fields of global ocean syntheses. Climate Dynamics, 49(3), 753-773, doi:10.1007/s00382-015-2637-7
Abstract: Intercomparison and evaluation of the global ocean surface mixed layer depth (MLD) fields estimated from a suite of major ocean syntheses are conducted. Compared with the reference MLDs calculated from individual profiles, MLDs calculated from monthly mean and gridded profiles show negative biases of 10-20 m in early spring related to the re-stratification process of relatively deep mixed layers. Vertical resolution of profiles also influences the MLD estimation. MLDs are underestimated by approximately 5-7 (14-16) m with the vertical resolution of 25 (50) m when the criterion of potential density exceeding the 10-m value by 0.03 kg m−3 is used for the MLD estimation. Using the larger criterion (0.125 kg m−3) generally reduces the underestimations. In addition, positive biases greater than 100 m are found in wintertime subpolar regions when MLD criteria based on temperature are used. Biases of the reanalyses are due to both model errors and errors related to differences between the assimilation methods. The result shows that these errors are partially cancelled out through the ensemble averaging. Moreover, the bias in the ensemble mean field of the reanalyses is smaller than in the observation-only analyses. This is largely attributed to comparably higher resolutions of the reanalyses. The robust reproduction of both the seasonal cycle and interannual variability by the ensemble mean of the reanalyses indicates a great potential of the ensemble mean MLD field for investigating and monitoring upper ocean processes.
Formatted Citation: Liu, W., S. Xie, Z. Liu, and J. Zhu, 2017: Overlooked possibility of a collapsed Atlantic Meridional Overturning Circulation in warming climate. Science Advances, 3(1), http://advances.sciencemag.org/content/3/1/e1601666.abstract
Abstract: Changes in the Atlantic Meridional Overturning Circulation (AMOC) are moderate in most climate model projections under increasing greenhouse gas forcing. This intermodel consensus may be an artifact of common model biases that favor a stable AMOC. Observationally based freshwater budget analyses suggest that the AMOC is in an unstable regime susceptible for large changes in response to perturbations. By correcting the model biases, we show that the AMOC collapses 300 years after the atmospheric CO2 concentration is abruptly doubled from the 1990 level. Compared to an uncorrected model, the AMOC collapse brings about large, markedly different climate responses: a prominent cooling over the northern North Atlantic and neighboring areas, sea ice increases over the Greenland-Iceland-Norwegian seas and to the south of Greenland, and a significant southward rain-belt migration over the tropical Atlantic. Our results highlight the need to develop dynamical metrics to constrain models and the importance of reducing model biases in long-term climate projection.
Title: Biogeochemical versus ecological consequences of modeled ocean physics
Type: Journal Article
Publication: Biogeosciences
Author(s): Clayton, Sophie; Dutkiewicz, Stephanie; Jahn, Oliver; Hill, Christopher; Heimbach, Patrick; Follows, Michael J.
Year: 2017
Formatted Citation: Clayton, S., S. Dutkiewicz, O. Jahn, C. Hill, P. Heimbach, and M. J. Follows, 2017: Biogeochemical versus ecological consequences of modeled ocean physics. Biogeosciences, 14(11), 2877-2889, doi:10.5194/bg-14-2877-2017
Abstract: We present a systematic study of the differences generated by coupling the same ecological-biogeochemical model to a 1°, coarse-resolution, and 1∕6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions might be more easily understood.
Other URLs: https://www.biogeosciences.net/14/2877/2017/
Meyssignac, B; Piecuch, C G; Merchant, C J; Racault, M.-F.; Palanisamy, H; MacIntosh, C; Sathyendranath, S; Brewin, R (2017). Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993-2011, Surveys in Geophysics, 1 (38), 1-29, 10.1007/s10712-016-9383-1.
Title: Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993-2011
Type: Journal Article
Publication: Surveys in Geophysics
Author(s): Meyssignac, B; Piecuch, C G; Merchant, C J; Racault, M.-F.; Palanisamy, H; MacIntosh, C; Sathyendranath, S; Brewin, R
Year: 2017
Formatted Citation: Meyssignac, B., C. G. Piecuch, C. J. Merchant, M. Racault, H. Palanisamy, C. MacIntosh, S. Sathyendranath, and R. Brewin, 2017: Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993-2011. Surveys in Geophysics, 38(1), 1-29, doi:10.1007/s10712-016-9383-1
Abstract: We analyse the regional variability in observed sea surface height (SSH), sea surface temperature (SST) and ocean colour (OC) from the ESA Climate Change Initiative datasets over the period 1993-2011. The analysis focuses on the signature of the ocean large-scale climate fluctuations driven by the atmospheric forcing and do not address the mesoscale variability. We use the ECCO version 4 ocean reanalysis to unravel the role of ocean transport and surface buoyancy fluxes in the observed SSH, SST and OC variability. We show that the SSH regional variability is dominated by the steric effect (except at high latitude) and is mainly shaped by ocean heat transport divergences with some contributions from the surface heat fluxes forcing that can be significant regionally (confirming earlier results). This is in contrast with the SST regional variability, which is the result of the compensation of surface heat fluxes by ocean heat transport in the mixed layer and arises from small departures around this background balance. Bringing together the results of SSH and SST analyses, we show that SSH and SST bear some common variability. This is because both SSH and SST variability show significant contributions from the surface heat fluxes forcing. It is evidenced by the high correlation between SST and buoyancy-forced SSH almost everywhere in the ocean except at high latitude. OC, which is determined by phytoplankton biomass, is governed by the availability of light and nutrients that essentially depend on climate fluctuations. For this reason, OC shows significant correlation with SST and SSH. We show that the correlation with SST displays the same pattern as the correlation with SSH with a negative correlation in the tropics and subtropics and a positive correlation at high latitude. We discuss the reasons for this pattern.
Other URLs: http://dx.doi.org/10.1007/s10712-016-9383-1
Chin, Toshio Michael; Vazquez-Cuervo, Jorge; Armstrong, Edward M. (2017). A multi-scale high-resolution analysis of global sea surface temperature, Remote Sensing of Environment (200), 154-169, 10.1016/j.rse.2017.07.029.
Title: A multi-scale high-resolution analysis of global sea surface temperature
Type: Journal Article
Publication: Remote Sensing of Environment
Author(s): Chin, Toshio Michael; Vazquez-Cuervo, Jorge; Armstrong, Edward M.
Year: 2017
Formatted Citation: Chin, T. M., J. Vazquez-Cuervo, and E. M. Armstrong, 2017: A multi-scale high-resolution analysis of global sea surface temperature. Remote Sensing of Environment, 200, 154-169, doi:10.1016/j.rse.2017.07.029
Title: From Topographic Internal Gravity Waves to Turbulence
Type: Journal Article
Publication: Annual Review of Fluid Mechanics
Author(s): Sarkar, S.; Scotti, A.
Year: 2017
Formatted Citation: Sarkar, S., and A. Scotti, 2017: From Topographic Internal Gravity Waves to Turbulence. Annual Review of Fluid Mechanics, 49(1), 195-220, doi:10.1146/annurev-fluid-010816-060013
Seroussi, Hélène; Nakayama, Y.; Larour, E.; Menemenlis, Dimitris; Morlighem, M.; Rignot, E.; Khazendar, A. (2017). Continued retreat of Thwaites Glacier, West Antarctica, controlled by bed topography and ocean circulation, Geophysical Research Letters, 12 (44), 6191-6199, 10.1002/2017GL072910.
Title: Continued retreat of Thwaites Glacier, West Antarctica, controlled by bed topography and ocean circulation
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Seroussi, Hélène; Nakayama, Y.; Larour, E.; Menemenlis, Dimitris; Morlighem, M.; Rignot, E.; Khazendar, A.
Year: 2017
Formatted Citation: Seroussi, H., Y. Nakayama, E. Larour, D. Menemenlis, M. Morlighem, E. Rignot, and A. Khazendar, 2017: Continued retreat of Thwaites Glacier, West Antarctica, controlled by bed topography and ocean circulation. Geophys. Res. Lett., 44(12), 6191-6199, doi:10.1002/2017GL072910
Title: Contrasting carbon cycle responses of the tropical continents to the 2015-2016 El Niño
Type: Journal Article
Publication: Science
Author(s): Liu, Junjie; Bowman, Kevin W.; Schimel, David S.; Parazoo, Nicolas C.; Jiang, Zhe; Lee, Meemong; Bloom, A. Anthony; Wunch, Debra; Frankenberg, Christian; Sun, Ying; O'Dell, Christopher W.; Gurney, Kevin R.; Menemenlis, Dimitris; Gierach, Michelle; Crisp, David; Eldering, Annmarie
Year: 2017
Formatted Citation: Liu, J. and Coauthors, 2017: Contrasting carbon cycle responses of the tropical continents to the 2015-2016 El Niño. Science, 358(6360), eaam5690, doi:10.1126/science.aam5690
Other URLs: http://science.sciencemag.org/content/358/6360/eaam5690
Santoso, Agus; Mcphaden, Michael J.; Cai, Wenju (2017). The Defining Characteristics of ENSO Extremes and the Strong 2015/2016 El Niño, Reviews of Geophysics, 4 (55), 1079-1129, 10.1002/2017RG000560.
Title: The Defining Characteristics of ENSO Extremes and the Strong 2015/2016 El Niño
Type: Journal Article
Publication: Reviews of Geophysics
Author(s): Santoso, Agus; Mcphaden, Michael J.; Cai, Wenju
Year: 2017
Formatted Citation: Santoso, A., M. J. Mcphaden, and W. Cai, 2017: The Defining Characteristics of ENSO Extremes and the Strong 2015/2016 El Niño. Reviews of Geophysics, 55(4), 1079-1129, doi:10.1002/2017RG000560
Other URLs: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017RG000560
Wagner, Till J. W.; Dell, Rebecca W.; Eisenman, Ian (2017). An Analytical Model of Iceberg Drift, Journal of Physical Oceanography, 7 (47), 1605-1616, 10.1175/JPO-D-16-0262.1.
Author(s): Wagner, Till J. W.; Dell, Rebecca W.; Eisenman, Ian
Year: 2017
Formatted Citation: Wagner, T. J. W., R. W. Dell, and I. Eisenman, 2017: An Analytical Model of Iceberg Drift. Journal of Physical Oceanography, 47(7), 1605-1616, doi:10.1175/JPO-D-16-0262.1
Blunden, Jessica; Arndt, Derek S. (2017). State of the Climate in 2016, Bulletin of the American Meteorological Society, 8 (98), Si-S280, 10.1175/2017BAMSStateoftheClimate.1.
Publication: Bulletin of the American Meteorological Society
Author(s): Blunden, Jessica; Arndt, Derek S.
Year: 2017
Formatted Citation: Blunden, J., and D. S. Arndt, 2017: State of the Climate in 2016. Bull. Am. Meteorol. Soc., 98(8), Si-S280, doi:10.1175/2017BAMSStateoftheClimate.1
Bigdeli, Arash; Loose, Brice; Nguyen, An T.; Cole, Sylvia T. (2017). Numerical investigation of the Arctic ice-ocean boundary layer and implications for air-sea gas fluxes, Ocean Science, 1 (13), 61-75, 10.5194/os-13-61-2017.
Title: Numerical investigation of the Arctic ice-ocean boundary layer and implications for air-sea gas fluxes
Type: Journal Article
Publication: Ocean Science
Author(s): Bigdeli, Arash; Loose, Brice; Nguyen, An T.; Cole, Sylvia T.
Year: 2017
Formatted Citation: Bigdeli, A., B. Loose, A. T. Nguyen, and S. T. Cole, 2017: Numerical investigation of the Arctic ice-ocean boundary layer and implications for air-sea gas fluxes. Ocean Science, 13(1), 61-75, doi:10.5194/os-13-61-2017
Abstract: In ice-covered regions it is challenging to determine constituent budgets - for heat and momentum, but also for biologically and climatically active gases like carbon dioxide and methane. The harsh environment and relative data scarcity make it difficult to characterize even the physical properties of the ocean surface. Here, we sought to evaluate if numerical model output helps us to better estimate the physical forcing that drives the air-sea gas exchange rate (k) in sea ice zones. We used the budget of radioactive 222Rn in the mixed layer to illustrate the effect that sea ice forcing has on gas budgets and air-sea gas exchange. Appropriate constraint of the 222Rn budget requires estimates of sea ice velocity, concentration, mixed-layer depth, and water velocities, as well as their evolution in time and space along the Lagrangian drift track of a mixed-layer water parcel. We used 36, 9 and 2km horizontal resolution of regional Massachusetts Institute of Technology general circulation model (MITgcm) configuration with fine vertical spacing to evaluate the capability of the model to reproduce these parameters. We then compared the model results to existing field data including satellite, moorings and ice-tethered profilers. We found that mode sea ice coverage agrees with satellite-derived observation 88 to 98% of the time when averaged over the Beaufort Gyre, and model sea ice speeds have 82% correlation with observations. The model demonstrated the capacity to capture the broad trends in the mixed layer, although with a significant bias. Model water velocities showed only 29% correlation with point-wise in situ data. This correlation remained low in all three model resolution simulations and we argued that is largely due to the quality of the input atmospheric forcing. Overall, we found that even the coarse-resolution model can make a modest contribution to gas exchange parameterization, by resolving the time variation of parameters that drive the 222Rn budget, including rate of mixed-layer change and sea ice forcings.
