Publications
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. You might be interested in our "Research Roundup" StoryMaps for 2023, 2022, 2021 and 2020.
Publications: 257
Title: Vertical bedrock shifts reveal summer water storage in Greenland ice sheet
Type: Journal Article
Publication: Nature
Author(s): Ran, Jiangjun; Ditmar, Pavel; van den Broeke, Michiel R.; Liu, Lin; Klees, Roland; Khan, Shfaqat Abbas; Moon, Twila; Li, Jiancheng; Bevis, Michael; Zhong, Min; Fettweis, Xavier; Liu, Junguo; Noël, Brice; Shum, C. K.; Chen, Jianli; Jiang, Liming; van Dam, Tonie
Year: 2024
Formatted Citation: Ran, J. and Coauthors, 2024: Vertical bedrock shifts reveal summer water storage in Greenland ice sheet. Nature, 635(8037), 108-113, doi:10.1038/s41586-024-08096-3
Abstract:
The Greenland ice sheet (GrIS) is at present the largest single contributor to global-mass-induced sea-level rise, primarily because of Arctic amplification on an increasingly warmer Earth. However, the processes of englacial water accumulation, storage and ultimate release remain poorly constrained. Here we show that a noticeable amount of the summertime meltwater mass is temporally buffered along the entire GrIS periphery, peaking in July and gradually reducing thereafter. Our results arise from quantifying the spatiotemporal behaviour of the total mass of water leaving the GrIS by analysing bedrock elastic deformation measured by Global Navigation Satellite System (GNSS) stations. The buffered meltwater causes a subsidence of the bedrock close to GNSS stations of at most approximately 5 mm during the melt season. Regionally, the duration of meltwater storage ranges from 4.5 weeks in the southeast to 9 weeks elsewhere. We also show that the meltwater runoff modelled from regional climate models may contain systematic errors, requiring further scaling of up to about 20% for the warmest years. These results reveal a high potential for GNSS data to constrain poorly known hydrological processes in Greenland, forming the basis for improved projections of future GrIS melt behaviour and the associated sea-level rise.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Rosat, S.; Gillet, N. (2023). Intradecadal variations in length of day: Coherence with models of the Earth’s core dynamics, Physics of the Earth and Planetary Interiors (341), 107053, 10.1016/j.pepi.2023.107053.
Title: Intradecadal variations in length of day: Coherence with models of the Earth’s core dynamics
Type: Journal Article
Publication: Physics of the Earth and Planetary Interiors
Author(s): Rosat, S.; Gillet, N.
Year: 2023
Formatted Citation: Rosat, S., and N. Gillet, 2023: Intradecadal variations in length of day: Coherence with models of the Earth's core dynamics. Physics of the Earth and Planetary Interiors, 341, 107053, doi:10.1016/j.pepi.2023.107053
Abstract:
Keywords:
ECCO Products Used: KFS
Other URLs:
Qin, Yinghao; Mo, Huier; Wan, Liying; Wang, Yi; Liu, Yang; Yu, Qinglong; Wu, Xiangyu (2023). Heat Budget Analysis for the Extended Development of the 2014-2015 Warming Event, Atmosphere, 6 (14), 954, 10.3390/atmos14060954.
Title: Heat Budget Analysis for the Extended Development of the 2014-2015 Warming Event
Type: Journal Article
Publication: Atmosphere
Author(s): Qin, Yinghao; Mo, Huier; Wan, Liying; Wang, Yi; Liu, Yang; Yu, Qinglong; Wu, Xiangyu
Year: 2023
Formatted Citation: Qin, Y., H. Mo, L. Wan, Y. Wang, Y. Liu, Q. Yu, and X. Wu, 2023: Heat Budget Analysis for the Extended Development of the 2014-2015 Warming Event. Atmosphere, 14(6), 954, doi:10.3390/atmos14060954
Abstract:
In order to figure out the associated underlying dynamical processes of the 2014-2015 warming event, we used the ECCO (Estimating the Circulation and Climate of the Ocean) reanalysis from 1993 to 2016 and two combined scatterometers, QuikSCAT and ASCAT, to analysis hydrodynamic condition and ocean heat budget balance process in the equatorial tropical pacific. The spatiotemporal characteristics of that warming event were revealed by comparing the results with a composite El Niño. The results showed that the significant differences between the 2014 and 2015 warming periods were the magnitudes and positions of the equatorial easterly wind anomalies during the summer months. The abruptly easterly wind anomalies of 2014 that spread across the entire equatorial Pacific triggered the upwelling of the equatorial Kelvin waves and pushed the eastern edge of the warm pool back westward. These combined effects caused abrupt decreases in the sea surface temperatures (SST) and upper ocean heat content (OHC) and damped the 2014 warming process into an El Niño. In addition, the ocean budget of the upper 300 m of the El Niño 3.4 region showed that different dynamical processes were responsible for different warming phases. For example, at the beginning of 2014 and 2015, the U advection and subsurface processes played dominant roles in the positive ocean heat content tendency. During the easterly wind anomalies period of 2014, the U advection process mainly caused a negative tendency and halted the development of the warming phase. In regard to the easterly wind anomalies of 2015, the U advection and subsurface processes were weaker negatively when compared with that in 2014. However, the V advection processes were consistently positive, taking a leading role in the positive trends observed in the middle of 2015.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Li, Mingyu; Shen, Wenbin (2022). Chandler period estimated from frequency domain expression solving the Liouville equation for polar motion, Geophysical Journal International, 2 (231), 1324-1333.