Title: Acoustic Tomography in the Canary Basin: Meddies and Tides
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Dushaw, Brian D.; Gaillard, Fabienne; Terre, Thierry
Year: 2017
Formatted Citation: Dushaw, B. D., F. Gaillard, and T. Terre, 2017: Acoustic Tomography in the Canary Basin: Meddies and Tides. J. Geophys. Res. Ocean., 122(11), 8983-9003, doi:10.1002/2017JC013356
Harrison, Daniel P. (2017). Global negative emissions capacity of ocean macronutrient fertilization, Environmental Research Letters, 3 (12), 035001, 10.1088/1748-9326/aa5ef5.
Title: Global negative emissions capacity of ocean macronutrient fertilization
Type: Journal Article
Publication: Environmental Research Letters
Author(s): Harrison, Daniel P.
Year: 2017
Formatted Citation: Harrison, D. P., 2017: Global negative emissions capacity of ocean macronutrient fertilization. Environmental Research Letters, 12(3), 035001, doi:10.1088/1748-9326/aa5ef5
Wagner, Till J.W.; Stern, Alon A.; Dell, Rebecca W.; Eisenman, Ian (2017). On the representation of capsizing in iceberg models, Ocean Modelling (117), 88-96, 10.1016/j.ocemod.2017.07.003.
Title: On the representation of capsizing in iceberg models
Type: Journal Article
Publication: Ocean Modelling
Author(s): Wagner, Till J.W.; Stern, Alon A.; Dell, Rebecca W.; Eisenman, Ian
Year: 2017
Formatted Citation: Wagner, T. J., A. A. Stern, R. W. Dell, and I. Eisenman, 2017: On the representation of capsizing in iceberg models. Ocean Modelling, 117, 88-96, doi:10.1016/j.ocemod.2017.07.003
Liu, Chengyan; Wang, Zhaomin; Li, Bingrui; Cheng, Chen; Xia, Ruibin (2017). On the response of subduction in the South Pacific to an intensification of westerlies and heat flux in an eddy permitting ocean model, Advances in Atmospheric Sciences, 4 (34), 521-531, 10.1007/s00376-016-6021-2.
Formatted Citation: Liu, C., Z. Wang, B. Li, C. Cheng, and R. Xia, 2017: On the response of subduction in the South Pacific to an intensification of westerlies and heat flux in an eddy permitting ocean model. Advances in Atmospheric Sciences, 34(4), 521-531, doi:10.1007/s00376-016-6021-2
Harrison, Daniel P.; Hinton, Michael G.; Kohin, Suzanne; Armstrong, Edward M.; Snyder, Stephanie; O'Brien, Frank; Kiefer, Dale K. (2017). The pelagic habitat analysis module for ecosystem-based fisheries science and management, Fisheries Oceanography, 3 (26), 316-335, 10.1111/fog.12194.
Title: The pelagic habitat analysis module for ecosystem-based fisheries science and management
Type: Journal Article
Publication: Fisheries Oceanography
Author(s): Harrison, Daniel P.; Hinton, Michael G.; Kohin, Suzanne; Armstrong, Edward M.; Snyder, Stephanie; O'Brien, Frank; Kiefer, Dale K.
Year: 2017
Formatted Citation: Harrison, D. P., M. G. Hinton, S. Kohin, E. M. Armstrong, S. Snyder, F. O'Brien, and D. K. Kiefer, 2017: The pelagic habitat analysis module for ecosystem-based fisheries science and management. Fisheries Oceanography, 26(3), 316-335, doi:10.1111/fog.12194
Wagner, Till J. W.; Eisenman, Ian (2017). How climate model biases skew the distribution of iceberg meltwater, Geophysical Research Letters, 8 (44), 3691-3699, 10.1002/2016GL071645.
Title: How climate model biases skew the distribution of iceberg meltwater
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Wagner, Till J. W.; Eisenman, Ian
Year: 2017
Formatted Citation: Wagner, T. J. W., and I. Eisenman, 2017: How climate model biases skew the distribution of iceberg meltwater. Geophys. Res. Lett., 44(8), 3691-3699, doi:10.1002/2016GL071645
Gregor, Luke; Kok, Schalk; Monteiro, Pedro M. S. (2017). Empirical methods for the estimation of Southern Ocean CO2: support vector and random forest regression, Biogeosciences, 23 (14), 5551-5569, 10.5194/bg-14-5551-2017.
Title: Empirical methods for the estimation of Southern Ocean CO2: support vector and random forest regression
Type: Journal Article
Publication: Biogeosciences
Author(s): Gregor, Luke; Kok, Schalk; Monteiro, Pedro M. S.
Year: 2017
Formatted Citation: Gregor, L., S. Kok, and P. M. S. Monteiro, 2017: Empirical methods for the estimation of Southern Ocean CO2: support vector and random forest regression. Biogeosciences, 14(23), 5551-5569, doi:10.5194/bg-14-5551-2017
Abstract: The Southern Ocean accounts for 40% of oceanic CO2 uptake, but the estimates are bound by large uncertainties due to a paucity in observations. Gap-filling empirical methods have been used to good effect to approximate pCO2 from satellite observable variables in other parts of the ocean, but many of these methods are not in agreement in the Southern Ocean. In this study we propose two additional methods that perform well in the Southern Ocean: support vector regression (SVR) and random forest regression (RFR). The methods are used to estimate ΔpCO2 in the Southern Ocean based on SOCAT v3, achieving similar trends to the SOM-FFN method by Landschützer et al. (2014). Results show that the SOM-FFN and RFR approaches have RMSEs of similar magnitude (14.84 and 16.45µatm, where 1atm = 101325Pa) where the SVR method has a larger RMSE (24.40µatm). However, the larger errors for SVR and RFR are, in part, due to an increase in coastal observations from SOCAT v2 to v3, where the SOM-FFN method used v2 data. The success of both SOM-FFN and RFR depends on the ability to adapt to different modes of variability. The SOM-FFN achieves this by having independent regression models for each cluster, while this flexibility is intrinsic to the RFR method. Analyses of the estimates shows that the SVR and RFR's respective sensitivity and robustness to outliers define the outcome significantly. Further analyses on the methods were performed by using a synthetic dataset to assess the following: which method (RFR or SVR) has the best performance? What is the effect of using time, latitude and longitude as proxy variables on ΔpCO2? What is the impact of the sampling bias in the SOCAT v3 dataset on the estimates? We find that while RFR is indeed better than SVR, the ensemble of the two methods outperforms either one, due to complementary strengths and weaknesses of the methods. Results also show that for the RFR and SVR implementations, it is better to include coordinates as proxy variables as RMSE scores are lowered and the phasing of the seasonal cycle is more accurate. Lastly, we show that there is only a weak bias due to undersampling. The synthetic data provide a useful framework to test methods in regions of sparse data coverage and show potential as a useful tool to evaluate methods in future studies.
Volkov, Denis L.; Lee, Sang-Ki; Landerer, Felix W.; Lumpkin, Rick (2017). Decade-long deep-ocean warming detected in the subtropical South Pacific, Geophysical Research Letters, 2 (44), 927-936, 10.1002/2016GL071661.
Title: Decade-long deep-ocean warming detected in the subtropical South Pacific
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Volkov, Denis L.; Lee, Sang-Ki; Landerer, Felix W.; Lumpkin, Rick
Year: 2017
Formatted Citation: Volkov, D. L., S. Lee, F. W. Landerer, and R. Lumpkin, 2017: Decade-long deep-ocean warming detected in the subtropical South Pacific. Geophys. Res. Lett., 44(2), 927-936, doi:10.1002/2016GL071661
Cougnon, E. A.; Galton-Fenzi, B. K.; Rintoul, S. R.; Legrésy, B.; Williams, G. D.; Fraser, A. D.; Hunter, J. R. (2017). Regional Changes in Icescape Impact Shelf Circulation and Basal Melting, Geophysical Research Letters, 22 (44), 11,519-11,527, 10.1002/2017GL074943.
Title: Regional Changes in Icescape Impact Shelf Circulation and Basal Melting
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Cougnon, E. A.; Galton-Fenzi, B. K.; Rintoul, S. R.; Legrésy, B.; Williams, G. D.; Fraser, A. D.; Hunter, J. R.
Year: 2017
Formatted Citation: Cougnon, E. A., B. K. Galton-Fenzi, S. R. Rintoul, B. Legrésy, G. D. Williams, A. D. Fraser, and J. R. Hunter, 2017: Regional Changes in Icescape Impact Shelf Circulation and Basal Melting. Geophys. Res. Lett., 44(22), 11,519-11,527, doi:10.1002/2017GL074943
Formatted Citation: Liu, C., Z. Wang, C. Cheng, R. Xia, B. Li, and Z. Xie, 2017: Modeling modified Circumpolar Deep Water intrusions onto the Prydz Bay continental shelf, East Antarctica. J. Geophys. Res. Ocean., 122(7), 5198-5217, doi:10.1002/2016JC012336
Author(s): Naughten, Kaitlin A.; Galton-Fenzi, Benjamin K.; Meissner, Katrin J.; England, Matthew H.; Brassington, Gary B.; Colberg, Frank; Hattermann, Tore; Debernard, Jens B.
Year: 2017
Formatted Citation: Naughten, K. A., B. K. Galton-Fenzi, K. J. Meissner, M. H. England, G. B. Brassington, F. Colberg, T. Hattermann, and J. B. Debernard, 2017: Spurious sea ice formation caused by oscillatory ocean tracer advection schemes. Ocean Modelling, 116, 108-117, doi:10.1016/j.ocemod.2017.06.010
Aguiar, Wilton; Mata, Mauricio M.; Kerr, Rodrigo (2017). On deep convection events and Antarctic Bottom Water formation in ocean reanalysis products, Ocean Science, 6 (13), 851-872, 10.5194/os-13-851-2017.
Title: On deep convection events and Antarctic Bottom Water formation in ocean reanalysis products
Type: Journal Article
Publication: Ocean Science
Author(s): Aguiar, Wilton; Mata, Mauricio M.; Kerr, Rodrigo
Year: 2017
Formatted Citation: Aguiar, W., M. M. Mata, and R. Kerr, 2017: On deep convection events and Antarctic Bottom Water formation in ocean reanalysis products. Ocean Science, 13(6), 851-872, doi:10.5194/os-13-851-2017
Abstract: Open ocean deep convection is a common source of error in the representation of Antarctic Bottom Water (AABW) formation in ocean general circulation models. Although those events are well described in non-assimilatory ocean simulations, the recent appearance of a massive open ocean polynya in the Estimating the Circulation and Climate of the Ocean Phase II reanalysis product (ECCO2) raises questions on which mechanisms are responsible for those spurious events and whether they are also present in other state-of-the-art assimilatory reanalysis products. To investigate this issue, we evaluate how three recently released high-resolution ocean reanalysis products form AABW in their simulations. We found that two of the products create AABW by open ocean deep convection events in the Weddell Sea that are triggered by the interaction of sea ice with the Warm Deep Water, which shows that the assimilation of sea ice is not enough to avoid the appearance of open ocean polynyas. The third reanalysis, My Ocean University Reading UR025.4, creates AABW using a rather dynamically accurate mechanism. The UR025.4 product depicts both continental shelf convection and the export of Dense Shelf Water to the open ocean. Although the accuracy of the AABW formation in this reanalysis product represents an advancement in the representation of the Southern Ocean dynamics, the differences between the real and simulated processes suggest that substantial improvements in the ocean reanalysis products are still needed to accurately represent AABW formation.
Wu, Yang; Wang, Zhaomin; Liu, Chengyan (2017). On the response of the Lorenz energy cycle for the Southern Ocean to intensified westerlies, Journal of Geophysical Research: Oceans, 3 (122), 2465-2493, 10.1002/2016JC012539.
Title: On the response of the Lorenz energy cycle for the Southern Ocean to intensified westerlies
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Wu, Yang; Wang, Zhaomin; Liu, Chengyan
Year: 2017
Formatted Citation: Wu, Y., Z. Wang, and C. Liu, 2017: On the response of the Lorenz energy cycle for the Southern Ocean to intensified westerlies. J. Geophys. Res. Ocean., 122(3), 2465-2493, doi:10.1002/2016JC012539
Malpress, Veda; Bestley, Sophie; Corney, Stuart; Welsford, Dirk; Labrousse, Sara; Sumner, Michael; Hindell, Mark (2017). Bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (Mirounga leonina) in Prydz Bay, East Antarctica, PLOS ONE, 9 (12), e0184536, 10.1371/journal.pone.0184536.
Title: Bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (Mirounga leonina) in Prydz Bay, East Antarctica
Formatted Citation: Malpress, V., S. Bestley, S. Corney, D. Welsford, S. Labrousse, M. Sumner, and M. Hindell, 2017: Bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (Mirounga leonina) in Prydz Bay, East Antarctica. PLOS ONE, 12(9), e0184536, doi:10.1371/journal.pone.0184536
Jia, Fan; Hu, Dunxin; Hu, Shijian; Feng, Junqiao (2017). Niño4 as a Key Region for the Interannual Variability of the Western Pacific Warm Pool, Journal of Geophysical Research: Oceans, 11 (122), 9299-9314, 10.1002/2017JC013208.
Formatted Citation: Jia, F., D. Hu, S. Hu, and J. Feng, 2017: Niño4 as a Key Region for the Interannual Variability of the Western Pacific Warm Pool. J. Geophys. Res. Ocean., 122(11), 9299-9314, doi:10.1002/2017JC013208
Wu, Yang; Zhai, Xiaoming; Wang, Zhaomin (2017). Decadal-Mean Impact of Including Ocean Surface Currents in Bulk Formulas on Surface Air-Sea Fluxes and Ocean General Circulation, Journal of Climate, 23 (30), 9511-9525, 10.1175/JCLI-D-17-0001.1.
Formatted Citation: Wu, Y., X. Zhai, and Z. Wang, 2017: Decadal-Mean Impact of Including Ocean Surface Currents in Bulk Formulas on Surface Air-Sea Fluxes and Ocean General Circulation. J. Clim., 30(23), 9511-9525, doi:10.1175/JCLI-D-17-0001.1
Formatted Citation: King, J., G. Spreen, S. Gerland, C. Haas, S. Hendricks, L. Kaleschke, and C. Wang, 2017: Sea-ice thickness from field measurements in the northwestern Barents Sea. J. Geophys. Res. Ocean., 122(2), 1497-1512, doi:10.1002/2016JC012199
Belonenko, T. V.; Bashmachnikov, I. L.; Koldunov, A. V.; Kuibin, P. A. (2017). On the vertical velocity component in the mesoscale Lofoten vortex of the Norwegian Sea, Izvestiya, Atmospheric and Oceanic Physics, 6 (53), 641-649, 10.1134/S0001433817060032.
Title: On the vertical velocity component in the mesoscale Lofoten vortex of the Norwegian Sea
Type: Journal Article
Publication: Izvestiya, Atmospheric and Oceanic Physics
Author(s): Belonenko, T. V.; Bashmachnikov, I. L.; Koldunov, A. V.; Kuibin, P. A.
Year: 2017
Formatted Citation: Belonenko, T. V., I. L. Bashmachnikov, A. V. Koldunov, and P. A. Kuibin, 2017: On the vertical velocity component in the mesoscale Lofoten vortex of the Norwegian Sea. Izvestiya, Atmospheric and Oceanic Physics, 53(6), 641-649, doi:10.1134/S0001433817060032
Dushaw, Brian D.; Sagen, Hanne (2017). The role of simulated small-scale ocean variability in inverse computations for ocean acoustic tomography, The Journal of the Acoustical Society of America, 6 (142), 3541-3552, 10.1121/1.5016816.
Title: The role of simulated small-scale ocean variability in inverse computations for ocean acoustic tomography
Type: Journal Article
Publication: The Journal of the Acoustical Society of America
Author(s): Dushaw, Brian D.; Sagen, Hanne
Year: 2017
Formatted Citation: Dushaw, B. D., and H. Sagen, 2017: The role of simulated small-scale ocean variability in inverse computations for ocean acoustic tomography. The Journal of the Acoustical Society of America, 142(6), 3541-3552, doi:10.1121/1.5016816
Title: Rapid drawdown of Antarctica’s Wordie Ice Shelf glaciers in response to ENSO/Southern Annular Mode-driven warming in the Southern Ocean
Type: Journal Article
Publication: Earth and Planetary Science Letters
Author(s): Walker, C.C.; Gardner, A.S.
Year: 2017
Formatted Citation: Walker, C., and A. Gardner, 2017: Rapid drawdown of Antarctica's Wordie Ice Shelf glaciers in response to ENSO/Southern Annular Mode-driven warming in the Southern Ocean. Earth and Planetary Science Letters, 476, 100-110, doi:10.1016/j.epsl.2017.08.005
Verdy, Ariane; Cornuelle, Bruce; Mazloff, Matthew R.; Rudnick, Daniel L. (2017). Estimation of the Tropical Pacific Ocean State 2010-13, Journal of Atmospheric and Oceanic Technology, 7 (34), 1501-1517, 10.1175/JTECH-D-16-0223.1.
Title: Estimation of the Tropical Pacific Ocean State 2010-13
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Verdy, Ariane; Cornuelle, Bruce; Mazloff, Matthew R.; Rudnick, Daniel L.
Year: 2017
Formatted Citation: Verdy, A., B. Cornuelle, M. R. Mazloff, and D. L. Rudnick, 2017: Estimation of the Tropical Pacific Ocean State 2010-13. Journal of Atmospheric and Oceanic Technology, 34(7), 1501-1517, doi:10.1175/JTECH-D-16-0223.1
Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen (2017). Small-scale open ocean currents have large effects on wind wave heights, Journal of Geophysical Research: Oceans, 6 (122), 4500-4517, 10.1002/2016JC012413.
Title: Small-scale open ocean currents have large effects on wind wave heights
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen
Year: 2017
Formatted Citation: Ardhuin, F., S. T. Gille, D. Menemenlis, C. B. Rocha, N. Rascle, B. Chapron, J. Gula, and J. Molemaker, 2017: Small-scale open ocean currents have large effects on wind wave heights. J. Geophys. Res. Ocean., 122(6), 4500-4517, doi:10.1002/2016JC012413
Formatted Citation: Cai, C., E. Rignot, D. Menemenlis, and Y. Nakayama, 2017: Observations and modeling of ocean-induced melt beneath Petermann Glacier Ice Shelf in northwestern Greenland. Geophys. Res. Lett., 44(16), 8396-8403, doi:10.1002/2017GL073711
Title: Sea Surface Height Signatures of Internal Gravity Waves
Type: Thesis
Publication:
Author(s): Savage, Anna
Year: 2017
Formatted Citation: Savage, A., 2017: Sea Surface Height Signatures of Internal Gravity Waves., 99 pp. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/138555/savagea_1.pdf?sequence=1&isAllowed=y.
Abstract: Sea surface height (SSH) is a fundamental variable in physical oceanography and is the key observable quantity in global satellite altimetry. SSH is a complicated man- ifestation of many oceanic processes, and, as such, exhibits variability over a wide range of space and time scales. It is well known that tides are of first order impor- tance in SSH, but SSH contributions outside of this narrow band are also of great interest. Satellite altimetry has become an invaluable tool in the study of the global ocean. However, the long repeat period (of order ten to 40 days) of altimeters implies that high-frequency motions will be aliased in altimeter records. In order to study the lower-frequency SSH variability, the aliased high-frequency variability must first be accurately removed. Some of these high-frequency motions, such as the stationary component of surface and internal tides, can be adequately removed even from aliased records, via harmonic analysis or response methods, as long as the signal-to-noise ra- tio is relatively high. However, the challenge of removing SSH signals associated with motions that are less predictable, for instance, the non-stationary component of the internal tides, or the internal gravy wave (IGW) continuum, is much greater. To quantify the magnitude of this challenge, high resolution global general circulation ocean models are used to simulate and study internal tides, the IGW continuum, and other contributions to sea surface variability. Using these models, we examine the space- and time-scales of SSH variability. For instance, we compute frequency- horizontal wavenumber (ω − K) spectral densities over a several oceanic regions that collectively represent different regimes of global ocean variability. These ω − K spec- tral densities show high energy along lines representing the linear dispersion relations predicted by the Sturm-Liouville problem for internal waves. In many oceanic re- gions, the high-frequency motions dominate the small-scale (high-wavenumber) SSH spectra. This has implications for upcoming wide-swath satellite altimeter missions, which will focus on high-wavenumber SSH spectra. In addition to quantifying the frequency-horizontal wavenumber spectral densities, we estimate the SSH variance in subtidal, tidal, and supertidal phenomena through the use of frequency spectral densities. This temporally driven approach allows us to create global maps of SSH variance in these frequency bands. The global band-integrated maps are further di- vided into steric and non-steric SSH components, which further helps to delineate different classes of oceanic motions. These global band-integrated maps provide both results consistent with previous studies (e.g., of subtidal steric SSH, dominated by mesoscale eddies and well-measured by current generation satellite altimeters), as well as unprecedented global maps of the non-stationary component of the internal tides and of the IGW continuum. As global general circulation ocean models have only begun to be able to partially resolve the IGW continuum, we believe that our estimate represents a lower bound of variance in the IGW continuum, and will likely increase with increased horizontal and vertical resolution of ocean models. Indeed, comparisons of the models used here with in-situ data strongly suggest that the mod- els used here underestimate the IGW continuum, while representing other motions with a higher accuracy.
Schwedes, Tobias; Ham, David A.; Funke, Simon W.; Piggott, Matthew D. (2017). Introduction to PDE-constrained optimisation, Mesh Dependence in PDE-Constrained Optimisation, 1-52, 10.1007/978-3-319-59483-5_1.
Title: Introduction to PDE-constrained optimisation
Type: Book Section
Publication: Mesh Dependence in PDE-Constrained Optimisation
Author(s): Schwedes, Tobias; Ham, David A.; Funke, Simon W.; Piggott, Matthew D.
Year: 2017
Formatted Citation: Schwedes, T., D. A. Ham, S. W. Funke, and M. D. Piggott, 2017: Introduction to PDE-constrained optimisation. Mesh Dependence in PDE-Constrained Optimisation, Springer International Publishing, 1-52, doi:10.1007/978-3-319-59483-5_1
Wang, Zhaomin; Wu, Yang; Lin, Xia; Liu, Chengyan; Xie, Zelin (2017). Impacts of open-ocean deep convection in the Weddell Sea on coastal and bottom water temperature, Climate Dynamics, 9-10 (48), 2967-2981, 10.1007/s00382-016-3244-y.
Formatted Citation: Wang, Z., Y. Wu, X. Lin, C. Liu, and Z. Xie, 2017: Impacts of open-ocean deep convection in the Weddell Sea on coastal and bottom water temperature. Climate Dynamics, 48(9-10), 2967-2981, doi:10.1007/s00382-016-3244-y
Title: Submesoscale Sea Ice-Ocean Interactions in Marginal Ice Zones
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Manucharyan, Georgy E.; Thompson, Andrew F.
Year: 2017
Formatted Citation: Manucharyan, G. E., and A. F. Thompson, 2017: Submesoscale Sea Ice-Ocean Interactions in Marginal Ice Zones. J. Geophys. Res. Ocean., 122(12), 9455-9475, doi:10.1002/2017JC012895
Title: Stochastic Subgrid-Scale Ocean Mixing: Impacts on Low-Frequency Variability
Type: Journal Article
Publication: Journal of Climate
Author(s): Juricke, Stephan; Palmer, Tim N.; Zanna, Laure
Year: 2017
Formatted Citation: Juricke, S., T. N. Palmer, and L. Zanna, 2017: Stochastic Subgrid-Scale Ocean Mixing: Impacts on Low-Frequency Variability. J. Clim., 30(13), 4997-5019, doi:10.1175/JCLI-D-16-0539.1
Parkinson, Samuel D.; Funke, Simon W.; Hill, Jon; Piggott, Matthew D.; Allison, Peter A. (2017). Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model, Geoscientific Model Development, 3 (10), 1051-1068, 10.5194/gmd-10-1051-2017.
Title: Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model
Type: Journal Article
Publication: Geoscientific Model Development
Author(s): Parkinson, Samuel D.; Funke, Simon W.; Hill, Jon; Piggott, Matthew D.; Allison, Peter A.
Year: 2017
Formatted Citation: Parkinson, S. D., S. W. Funke, J. Hill, M. D. Piggott, and P. A. Allison, 2017: Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model. Geoscientific Model Development, 10(3), 1051-1068, doi:10.5194/gmd-10-1051-2017
Abstract: Turbidity currents are one of the main drivers of sediment transport from the continental shelf to the deep ocean. The resulting sediment deposits can reach hundreds of kilometres into the ocean. Computer models that simulate turbidity currents and the resulting sediment deposit can help us to understand their general behaviour. However, in order to recreate real-world scenarios, the challenge is to find the turbidity current parameters that reproduce the observations of sediment deposits. This paper demonstrates a solution to the inverse sediment transportation problem: for a known sedimentary deposit, the developed model reconstructs details about the turbidity current that produced the deposit. The reconstruction is constrained here by a shallow water sediment-laden density current model, which is discretised by the finite-element method and an adaptive time-stepping scheme. The model is differentiated using the adjoint approach, and an efficient gradient-based optimisation method is applied to identify the turbidity parameters which minimise the misfit between the modelled and the observed field sediment deposits. The capabilities of this approach are demonstrated using measurements taken in the Miocene Marnoso-arenacea Formation (Italy). We find that whilst the model cannot match the deposit exactly due to limitations in the physical processes simulated, it provides valuable insights into the depositional processes and represents a significant advance in our toolset for interpreting turbidity current deposits.
Stepanov, Vladimir Nikolaevich (2017). The Atlantic meridional heat and volume transports from ocean models and observations, Works of Hydrometeorological Research Center of the Russian Federation, 364, 104-130.
Title: The Atlantic meridional heat and volume transports from ocean models and observations
Type: Journal Article
Publication: Works of Hydrometeorological Research Center of the Russian Federation
Author(s): Stepanov, Vladimir Nikolaevich
Year: 2017
Formatted Citation: Stepanov, V. N., 2017: The Atlantic meridional heat and volume transports from ocean models and observations. Works of Hydrometeorological Research Center of the Russian Federation(364), 104-130, http://method.meteorf.ru/publ/tr/tr364/stepan.pdf
Abstract: Atlantic meridional circulation (AMOC) plays a major role in moving heat around in the ocean, which significantly affects the Earth's climate on different time scales. In this paper an overview of the modelled and observations-derived estimates of the AMOC and the meridional heat transport (MHT) at 26.5° N, 41° N and 34° S over the 2004-2013 period is presented with emphasis on the model calculations obtained with a 1/16° eddy-resolving global model.The reasons of discrepancy between the model values of the AMOC and the MHT and the observations-derived estimates are analysed. The findings in this paper provide guidance in understanding the AMOC and MHT dissimilarities at these three latitudes between ocean models and observation-basedestimates.
Formatted Citation: Chalamalla, V. K., E. Santilli, A. Scotti, M. Jalali, and S. Sarkar, 2017: SOMAR-LES: A framework for multi-scale modeling of turbulent stratified oceanic flows. Ocean Modelling, 120, 101-119, doi:10.1016/j.ocemod.2017.11.003
Title: The conversion rate of lee waves and the energetics of internal tides
Type: Thesis
Publication:
Author(s): Han, Bing
Year: 2017
Formatted Citation: Han, B., 2017: The conversion rate of lee waves and the energetics of internal tides., 130 pp.
Abstract: Tides and geostrophic flows are two important energy sources for the mixing in the deep ocean. The global conversion rate of internal lee waves generated by geostrophic flows, the baroclinic tide generated by the barotropic tide over sinusoidal topography and the energy budgets of internal waves at the Luzon ridge calculated from both two-dimensional and three-dimensional simulations are investigated in this paper. It is aimed to give us a better understanding of the role of tides and geostrophic flows in ocean dynamics. This paper consists of four parts. Firstly, the conversion rate of internal lee waves generated by geostrophic flows is calculated based on linear theory. In order to get a more precise value, we use two methods to deal with the topographic spectrum. The single beam sounding depth data, global predicted abyssal hill rms heights, WOCE hydrographic atlas, velocity data from SODA and ECCO2, mean flow and eddy velocity from the global eddy-permitting STORM model in a 1° × 1° grid are used for the calculations. By using these data, we can not only compare with the results from different velocity and topography databases, but also get the difference between the conversion rate from the eddies and from the mean flow. The results show that the conversion rates calculated using SODA, ECCO2, mean flow and eddy velocity from the global eddy-permitting STORM model are between 0.03 and 0.23 TW, and the difference between the conversion rate from the eddies and from the mean flow is between 0.05 and 0.11 TW. Secondly, a series of experiments are set up to investigate the baroclinic tide generated by barotropic tide over sinusoidal topography. The baroclinic velocity fields generated are quite different between in subcritical cases and in supercritical cases. The effects of the height of the topography, the amplitude of the barotropic tidal velocity, the stratification and the width of the topography on the baroclinic tide generated are studied in this chapter. The results show that the energy flux is almost proportional to the square of the height of the topography and the square of the amplitude of the barotropic tide; the energy flux will be larger when the width of topography is smaller and the stratification is stronger; there is almost no energy flux generated in experiments with too weak stratification or too wide topogaphy. The results predicted by the linear theory agree well with the results calculated by C1 (energy flux) in most cases, and the results calculated by C2 (conversion rate) are larger than the results calculated by C1 in most cases (the definitions of C1 and C2 could be found in Chapter 3). Thirdly, two-dimensional MIT General Circulation Model (MITgcm) is used to simulate internal waves at the Luzon ridge. Here, the topography is represented by two ideal Gaussian hills. The baroclinic energy budget of internal waves is studied and the conversion rate is mainly balanced by the energy flux. The effects of the height of the west ridge, the distance between the two ridges and the amplitude of the barotropic tide on the energy flux and conversion rate are also investigated. It is found that as the height of the west ridge increases, the westward energy flux increases; the internal tides can be enhanced due to a suitable distance between the two ridges; the amplitude of the barotropic tide is one of the crucial factors to determine whether the internal solitary waves would be generated or not, furthermore, when the amplitude of the barotropic tide is larger, the speed of the internal solitary waves generated will be larger. Finally, three-dimensional simulations of internal tides at the Luzon ridge are shown. The MITgcm is used to study the M2 and K1 internal tides and the data from WOCE and SODA are used to give the stratification here. In this chapter, not only the barotropic energy budget and baroclinic energy budget but also the barotropic kinetic energy budget and baroclinic kinetic energy budget are analyzed. About 15.1 GW is transferred from the M2 barotropic tide to the baroclinic tide, which is about 88% of the barotropic input. The energy flux is about 4.5 GW, and the total dissipation is about 11.3 GW. The formula (Nycander, 2005) may underestimate the conversion rate at the Luzon ridge.
Xu, Houze (2017). Global unification problem of the height system, Acta Geodaetica et Cartographica Sinica, 8 (46), 939-944, 10.11947/j.AGCS.2017.20170406.
Title: Global unification problem of the height system
Type: Journal Article
Publication: Acta Geodaetica et Cartographica Sinica
Author(s): Xu, Houze
Year: 2017
Formatted Citation: Xu, H., 2017: Global unification problem of the height system. Acta Geodaetica et Cartographica Sinica, 46(8), 939-944, doi:10.11947/j.AGCS.2017.20170406
Abstract: Some fundamental problems on the establishment of the global unified height system, including the geometry and gravity definition of the normal height, the global unification of the regional height systems obtained from leveling measurements, and the determination of geoid potential W0 are discussed. The main conclusions are summarized:① The definition of normal height in the sense of geometry leveling and gravity theory is different, so that h-ζ≠HL, here h, ζ and HL are geodetic height, height anomaly and levelling height respectively. Instead of it, we found , in the mountain area, the last correction term have to be added. ② Based on the merging of GNSS/gravity/regional leveling, the regional leveling height can be transformed into a global relative unified height system, however the value of geoid potential W0 is still needed in order to establish an absolute height system. ③ W0 can be determinated from the modern geodetic techniques with a certain accuracy, but it is time variable, so that people may only define a global absolute unified height system in a fixed epoch. Some fundamental problems on the establishment of the global unified height system, including the geometry and gravity definition of the normal height, the global unification of the regional height systems obtained from leveling measurements, and the determination of geoid potential W0 are discussed. The main conclusions are summarized:① The definition of normal height in the sense of geometry leveling and gravity theory is different, so that h-ζ≠HL, here h, ζ and HL are geodetic height, height anomaly and levelling height respectively. Instead of it, we found , in the mountain area, the last correction term have to be added. ② Based on the merging of GNSS/gravity/regional leveling, the regional leveling height can be transformed into a global relative unified height system, however the value of geoid potential W0 is still needed in order to establish an absolute height system. ③ W0 can be determinated from the modern geodetic techniques with a certain accuracy, but it is time variable, so that people may only define a global absolute unified height system in a fixed epoch.
Ma, Qiang; Wang, Jianing; Wang, Fan (2017). Deep-layer circulations in Tropical Western Pacific Ocean based on six ocean models outputs, Oceanologia et Limnologia Sinica, 6 (48), 1302-1317, 10.11693/hyhz20170600159.
Title: Deep-layer circulations in Tropical Western Pacific Ocean based on six ocean models outputs
Type: Journal Article
Publication: Oceanologia et Limnologia Sinica
Author(s): Ma, Qiang; Wang, Jianing; Wang, Fan
Year: 2017
Formatted Citation: Ma, Q., J. Wang, and F. Wang, 2017: Deep-layer circulations in Tropical Western Pacific Ocean based on six ocean models outputs. Oceanologia et Limnologia Sinica, 48(6), 1302-1317, doi:10.11693/hyhz20170600159
Abstract: We conducted a preliminary analysis on deep-layer circulation in the tropical western Pacific using six ocean models outputs. In comparison with WOA13, the HYCOM's deep temperature deviation at 3000 m is mainly positive, while other five models' are negative. The deep temperature deviations increase with depth. The deep salinity deviations of HYCOM and OFES are mainly positive, while other models' are mainly negative. Both the temporal trends of mean temperature and salinity deviations are different from the observations. The currents between 1000 and 3000m are dominated by alternating westward and eastward zonal jets. The zonal velocity decreases quickly below 3000m, and the circulations are separated by different basins between 3000 and 5000m, but the seawater exchange can take place through deep-layer passages among basins. The transport in deep-layer passages shows seasonal variability; moreover, the direction of current in some deep layers could be opposite in different seasons. The pattern of circulation is controlled by potential vorticity constraint equation, and thus also shows seasonal variation, indicating temporal difference in the form of major rotations in these basins. In addition, we discussed the impacts of T/S initial value, tide, and other factors on the deep circulations, and proposed suggestions for future improvement in the modeling.
Keywords:
ECCO Products Used: ECCO2
URL:
Other URLs:
Fukumori, Ichiro; Wang, Ou; Fenty, Ian; Forget, Gael; Heimbach, Patrick; Ponte, Rui M. (2017). ECCO Version 4 Release 3.
Formatted Citation: Fukumori, I., O. Wang, I. Fenty, G. Forget, P. Heimbach, and R. M. Ponte, 2017: ECCO Version 4 Release 3., 10 pp. doi:1721.1/110380.
Abstract: This note provides a brief synopsis of ECCO Version 4 Release 3, an updated edition to the global ocean state estimate described by Forget et al. (2015b, 2016), covering the period 1992-2015.
Schwab, Julia Maria (2017). Sediment dynamic, slope instability and potential tsunami hazard at the outer Thai shelf margin, Mergui Ridge, Andaman Sea.
Title: Sediment dynamic, slope instability and potential tsunami hazard at the outer Thai shelf margin, Mergui Ridge, Andaman Sea
Type: Thesis
Publication:
Author(s): Schwab, Julia Maria
Year: 2017
Formatted Citation: Schwab, J. M., 2017: Sediment dynamic, slope instability and potential tsunami hazard at the outer Thai shelf margin, Mergui Ridge, Andaman Sea., 137 pp.
Abstract: The Thai Andaman Sea coast, located in the vicinity of the Sunda Trench, has been repeatedly struck by tsunamis, one of them being the catastrophic and highly destructive 2004 Indian Ocean Tsunami, which was caused by an extreme earthquake at the Sunda Trench. More than 227000 people lost their lives during this catastrophe, 8200 of them in Thailand alone. Based on tsunami event layers retrieved at the Thai coast, the geological record shows that this was not the first tsunami that hit the area, and possible predecessors to the 2004 Tsunami have been identified in the geological record for the last two millennia. Most of the tsunamis worldwide are of tectonic origin, but it is well known, that earthquakes are not the only source for tsunamis. Submarine landslides can cause destructive tsunamis as well. Submarine landslides occur when a slope becomes unstable and fails. The stability of a slope depends largely on the sedimentary conditions, as these conditions govern the properties and the morphology of the sedimentary deposits. Thereby they dictate, whether failure preconditioning factors, such as rapid sedimentation, overpressure buildup or the presence of weak layers are developed. In order to assess the tsunami potential that may arise from a specific slope it is hence crucial to know the sedimentary processes and conditions that shape a margin. Moreover, it is important to know the failure history in order to estimate the frequency of failures and their dimensions. All this information may also help to assess the potential for future failures and for landslide tsunamis. The outer Thai shelf margin in the Andaman Sea has previously not been investigated in detail with respect to sediment dynamics and associated slope stability. Therefore, it was unknown so far, whether submarine mass wasting at this margin does occur and whether it may add to the tsunami hazard potential for the adjacent coasts. In order to examine the sedimentary development of this slope and in order to evaluate the state of the slope with respect to its stability and tsunami potential a new multibeam bathymetry and high resolution 2D multichannel reflection seismic data set was acquired during three subsequent research cruises (MASS I, MASS II and MASS III) in 2006, 2007 and 2011 from the Mergui Ridge area at the Thai outer shelf approximately 250km west off Phuket. The analysis of the newly acquired data shows that the Mergui Ridge, an area of low sedimentary input, is today shaped by bottom currents. This can be concluded from the presence of drift deposits adjacent to areas of low sedimentation or erosion of old sediments. Along-slope currents, fluctuating with the monsoon seasons and potentially also internal waves may be responsible for shaping the margin today. After a phase of uplift and subaerial exposure at the end of the Late Miocene, marked by a pronounced erosive unconformity, the Mergui Ridge shelf area subsided in the Pliocene to its recent position in up to 800m water depth. Tectonic deformation today is ongoing but on a smaller scale than in the past. This geological development is reflected in the older sedimentary deposits present in the Mergui Ridge area. This led to the deposition of a sedimentary unit characterized by indicators of local erosion when the ridge was in shallow water. Today a thin drape of undisturbed sediments partially covers these older sediments. Within the sediments of the Mergui Ridge area, seventeen mass transport deposits have been identified. Most of these deposits occur within drift deposits. Their presence shows that the slope has been unstable and failures have taken place repeatedly. The presence of fluids, instability of drift deposits and ongoing tectonic activity are considered as most important preconditioning factors; this setting may lead to failures in the future. Based on their mostly relative small dimension with volumes between approximately 0.3 and 14km3 , and the large water depth where the failures occur, it is unlikely for most of these failures to have been tsunamigenic, but triggering of tsunamis by such failures cannot be excluded. Based on the thickness of hemipelagic layers between events, the recurrence of these failures seems to be long, especially compared to the recurrence of tectonic tsunamis. A simple numerical modeling of landslide tsunami propagation and estimation of run up heighs based on geometrical parameters of the previously identified mass transport deposits of up to between 1.0 and 25.8m shows that landslides in the area may produce tsunamis. However, modeled tsunamis represent worst case scenarios and wave heights may be overestimated in the simple model.
Other URLs: https://macau.uni-kiel.de/receive/dissertation_diss_00022126?lang=en
Vondrák, Jan; Ron, C.; Chapanov, Ya. (2017). New determination of period and quality factor of Chandler wobble, considering geophysical excitations, Advances in Space Research, 5 (59), 1395-1407, 10.1016/j.asr.2016.12.001.
Title: New determination of period and quality factor of Chandler wobble, considering geophysical excitations
Type: Journal Article
Publication: Advances in Space Research
Author(s): Vondrák, Jan; Ron, C.; Chapanov, Ya.
Year: 2017
Formatted Citation: Vondrák, J., C. Ron, and Y. Chapanov, 2017: New determination of period and quality factor of Chandler wobble, considering geophysical excitations. Advances in Space Research, 59(5), 1395-1407, doi:10.1016/j.asr.2016.12.001
Ellsworth, David A.; Henze, Christopher E.; Nelson, Bron C. (2017). Interactive visualization of high-dimensional petascale ocean data, 2017 IEEE 7th Symposium on Large Data Analysis and Visualization (LDAV), 36-44, 10.1109/LDAV.2017.8231849.
Title: Interactive visualization of high-dimensional petascale ocean data
Type: Conference Proceedings
Publication: 2017 IEEE 7th Symposium on Large Data Analysis and Visualization (LDAV)
Author(s): Ellsworth, David A.; Henze, Christopher E.; Nelson, Bron C.
Year: 2017
Formatted Citation: Ellsworth, D. A., C. E. Henze, and B. C. Nelson, 2017: Interactive visualization of high-dimensional petascale ocean data. 2017 IEEE 7th Symposium on Large Data Analysis and Visualization (LDAV) IEEE, 36-44 pp. doi:10.1109/LDAV.2017.8231849.
Abstract: We describe an application for interactive visualization of 5 petabytes of time-varying multivariate data from a high-resolution global ocean circulation model. The input data are 10311 hourly (ocean time) time steps of various 2D and 3D fields from a 22-billion point 1/48-degree "lat-lon cap" configuration of the MIT General Circulation Model (MITgcm). We map the global horizontal model domain onto our 128-screen (8×16) tiled display wall to produce a canonical tiling with approximately one MITgcm grid point per display pixel, and using this tiling we encode the entire time series for multiple native and computed scalar quantities at a collection of ocean depths. We reduce disk bandwidth requirements by converting the model's floating point data to 16-bit fixed point values, and compressing those values with a lossless video encoder, which together allow synchronized playback at 24 time steps per second across all 128 displays. The application allows dynamic assignment of any two encoded tiles to any display, and has multiple interfaces for quickly specifying various orderly arrangements of tiles. All subsequent rendering is done on the fly, with run time control of colormaps, transfer functions, histogram equalization, and labeling. The two data streams on each screen can be rendered independently and combined in various ways, including blending, differencing, horizontal/vertical wipes, and checkerboarding. The two data streams on any screen can optionally be displayed as a scatterplot in their joint attribute space. All scatterplots and map-view plots from the same x/y location and depth are linked so they all show the current brushable selection. Ocean scientists have used the system, and have found previously unidentified features in the data.
Formatted Citation: Marshall, J., J. Scott, and A. Proshutinsky, 2017: "Climate response functions" for the Arctic Ocean: a proposed coordinated modelling experiment. Geoscientific Model Development, 10(7), 2833-2848, doi:10.5194/gmd-10-2833-2017
Abstract: A coordinated set of Arctic modelling experiments, which explore how the Arctic responds to changes in external forcing, is proposed. Our goal is to compute and compare climate response functions (CRFs) - the transient response of key observable indicators such as sea-ice extent, freshwater content of the Beaufort Gyre, etc. - to abrupt step changes in forcing fields across a number of Arctic models. Changes in wind, freshwater sources, and inflows to the Arctic basin are considered. Convolutions of known or postulated time series of these forcing fields with their respective CRFs then yield the (linear) response of these observables. This allows the project to inform, and interface directly with, Arctic observations and observers and the climate change community. Here we outline the rationale behind such experiments and illustrate our approach in the context of a coarse-resolution model of the Arctic based on the MITgcm. We conclude by summarizing the expected benefits of such an activity and encourage other modelling groups to compute CRFs with their own models so that we might begin to document their robustness to model formulation, resolution, and parameterization.
Title: Modeling Gas Budgets in Marginal Sea Ice Zones
Type: Thesis
Publication:
Author(s): Bigdeli, Arash
Year: 2017
Formatted Citation: Bigdeli, A., 2017: Modeling Gas Budgets in Marginal Sea Ice Zones., 114 pp. https://digitalcommons.uri.edu/oa_diss/678https://digitalcommons.uri.edu/oa_diss/678.
Abstract: Biogeochemical gas budgets at high-latitude regions and sea ice zones are a source of uncertainty in climate models. The four main processes that regulate these budgets include advection, ventilation, mixing, and accumulation/release from sea ice. Considering the scarcity of data in sea ice zones, specifically during winter time, the environment is too poorly sampled to constrain these processes through direct measurements; hence we proposed models to systematically investigate these processes. The models proposed in this dissertation consist of regional numerical ice-ocean models, 1D forward and inversion numerical models, and analytical models.
Dushaw, Brian D. (2017). Acoustic tomography as a component the Atlantic Ocean Observing System: Opportunities and Challenges, 8th EuroGOOS Conference, October, 5.
Title: Acoustic tomography as a component the Atlantic Ocean Observing System: Opportunities and Challenges
Type: Conference Proceedings
Publication: 8th EuroGOOS Conference
Author(s): Dushaw, Brian D.
Year: 2017
Formatted Citation: Dushaw, B. D., 2017: Acoustic tomography as a component the Atlantic Ocean Observing System: Opportunities and Challenges. 8th EuroGOOS Conference Nansen Environmental and Remote Sensing Center, Bergen, Norway(October), 5 pp. http://staff.washington.edu/dushaw/epubs/Dushaw_Tomography_8thEuroGOOSConference_2017.pdf.
Abstract: Ocean acoustic tomography is a unique measurement of large-scale ocean variability. The travel times of acoustic signals measure large-scale temperature, barotropic current, and, with an array of transceivers, relative vorticity. Applications include measurements of currents in shallow harbors, basin- and global-scale temperature, and deep-water formation events at high latitudes. Acoustical observations in ice-covered regions are compelling. All such systems provide for underwater GPS. The common perception that the Argo float system obviates the need for acoustic tomography is an error. While tomographic systems as components of regional or global-scale Ocean Observing Systems represent real opportunities for new insights into long-term ocean variability, the practical implementations of sustained acoustical systems are challenging. Such challenges are programmatic or cultural, rather than scientific, however. Given the extraordinary climatological changes presently occurring, it is imperative that all available observational capabilities be thoroughly considered. Studies employing numerical ocean models are required to design optimal observing strategies that exploit the complementary nature of different measurements. Observing Systems require practical techniques to implement data assimilation with the tomographic measurements. Programmatic technical capability and manpower to sustain acoustical measurements is lacking. Successful implementation of tomographic systems will require a stronger symbiotic relation between acousticians and oceanographers.
Su, Zhan (2017). Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale, Geophysical Research Letters, 12 (44), 6307-6315, 10.1002/2017GL073236.
Title: Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Su, Zhan
Year: 2017
Formatted Citation: Su, Z., 2017: Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale. Geophys. Res. Lett., 44(12), 6307-6315, doi:10.1002/2017GL073236
Title: Improved estimates and understanding of interannual trends of CO₂ fluxes in the Southern Ocean
Type: Thesis
Publication:
Author(s): Gregor, Luke
Year: 2017
Formatted Citation: Gregor, L., 2017: Improved estimates and understanding of interannual trends of CO₂ fluxes in the Southern Ocean., 176 pp.
Abstract: The Southern Ocean plays an important role in mitigating the effects of anthropogenically driven climate change. The region accounts for 43% of oceanic uptake of anthropogenic carbon dioxide (CO₂). This is foreseen to change with increasing greenhouse gas emissions due to ocean chemistry and climate feedbacks that regulate the carbon cycle in the Southern Ocean. Studies have already shown that Southern Ocean CO₂ is subject to interannual variability. Measuring and understanding this change has been difficult due to sparse observational data that is biased toward summer. This leaves a crucial gap in our understanding of the Southern Ocean CO₂ seasonal cycle, which needs to be resolved to adequately monitor change and gain insight into the drivers of interannual variability. Machine learning has been successful in estimating CO₂ in may parts of the ocean by extrapolating existing data with satellite measurements of proxy variables of CO₂. However, in the Southern Ocean machine learning has proven less successful. Large differences between machine learning estimates stem from the paucity of data and complexity of the mechanisms that drive CO₂. In this study the aim is to reduce the uncertainty of estimates, advance our understanding of the interannual drivers, and optimise sampling of CO₂ in the Southern Ocean. Improving the estimates of CO₂ was achieved by investigating: the impact of increasing the gridding resolution of input data and proxy variables, and Support vector regression (SVR) and Random Forest Regression (RFR) as alternate machine learning methods. It was found that the improvement gained by increasing gridding resolution was minimal and only RFR was able to improve on existing error estimates. Yet, there was good agreement of the seasonal cycle and interannual trends between RFR, SVR and estimates from the literature. The ensemble mean of these methods was used to investigate the variability and interannual trends of CO₂ in the Southern Ocean. The interannual trends of the ensemble confirmed trends reported in the literature. A weakening of the sink in the early 2000's, followed by a strengthening a strengthening of the sink into the early 2010's. Wind was the overall driver of dominant decadal interannual trends, being more important during winter due to the increased efficacy of entrainment processes. Summer interannual variability of CO₂ was driven primarily by chlorophyll, which responded to basin scale changes in drivers by the complex interaction with underlying physics and possibly sub-mesoscale processes. Lastly CO₂ sampling platforms, namely ships, profiling floats and moorings, were tested in an idealised simulated model environment using a machine learning approach. Ships, simulated from existing cruise tracks, failed to adequately resolve CO₂ below the uncertainty threshold that is required to resolve the seasonal cycle of Southern Ocean CO₂. Eight high frequency sampling moorings narrowly outperformed 200 profiling floats, which were both able to adequately resolve the seasonal cycle. Though, a combination of ships and profiling floats achieved the smallest error.
Other URLs: http://open.uct.ac.za/handle/11427/25320, http://hdl.handle.net/11427/25320
Zhang, Ying; Du, Yan; Zhang, Yuhong; Gao, Shan (2016). Asymmetry of upper ocean salinity response to the Indian Ocean dipole events as seen from ECCO simulation, Acta Oceanologica Sinica, 7 (35), 42-49, 10.1007/s13131-016-0904-z.
Title: Asymmetry of upper ocean salinity response to the Indian Ocean dipole events as seen from ECCO simulation
Type: Journal Article
Publication: Acta Oceanologica Sinica
Author(s): Zhang, Ying; Du, Yan; Zhang, Yuhong; Gao, Shan
Year: 2016
Formatted Citation: Zhang, Y., Y. Du, Y. Zhang, and S. Gao, 2016: Asymmetry of upper ocean salinity response to the Indian Ocean dipole events as seen from ECCO simulation. Acta Oceanologica Sinica, 35(7), 42-49, doi:10.1007/s13131-016-0904-z
Abstract: The interannual variability of salinity and associated ocean dynamics in the equatorial Indian Ocean is analyzed using observations and numerical simulations by the Estimating the Circulation and Climate of the Ocean (ECCO) model. The results show that salinity anomalies in the upper ocean are asymmetrically associated with the Indian Ocean dipole (IOD) events, with stronger response during their positive phases. Further investigations reveal that zonal currents along the equator, the Wyrtki jets, dominate the salinity transport. During the positive IOD events, the Wyrtki jets have stronger westward anomalies. The positive skewness of the IOD explains that the amplitude of the anomalous Wyrtki jets is stronger in the positive IOD events than that in the negative events.
Bender, Peter L; Betts, Casey R (2016). Ocean calibration approach for data from the GRACE Follow-On mission, Journal of Geophysical Research: Solid Earth, 2 (121), 1218-1235, 10.1002/2015JB012433.
Title: Ocean calibration approach for data from the GRACE Follow-On mission
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Bender, Peter L; Betts, Casey R
Year: 2016
Formatted Citation: Bender, P. L., and C. R. Betts, 2016: Ocean calibration approach for data from the GRACE Follow-On mission. Journal of Geophysical Research: Solid Earth, 121(2), 1218-1235, doi:10.1002/2015JB012433
Abstract: The Gravity Recovery and Climate Experiment (GRACE) mission has been providing valuable new information on time variations in the Earth's gravity field since 2002. In addition, the GRACE Follow?On mission is scheduled to be flown soon after the end of life of the GRACE mission in order to minimize the loss of valuable data on the Earth's gravity field changes. In view of the major benefits to hydrology and oceanography, as well as to other fields, it is desirable to investigate the fundamental limits to monitoring the time variations in the Earth's gravity field during GRACE?type missions. A simplified model is presented in this paper for making estimates of the effect of differential spurious accelerations of the satellites during times when four successive revolutions cross the Pacific Ocean. The analysis approach discussed is to make use of changes in the satellite separation observed during passages across low?latitude regions of the Pacific and of other oceans to correct for spurious accelerations of the satellites. The low?latitude regions of the Pacific and of other oceans are the extended regions where the a priori uncertainties in the time variations of the geopotential heights due to mass distribution changes are known best. In addition, advantage can be taken of the repeated crossings of the South Pole and the North Pole, since the uncertainties in changes in the geopotential heights at the poles during the time required for four orbit revolutions are likely to be small.
Keywords: ECCO-JPL ocean model, GRACE Follow-On mission, geopotential variations at satellite altitude, mass distribution variations
Schodlok, M P; Menemenlis, Dimitris; Rignot, E J (2016). Ice shelf basal melt rates around Antarctica from simulations and observations, Journal of Geophysical Research: Oceans, 2 (121), 1085-1109, 10.1002/2015JC011117.
Title: Ice shelf basal melt rates around Antarctica from simulations and observations
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Schodlok, M P; Menemenlis, Dimitris; Rignot, E J
Year: 2016
Formatted Citation: Schodlok, M. P., D. Menemenlis, and E. J. Rignot, 2016: Ice shelf basal melt rates around Antarctica from simulations and observations. J. Geophys. Res. Ocean., 121(2), 1085-1109, doi:10.1002/2015JC011117
Abstract: We introduce an explicit representation of Antarctic ice shelf cavities in the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) ocean retrospective analysis; and compare resulting basal melt rates and patterns to independent estimates from satellite observations. Two simulations are carried out: the first is based on the original ECCO2 vertical discretization; the second has higher vertical resolution particularly at the depth range of ice shelf cavities. The original ECCO2 vertical discretization produces higher than observed melt rates and leads to a misrepresentation of Southern Ocean water mass properties and transports. In general, thicker levels at the base of the ice shelves lead to increased melting because of their larger heat capacity. This strengthens horizontal gradients and circulation within and outside the cavities and, in turn, warm water transports from the shelf break to the ice shelves. The simulation with more vertical levels produces basal melt rates (1735 ± 164 Gt/a) and patterns that are in better agreement with observations. Thinner levels in the sub-ice-shelf cavities improve the representation of a fresh/cold layer at the ice shelf base and of warm/salty water near the bottom, leading to a sharper pycnocline and reduced vertical mixing underneath the ice shelf. Improved water column properties lead to more accurate melt rates and patterns, especially for melt/freeze patterns under large cold-water ice shelves. At the 18 km grid spacing of the ECCO2 model configuration, the smaller, warm-water ice shelves cannot be properly represented, with higher than observed melt rates in both simulations.
Ashkezari, Mohammad D; Hill, Christopher N; Follett, Christopher N; Forget, Gaël; Follows, Michael J. (2016). Oceanic eddy detection and lifetime forecast using machine learning methods, Geophysical Research Letters, 23 (43), 12,212-234,241, 10.1002/2016GL071269.
Title: Oceanic eddy detection and lifetime forecast using machine learning methods
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Ashkezari, Mohammad D; Hill, Christopher N; Follett, Christopher N; Forget, Gaël; Follows, Michael J.
Year: 2016
Formatted Citation: Ashkezari, M. D., C. N. Hill, C. N. Follett, G. Forget, and M. J. Follows, 2016: Oceanic eddy detection and lifetime forecast using machine learning methods. Geophys. Res. Lett., 43(23), 12,212-234,241, doi:10.1002/2016GL071269
Abstract: We report a novel altimetry-based machine learning approach for eddy identification and characterization. The machine learning models use daily maps of geostrophic velocity anomalies and are trained according to the phase angle between the zonal and meridional components at each grid point. The trained models are then used to identify the corresponding eddy phase patterns and to predict the lifetime of a detected eddy structure. The performance of the proposed method is examined at two dynamically different regions to demonstrate its robust behavior and region independency.
Pillar, Helen R; Heimbach, Patrick; Johnson, Helen L; Marshall, David P (2016). Dynamical attribution of recent variability in Atlantic overturning, Journal of Climate, 9 (29), 3339-3352, 10.1175/JCLI-D-15-0727.1.
Title: Dynamical attribution of recent variability in Atlantic overturning
Type: Journal Article
Publication: Journal of Climate
Author(s): Pillar, Helen R; Heimbach, Patrick; Johnson, Helen L; Marshall, David P
Year: 2016
Formatted Citation: Pillar, H. R., P. Heimbach, H. L. Johnson, and D. P. Marshall, 2016: Dynamical attribution of recent variability in Atlantic overturning. J. Clim., 29(9), 3339-3352, doi:10.1175/JCLI-D-15-0727.1
Jones, Daniel C; Meijers, Andrew J S; Shuckburgh, Emily; Sallée, Jean-Baptiste; Haynes, Peter; McAufield, Ewa K; Mazloff, Matthew R (2016). How does Subantarctic Mode Water ventilate the Southern Hemisphere subtropics?, Journal of Geophysical Research: Oceans, 9 (121), 6558-6582, 10.1002/2016JC011680.
Title: How does Subantarctic Mode Water ventilate the Southern Hemisphere subtropics?
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Jones, Daniel C; Meijers, Andrew J S; Shuckburgh, Emily; Sallée, Jean-Baptiste; Haynes, Peter; McAufield, Ewa K; Mazloff, Matthew R
Year: 2016
Formatted Citation: Jones, D. C., A. J. S. Meijers, E. Shuckburgh, J. Sallée, P. Haynes, E. K. McAufield, and M. R. Mazloff, 2016: How does Subantarctic Mode Water ventilate the Southern Hemisphere subtropics? J. Geophys. Res. Ocean., 121(9), 6558-6582, doi:10.1002/2016JC011680
Abstract: In several regions north of the Antarctic Circumpolar Current (ACC), deep wintertime convection refreshes pools of weakly stratified subsurface water collectively referred to as Subantarctic Mode Water (SAMW). SAMW ventilates the subtropical thermocline on decadal timescales, providing nutrients for low-latitude productivity and potentially trapping anthropogenic carbon in the deep ocean interior for centuries. In this work, we investigate the spatial structure and timescales of mode water export and associated thermocline ventilation. We use passive tracers in an eddy-permitting, observationally-informed Southern Ocean model to identify the pathways followed by mode waters between their formation regions and the areas where they first enter the subtropics. We find that the pathways followed by the mode water tracers are largely set by the mean geostrophic circulation. Export from the Indian and Central Pacific mode water pools is primarily driven by large-scale gyre circulation, whereas export from the Australian and Atlantic pools is heavily influenced by the ACC. Export from the Eastern Pacific mode water pool is driven by a combination of deep boundary currents and subtropical gyre circulation. More than 50% of each mode water tracer reaches the subtropical thermocline within 50 years, with significant variability between pools. The Eastern Pacific pathway is especially efficient, with roughly 80% entering the subtropical thermocline within 50 years. The time required for 50% of the mode water tracers to leave the Southern Ocean domain varies significantly between mode water pools, from 9 years for the Indian mode water pool to roughly 40 years for the Central Pacific mode water pool.
Keywords: 0545 Modeling, 4223 Descriptive and regional oceanography, 4283 Water masses, 4513 Decadal ocean variability, 4532 General circulation, Southern Ocean, Subantarctic Mode Water, circulation, modeling, thermocline, ventilation
Formatted Citation: Tagliabue, A. and Coauthors, 2016: How well do global ocean biogeochemistry models simulate dissolved iron distributions? Global Biogeochemical Cycles, 30(2), 149-174, doi:10.1002/2015gb005289
Abstract: Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.
Rocha, Cesar B; Gille, Sarah T; Chereskin, Teresa K; Menemenlis, Dimitris (2016). Seasonality of submesoscale dynamics in the Kuroshio Extension, Geophys. Res. Lett., 21 (43), 11304-11311, 10.1002/2016GL071349.
Title: Seasonality of submesoscale dynamics in the Kuroshio Extension
Type: Journal Article
Publication: Geophys. Res. Lett.
Author(s): Rocha, Cesar B; Gille, Sarah T; Chereskin, Teresa K; Menemenlis, Dimitris
Year: 2016
Formatted Citation: Rocha, C. B., S. T. Gille, T. K. Chereskin, and D. Menemenlis, 2016: Seasonality of submesoscale dynamics in the Kuroshio Extension. Geophys. Res. Lett., 43(21), 11304-11311, doi:10.1002/2016GL071349
Abstract: Recent studies show that the vigorous seasonal cycle of the mixed layer modulates upper ocean submesoscale turbulence. Here we provide model-based evidence that the seasonally changing upper ocean stratification in the Kuroshio Extension also modulates submesoscale (here 10-100 km) inertia-gravity waves. Summertime restratification weakens submesoscale turbulence but enhances inertia-gravity waves near the surface. Thus, submesoscale turbulence and inertia-gravity waves undergo vigorous out-of-phase seasonal cycles. These results imply a strong seasonal modulation of the accuracy of geostrophic velocity diagnosed from submesoscale sea surface height delivered by the SurfaceWater and Ocean Topography satellite mission.
Liang, Xinfeng; Yu, Lisan (2016). Variations of the Global Net Air-Sea Heat Flux during the "Hiatus" Period (2001-10), Journal of Climate, 10 (29), 3647-3660, 10.1175/JCLI-D-15-0626.1.
Title: Variations of the Global Net Air-Sea Heat Flux during the "Hiatus" Period (2001-10)
Type: Journal Article
Publication: Journal of Climate
Author(s): Liang, Xinfeng; Yu, Lisan
Year: 2016
Formatted Citation: Liang, X., and L. Yu, 2016: Variations of the Global Net Air-Sea Heat Flux during the "Hiatus" Period (2001-10). J. Clim., 29(10), 3647-3660, doi:10.1175/JCLI-D-15-0626.1
Abstract: An assessment is made of the mean and variability of the net air-sea heat flux, Qnet, from four products (ECCO, OAFlux-CERES, ERA-Interim, and NCEP1) over the global ice-free ocean from January 2001 to December 2010. For the 10-yr "hiatus" period, all products agree on an overall net heat gain over the global ice-free ocean, but the magnitude varies from 1.7 to 9.5 W m−2. The differences among products are particularly large in the Southern Ocean, where they cannot even agree on whether the region gains or loses heat on the annual mean basis. Decadal trends of Qnet differ significantly between products. ECCO and OAFlux-CERES show almost no trend, whereas ERA-Interim suggests a downward trend and NCEP1 shows an upward trend. Therefore, numerical simulations utilizing different surface flux forcing products will likely produce diverged trends of the ocean heat content during this period. The downward trend in ERA-Interim started from 2006, driven by a peculiar pattern change in the tropical regions....
Ponte, R M; Vinogradova, N T (2016). An assessment of basic processes controlling mean surface salinity over the global ocean, Geophysical Research Letters, 13 (43), 7052-7058, 10.1002/2016GL069857.
Title: An assessment of basic processes controlling mean surface salinity over the global ocean
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Ponte, R M; Vinogradova, N T
Year: 2016
Formatted Citation: Ponte, R. M., and N. T. Vinogradova, 2016: An assessment of basic processes controlling mean surface salinity over the global ocean. Geophys. Res. Lett., 43(13), 7052-7058, doi:10.1002/2016GL069857
Abstract: A data-constrained ocean state estimate that permits closed property budget diagnostics is used to examine the balance between surface forcing ( F¯), advective ( A¯), and diffusive ( D¯) fluxes in maintaining the large-scale time-mean surface salinity Ss¯. Time-mean budgets (1993-2010) are considered for the 10 m thick top layer. In general, D¯ tends to counteract F¯, but A¯ is important almost everywhere, and some regions show a main balance between A¯ and D¯ (Bay of Bengal, Arctic) or A¯ and F¯ (tropical Atlantic and Pacific). Advection tends to freshen the surface in the tropics and high latitudes, with opposite tendencies in midlatitudes. For various Ss¯ tropical extrema, A¯ adds to the F¯ tendencies in precipitation regions and opposes F¯ in evaporation regions. Long-term Ss¯ conditions thus reflect more than a simple diffusive adjustment to F¯, likely involving close interaction between wind- and buoyancy-driven circulation and mixing processes.
Keywords: 4215 Climate and interannual variability, 4260 Ocean data assimilation and reanalysis, 4504 Air/sea interactions, 4532 General circulation, 4572 Upper ocean and mixed layer processes, freshwater flux, surface salinity
Vondrák, Jan; Ron, Cyril (2016). Geophysical fluids from different data sources, geomagnetic jerks, and their impact on Earth´s orientation, Acta Geodynamica et Geomaterialia, 3 (13), 241-247, 10.13168/AGG.2016.0005.
Title: Geophysical fluids from different data sources, geomagnetic jerks, and their impact on Earth´s orientation
Type: Journal Article
Publication: Acta Geodynamica et Geomaterialia
Author(s): Vondrák, Jan; Ron, Cyril
Year: 2016
Formatted Citation: Vondrák, J., and C. Ron, 2016: Geophysical fluids from different data sources, geomagnetic jerks, and their impact on Earth´s orientation. Acta Geodynamica et Geomaterialia, 13(3), 241-247, doi:10.13168/AGG.2016.0005
Abstract: Recently we studied the effects of geophysical fluids (atmosphere, oceans) and geomagnetic jerks in Earth's orientation in space (Vondrak and Ron, 2010; Ron and Vondrak, 2011). To this end, we used the American NCEP/NCAR model of the atmosphere and ECCO model of the oceans (Vondrak and Ron, 2015). Here we concentrate on other available models of geophysical fluids, such as ERA and MERRA for the atmosphere, and OMCT for the oceans, and compare the results obtained with all of them. We also test the hypothetic effect of geomagnetic jerks together with these alternative models and study how much the agreement with the observed Earth Orientation Parameters is improved. By using numerical integration of all five Earth orientation parameters, we demonstrate that different models of atmospheric/oceanic excitations lead to slightly different results, fitting relatively well with their observed values but showing changes both in amplitude and phase. In all cases the agreement improves substantially when the effect of geomagnetic jerks is added to geophysical fluids, and the differences in amplitude/phase almost disappear.
Keywords:
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Chien, Chia-Te; Mackey, Katherine R M; Dutkiewicz, Stephanie; Mahowald, Natalie M; Prospero, Joseph M; Paytan, Adina (2016). Effects of African dust deposition on phytoplankton in the western tropical Atlantic Ocean off Barbados, Global Biogeochemical Cycles, 5 (30), 716-734, 10.1002/2015GB005334.
Title: Effects of African dust deposition on phytoplankton in the western tropical Atlantic Ocean off Barbados
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): Chien, Chia-Te; Mackey, Katherine R M; Dutkiewicz, Stephanie; Mahowald, Natalie M; Prospero, Joseph M; Paytan, Adina
Year: 2016
Formatted Citation: Chien, C., K. R. M. Mackey, S. Dutkiewicz, N. M. Mahowald, J. M. Prospero, and A. Paytan, 2016: Effects of African dust deposition on phytoplankton in the western tropical Atlantic Ocean off Barbados. Global Biogeochemical Cycles, 30(5), 716-734, doi:10.1002/2015GB005334
Abstract: Bioassay incubation experiments conducted with nutrients and local atmospheric aerosol amendments indicate that phosphorus (P) availability limited phytoplankton growth in the low-nutrient low-chlorophyll (LNLC) ocean off Barbados. Atmospheric deposition provides a relatively large influx of new nutrients and trace metals to the surface ocean in this region in comparison to other nutrient sources. However, the impact on native phytoplankton is muted due to the high ratio of nitrogen (N) to P (NO3:SRP > 40) and the low P solubility of these aerosols. Atmospheric deposition induces P limitation in this LNLC region by adding more N and iron (Fe) relative to P. This favors the growth of Prochlorococcus, a genus characterized by low P requirements and highly efficient P acquisition mechanisms. A global three-dimensional marine ecosystem model that includes species-specific phytoplankton elemental quotas/stoichiometry and the atmospheric deposition of N, P, and Fe supports this conclusion. Future increases in aerosol N loading may therefore influence phytoplankton community structure in other LNLC areas, thereby affecting the biological pump and associated carbon sequestration.
Keywords: 0414 Biogeochemical cycles, 0470 Nutrients and nutrient cycling, 4801 Aerosols, 4858 Population dynamics and ecology, Barbados, and modeling, atmospheric deposition, nutrient limitation, phytoplankton community structure, processes
Other URLs: http://doi.wiley.com/10.1002/2015GB005334
Stammer, D; Balmaseda, M; Heimbach, P; Kohl, A; Weaver, A (2016). Ocean Data Assimilation in Support of Climate Applications: Status and Perspectives, Ann Rev Mar Sci (8), 491-518, 10.1146/annurev-marine-122414-034113.
Title: Ocean Data Assimilation in Support of Climate Applications: Status and Perspectives
Type: Journal Article
Publication: Ann Rev Mar Sci
Author(s): Stammer, D; Balmaseda, M; Heimbach, P; Kohl, A; Weaver, A
Year: 2016
Formatted Citation: Stammer, D., M. Balmaseda, P. Heimbach, A. Kohl, and A. Weaver, 2016: Ocean Data Assimilation in Support of Climate Applications: Status and Perspectives. Ann Rev Mar Sci, 8, 491-518, doi:10.1146/annurev-marine-122414-034113
Abstract: Ocean data assimilation brings together observations with known dynamics encapsulated in a circulation model to describe the time-varying ocean circulation. Its applications are manifold, ranging from marine and ecosystem forecasting to climate prediction and studies of the carbon cycle. Here, we address only climate applications, which range from improving our understanding of ocean circulation to estimating initial or boundary conditions and model parameters for ocean and climate forecasts. Because of differences in underlying methodologies, data assimilation products must be used judiciously and selected according to the specific purpose, as not all related inferences would be equally reliable. Further advances are expected from improved models and methods for estimating and representing error information in data assimilation systems. Ultimately, data assimilation into coupled climate system components is needed to support ocean and climate services. However, maintaining the infrastructure and expertise for sustained data assimilation remains challenging.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4;GECCO2
URL:
Other URLs:
Rignot, E; Xu, Y; Menemenlis, Dimitris; Mouginot, J; Scheuchl, B; Li, X; Morlighem, M; Seroussi, Hélène; van den Broeke, M; Fenty, Ian; Cai, C; An, L; de Fleurian, B (2016). Modeling of ocean-induced ice melt rates of five west Greenland glaciers over the past two decades, Geophysical Research Letters, 12 (43), 6374-6382, 10.1002/2016GL068784.
Title: Modeling of ocean-induced ice melt rates of five west Greenland glaciers over the past two decades
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Rignot, E; Xu, Y; Menemenlis, Dimitris; Mouginot, J; Scheuchl, B; Li, X; Morlighem, M; Seroussi, Hélène; van den Broeke, M; Fenty, Ian; Cai, C; An, L; de Fleurian, B
Year: 2016
Formatted Citation: Rignot, E. and Coauthors, 2016: Modeling of ocean-induced ice melt rates of five west Greenland glaciers over the past two decades. Geophys. Res. Lett., 43(12), 6374-6382, doi:10.1002/2016GL068784
Abstract: High-resolution, three-dimensional simulations from the Massachusetts Institute of Technology general circulation model ocean model are used to calculate the subaqueous melt rate of the calving faces of Umiamako, Rinks, Kangerdlugssup, Store, and Kangilerngata glaciers, west Greenland, from 1992 to 2015. Model forcing is from monthly reconstructions of ocean state and ice sheet runoff. Results are analyzed in combination with observations of bathymetry, bed elevation, ice front retreat, and glacier speed. We calculate that subaqueous melt rates are 2?3 times larger in summer compared to winter and doubled in magnitude since the 1990s due to enhanced subglacial runoff and 1.6 ± 0.3°C warmer ocean temperature. Umiamako and Kangilerngata retreated rapidly in the 2000s when subaqueous melt rates exceeded the calving rates and ice front retreated to deeper bed elevation. In contrast, Store, Kangerdlugssup, and Rinks have remained stable because their subaqueous melt rates are 3?4 times lower than their calving rates, i.e., the glaciers are dominated by calving processes.
Keywords: calving, glaciology, greenland, ice-ocean interaction, mass balance, subaqueous melt
Title: Stochastic secular trends in sea level rise
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Ocaña, Victor; Zorita, Eduardo; Heimbach, Patrick
Year: 2016
Formatted Citation: Ocaña, V., E. Zorita, and P. Heimbach, 2016: Stochastic secular trends in sea level rise. J. Geophys. Res. Ocean., 121(4), 2183-2202, doi:10.1002/2015JC011301
Abstract: Global mean sea level (GMSL) has been rising since (at least) the nineteenth century and the rate of rise may be increasing. Several studies that attempt to explain the long-term trend of GMSL during the instrumental record share the common assumption that this trend is deterministic in nature and different from natural variations. Here we show that the trend can alternatively be explained, at least in part, as being caused by random variations within the coupled ocean-atmosphere-cryosphere system, and hence not having a deterministic origin. These random trends, which add to externally forced changes (e.g., through anthropogenic climate change), are a consequence of the integrated character of GMSL, which is the cumulative addition of temporal contributions that exhibit random character, and whose integration results in GMSL variations with persistence on decadal-centennial time scales. The generation of trends by integration of random stationary noise (i.e., even in a constant climate) is a robust and fundamental feature of stochastically forced systems with memory. The integrated character of GMSL results in an intrinsic difficulty in distinguishing internal from externally forced trends.
Keywords: 1641 Sea level change, 4215 Climate and interannual variability, 4540 Ice mechanics and air/sea/ice exchange proces, 4556 Sea level: variations and mean, autoregressive/integrated process, ocean variability, sea level
Chaudhuri, A H; Ponte, R M; Forget, G (2016). Impact of uncertainties in atmospheric boundary conditions on ocean model solutions, Ocean Modelling (100), 96-108, 10.1016/j.ocemod.2016.02.003.
Title: Impact of uncertainties in atmospheric boundary conditions on ocean model solutions
Type: Journal Article
Publication: Ocean Modelling
Author(s): Chaudhuri, A H; Ponte, R M; Forget, G
Year: 2016
Formatted Citation: Chaudhuri, A. H., R. M. Ponte, and G. Forget, 2016: Impact of uncertainties in atmospheric boundary conditions on ocean model solutions. Ocean Modelling, 100, 96-108, doi:10.1016/j.ocemod.2016.02.003
Abstract: We quantify differences in ocean model simulations derived solely from atmospheric uncertainties and investigate how they relate to overall model errors as inferred from comparisons with data. For this purpose, we use a global configuration of the MITgcm to simulate 4 ocean solutions for 2000-2009 using 4 reanalysis products (JRA-25, MERRA, CFSR and ERA-Interim) as atmospheric forcing. The simulations are compared against observations and against each other for selected variables (temperature, sea-level, sea-ice, streamfunctions, meridional heat and freshwater transports). Forcing-induced differences are comparable in magnitude to model-observation misfits for most near-surface variables in the tropics and sub-tropics, but typically smaller at higher latitudes and polar regions. Forcing-derived differences are expectedly largest near the surface and mostly limited to the upper 1000 m but can also be seen as deep as 4000 m, especially in regions of deep water formation. Errors are not necessarily local in nature and can be advected to different basins. Results indicate that while forcing adjustments might suffice in optimization procedures of near-surface fields and at low-to-mid latitudes, other control parameters are likely needed elsewhere. Forcing-induced differences can be dominated by large spatial scales and specific time scales (e.g. annual), and thus appropriate error covariances in space and time need to be considered in optimization methodologies. (C) 2016 Elsevier Ltd. All rights reserved.
Nicholson, D P; Khatiwala, S; Heimbach, P (2016). Noble gas tracers of ventilation during deep-water formation in the Weddell Sea.
Title: Noble gas tracers of ventilation during deep-water formation in the Weddell Sea
Type: Journal Article
Publication:
Author(s): Nicholson, D P; Khatiwala, S; Heimbach, P
Year: 2016
Formatted Citation: Nicholson, D. P., S. Khatiwala, and P. Heimbach, 2016: Noble gas tracers of ventilation during deep-water formation in the Weddell Sea., 35(1), 12011-12019
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ECCO Products Used:
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Thompson, P R; Piecuch, C G; Merrifield, M A; McCreary, J P; Firing, E (2016). Forcing of recent decadal variability in the Equatorial and North Indian Ocean, Journal of Geophysical Research: Oceans, 9 (121), 6762-6778, 10.1002/2016JC012132.
Title: Forcing of recent decadal variability in the Equatorial and North Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Thompson, P R; Piecuch, C G; Merrifield, M A; McCreary, J P; Firing, E
Year: 2016
Formatted Citation: Thompson, P. R., C. G. Piecuch, M. A. Merrifield, J. P. McCreary, and E. Firing, 2016: Forcing of recent decadal variability in the Equatorial and North Indian Ocean. J. Geophys. Res. Ocean., 121(9), 6762-6778, doi:10.1002/2016JC012132
Abstract: Recent decadal sea surface height (SSH) variability across the Equatorial and North Indian Ocean (ENIO, north of 5°S) is spatially coherent and related to a reversal in basin-scale, upper-ocean-temperature trends. Analysis of ocean and forcing fields from a data-assimilating ocean synthesis (ECCOv4) suggests that two equally important mechanisms of wind-driven heat redistribution within the Indian Ocean account for a majority of the decadal variability. The first is the Cross-Equatorial Cell (CEC) forced by zonal wind stress curl at the equator. The wind stress curl variability relates to the strength and position of the Mascarene High, which is influenced by the phase of the Indian Ocean Subtropical Dipole. The second mechanism is deep (700 m) upwelling related to zonal wind stress at the equator that causes deep, cross-equatorial overturning due to the unique geometry of the basin. The CEC acts to cool the upper ocean throughout most of the first decade of satellite altimetry, while the deep upwelling delays and then amplifies the effect of the CEC on SSH. During the subsequent decade, reversals in the forcing anomalies drive warming of the upper ocean and increasing SSH, with the effect of the deep upwelling leading the CEC.
Keywords: 4215 Climate and interannual variability, 4513 Decadal ocean variability, 4556 Sea level: variations and mean, ECCOv4, Indian Ocean, decadal variability, satellite altimetry, sea surface height
Title: Contrasting Effects of Historical Sea Level Rise and Contemporary Ocean Currents on Regional Gene Flow of Rhizophora racemosa in Eastern Atlantic Mangroves
Type: Journal Article
Publication: PLoS ONE
Author(s): Ngeve, Magdalene N; Van der Stocken, Tom; Menemenlis, Dimitris; Koedam, Nico; Triest, Ludwig
Year: 2016
Formatted Citation: Ngeve, M. N., T. Van der Stocken, D. Menemenlis, N. Koedam, and L. Triest, 2016: Contrasting Effects of Historical Sea Level Rise and Contemporary Ocean Currents on Regional Gene Flow of Rhizophora racemosa in Eastern Atlantic Mangroves. PLoS ONE, 11(3), e0150950, doi:10.1371/journal.pone.0150950
Abstract: Mangroves are seafaring taxa through their hydrochorous propagules that have the potential to disperse over long distances. Therefore, investigating their patterns of gene flow provides insights on the processes involved in the spatial genetic structuring of populations. The coastline of Cameroon has a particular geomorphological history and coastal hydrology with complex contemporary patterns of ocean currents, which we hypothesize to have effects on the spatial configuration and composition of present-day mangroves within its spans. A total of 982 trees were sampled from 33 transects (11 sites) in 4 estuaries. Using 11 polymorphic SSR markers, we investigated genetic diversity and structure of Rhizophora racemosa, a widespread species in the region. Genetic diversity was low to moderate and genetic differentiation between nearly all population pairs was significant. Bayesian clustering analysis, PCoA, estimates of contemporary migration rates and identification of barriers to gene flow were used and complemented with estimated dispersal trajectories of hourly released virtual propagules, using high-resolution surface current from a mesoscale and tide-resolving ocean simulation. These indicate that the Cameroon Volcanic Line (CVL) is not a present-day barrier to gene flow. Rather, the Inter-Bioko-Cameroon (IBC) corridor, formed due to sea level rise, allows for connectivity between two mangrove areas that were isolated during glacial times by the CVL. Genetic data and numerical ocean simulations indicated that an oceanic convergence zone near the Cameroon Estuary complex (CEC) presents a strong barrier to gene flow, resulting in genetic discontinuities between the mangrove areas on either side. This convergence did not result in higher genetic diversity at the CEC as we had hypothesized. In conclusion, the genetic structure of Rhizophora racemosa is maintained by the contrasting effects of the contemporary oceanic convergence and historical climate change-induced sea level rise.
Song, Hajoon; Marshall, John; Follows, Michael J.; Dutkiewicz, Stephanie; Forget, Gaël (2016). Source waters for the highly productive Patagonian shelf in the southwestern Atlantic, Journal of Marine Systems (158), 120-128, 10.1016/j.jmarsys.2016.02.009.
Formatted Citation: Song, H., J. Marshall, M. J. Follows, S. Dutkiewicz, and G. Forget, 2016: Source waters for the highly productive Patagonian shelf in the southwestern Atlantic. Journal of Marine Systems, 158, 120-128, doi:10.1016/j.jmarsys.2016.02.009
Abstract: Possible nutrient sources and delivery mechanisms for the highly productive Patagonian shelf in the southwest Atlantic are identified. Using a passive tracer adjoint sensitivity experiment, we identify three source waters: waters local to the Patagonian shelf, coastal waters near the Chilean coast and the subsurface waters in the southeast Pacific. We perform a series of forward simulations of a biogeochemical model to investigate the impact of nutrient perturbations in these source regions to productivity on the Patagonian shelf. Positive nitrate perturbations from local waters have an immediate impact elevating productivity. Iron perturbations local to the shelf, however, do not change productivity because the shelf region is limited by nitrate. Additional nutrient supply from the other source regions leads to increases in productivity. We find that positive nutrient perturbations in subsurface waters in the southeast Pacific result in the largest boost of productivity over the shelf. These source waters are rich in nutrients and upwelled from the depth where light levels are so low that they cannot be consumed. Finally, we identify wintertime intense vertical mixing as the key process which draws nutrients from below 300-500 m to the surface before being delivered to the shelf.
Formatted Citation: Vinogradova, N., T. Lee, P. Durack, J. Boutin, and D. Stammer, 2016: Ocean Salinity and the Water Cycle: Recent Progress and Future Challenges. GEWEX News, 6-8 pp.
Abstract:
Keywords:
ECCO Products Used: ECCO-V4
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Rocha, Cesar B; Chereskin, Teresa K; Gille, Sarah T; Menemenlis, Dimitris (2016). Mesoscale to Submesoscale Wavenumber Spectra in Drake Passage, Journal of Physical Oceanography, 2 (46), 601-620, 10.1175/JPO-D-15-0087.1.
Title: Mesoscale to Submesoscale Wavenumber Spectra in Drake Passage
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Rocha, Cesar B; Chereskin, Teresa K; Gille, Sarah T; Menemenlis, Dimitris
Year: 2016
Formatted Citation: Rocha, C. B., T. K. Chereskin, S. T. Gille, and D. Menemenlis, 2016: Mesoscale to Submesoscale Wavenumber Spectra in Drake Passage. Journal of Physical Oceanography, 46(2), 601-620, doi:10.1175/JPO-D-15-0087.1
Abstract: This study discusses the upper-ocean (0-200 m) horizontal wavenumber spectra in the Drake Passage from 13 yr of shipboard ADCP measurements, altimeter data, and a high-resolution numerical simulation. At scales between 10 and 200 km, the ADCP kinetic energy spectra approximately follow a k−3 power law. The observed flows are more energetic at the surface, but the shape of the kinetic energy spectra is independent of depth. These characteristics resemble predictions of isotropic interior quasigeostrophic turbulence. The ratio of across-track to along-track kinetic energy spectra, however, significantly departs from the expectation of isotropic interior quasigeostrophic turbulence. The inconsistency is dramatic at scales smaller than 40 km. A Helmholtz decomposition of the ADCP spectra and analyses of synthetic and numerical model data show that horizontally divergent, ageostrophic flows account for the discrepancy between the observed spectra and predictions of isotropic interior quasigeostrophic turbulence. In Drake Passage, ageostrophic motions appear to be dominated by inertia-gravity waves and account for about half of the near-surface kinetic energy at scales between 10 and 40 km. Model results indicate that ageostrophic flows imprint on the sea surface, accounting for about half of the sea surface height variance between 10 and 40 km.
Title: Annual variation detected by GPS, GRACE and loading models
Type: Journal Article
Publication: Studia Geophysica et Geodaetica
Author(s): Li, Weiwei; van Dam, Tonie; Li, Zhao; Shen, Yunzhong
Year: 2016
Formatted Citation: Li, W., T. van Dam, Z. Li, and Y. Shen, 2016: Annual variation detected by GPS, GRACE and loading models. Studia Geophysica et Geodaetica, 60(4), 608-621, doi:10.1007/s11200-016-0205-1
Abstract: Most GPS coordinate time series, surface displacements derived from the Gravity Recovery and Climate Experiment (GRACE), and loading models display significant annual signals at many regions. This paper compares the annual signals of the GPS position time series from the Crustal Dynamics Data Information System (CDDIS), estimates of loading from GRACE monthly gravity field models calculated by three processing centers (Center of Spatial Research, CSR; Jet Propulsion Laboratory, JPL; GeoForschungsZentrum, GFZ) and three geophysical fluids models (National Center for Environmental Prediction, NCEP; Estimating the Circulation and Climate of the Ocean, ECCO; Global Land Data Assimilation System, GLDAS) for 270 globally distributed stations for the period 2003-2011. The results show that annual variations derived from the level-2 products from the three GRACE product centers are very similar. The absolute difference in annual amplitude between any two centers is never larger than 1.25 mm in the vertical and 0.11 mm in horizontal displacement. The mean phase differences of the GRACE results are less than ten days for all three components. When we correct the GPS vertical coordinate time series using the GRACE annual amplitudes using the products from three GRACE analysis centers, we find that we are able to reduce the GPS annual signal in the vertical at about 80% stations and the average reduction is about 47%. In the north and the east, the annual amplitude is reduced on 77% and 72% of the stations with the average reduction 32% and 33%. We also compare the annual surface displacement signal derived from two environmental models; the two models use the same atmospheric and non-tidal ocean loading and differ only in the continental water storage model that we use, either NCEP or GLDAS. We find that the model containing the GLDAS continental water storage is able to better reduce the annual signal in the GPS coordinate time series.
Title: North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability
Type: Journal Article
Publication: Ocean Modelling
Author(s): Danabasoglu, Gokhan; Yeager, Steve G; Kim, Who M; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Karspeck, Alicia R; Kelley, Maxwell; Large, William G; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J; Masina, Simona; Navarra, Antonio; Nurser, A J George; Pirani, Anna; Romanou, Anastasia; Salas y Mélia, David; Samuels, Bonita L; Scheinert, Markus; Sidorenko, Dmitry; Sun, Shan; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yashayaev, Igor
Year: 2016
Formatted Citation: Danabasoglu, G. and Coauthors, 2016: North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability. Ocean Modelling, 97, 65-90, doi:10.1016/j.ocemod.2015.11.007
Abstract: Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which include the influence of ocean dynamics from nature superimposed onto anthropogenic effects. Despite these general agreements, there are many differences among the model solutions, particularly in the spatial structures of variability patterns. For example, the location of the maximum AMOC variability differs among the models between Northern and Southern Hemispheres.
Keywords: Atlantic meridional overturning circulation variab, Atmospheric forcing, Global ocean - sea-ice modelling, Inter-annual to decadal variability and mechanisms, Ocean model comparisons, Variability in the North Atlantic
Piecuch, Christopher G; Dangendorf, Sönke; Ponte, Rui M; Marcos, Marta (2016). Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions, Journal of Climate, 13 (29), 4801-4816, 10.1175/JCLI-D-16-0048.1.