Title: Chandler period estimated from frequency domain expression solving the Liouville equation for polar motion
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Li, Mingyu; Shen, Wenbin
Year: 2022
Formatted Citation: Li, M., and W. Shen, 2022: Chandler period estimated from frequency domain expression solving the Liouville equation for polar motion. Geophysical Journal International, 231(2), 1324-1333, doi:10.1093/gji/ggac256
Abstract: Accurate determination of the Chandler wobble (CW) period (TCW) and quality factor (QCW) is of great significance to our understanding of the Earth's dynamic figure parameters, elasticity, rheology and energy dissipation. TCW and QCW were typically determined in the time domain using the digital filter designed by Wilson; however, we developed an alternative method to estimate TCW in the frequency domain. We adopted the frequency domain expression solving the Liouville equation for polar motion (eq. 3 in the following) rather than the time domain to separate the free-damping CW and excited parts. Next, we substituted various excitation functions derived from the outputs of several general circulation models and selected monthly gravity models into the above frequency domain expression; hence we estimate TCW. The preferred TCW value using this method and the least difference combination mgm90 model is 430.4 ± 2.0 mean solar days. Comparing with previous studies within the error range, our results provide an independent way of estimating TCW.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
He, Yuefan; Nie, Guigen; Wu, Shuguang; Li, Haiyang (2022). Comparative analysis of the correction effect of different environmental loading products on global GNSS coordinate time series, Advances in Space Research, 10.1016/j.asr.2022.08.009.
Title: Comparative analysis of the correction effect of different environmental loading products on global GNSS coordinate time series
Type: Journal Article
Publication: Advances in Space Research
Author(s): He, Yuefan; Nie, Guigen; Wu, Shuguang; Li, Haiyang
Year: 2022
Formatted Citation: He, Y., G. Nie, S. Wu, and H. Li, 2022: Comparative analysis of the correction effect of different environmental loading products on global GNSS coordinate time series. Advances in Space Research, doi:10.1016/j.asr.2022.08.009
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Kenyon, Jennifer An (2022). Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes.
Title: Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes
Type: Thesis
Publication:
Author(s): Kenyon, Jennifer An
Year: 2022
Formatted Citation: Kenyon, J. A., 2022: Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes. https://hdl.handle.net/1721.1/143183.
Abstract: Radioactive isotopes act as nuclear clocks that are utilized to trace and measure rates of chemical, biological, physical, and geological oceanographic processes. This thesis seeks to utilize both artificial (e.g., released from anthropogenic sources) and natural radioisotopes as tracers within the Pacific Ocean basin. Artificial radioisotopes released as a result of the 2011 Fukushima Daiichi nuclear power plants accident have the potential to negatively impact human and environmental health. This study evaluates 137Cs, 90Sr, and 129I concentrations in seawater off the coast of Japan, reconciles the sources of contaminated waters, and assesses the application of 137Cs/90Sr, 129I/137Cs, and 129I/90Sr as oceanic tracers. The analysis of activity ratios suggests a variety of sources, including ongoing sporadic and independent releases of radiocontaminants. Though decreasing, concentrations remain elevated compared to preaccident levels. Future planned releases of stored water from the reactor site may affect the surrounding environment; and thus, continued efforts to understand the distribution and fate of these radionuclides are warranted. Naturally-occurring radioisotopes (e.g., the 238U-234Th series used in this thesis) can give insight into surface export and remineralization of particulate organic carbon (POC) and trace metals (TMs). POC and TMs play a vital role in regulating the biological carbon pump (BCP), which in turn helps to moderate atmospheric CO2 levels by transporting carbon to the deep ocean, where it can be sequestered on timescales of centuries to millennia. Through this thesis we utilize the 238U:234Th disequilibrium method throughout the GEOTRACES GP15 Pacific Meridional Transect in order to provide basin-scale estimates of POC export and remineralization. There is only limited, recent use of this method to constrain TM fluxes, and as such this study also seeks to further develop this method for use in understanding TM cycling through comparative flux studies in the North Pacific.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Zhang, Zhengbei; Wang, Jing; Yuan, Dongliang (2022). Mixed Layer Salinity Balance in the Eastern Tropical Indian Ocean, Journal of Geophysical Research: Oceans, 6 (127), 10.1029/2021JC018229.
Title: Mixed Layer Salinity Balance in the Eastern Tropical Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Zhang, Zhengbei; Wang, Jing; Yuan, Dongliang
Year: 2022
Formatted Citation: Zhang, Z., J. Wang, and D. Yuan, 2022: Mixed Layer Salinity Balance in the Eastern Tropical Indian Ocean. J. Geophys. Res. Ocean., 127(6), doi:10.1029/2021JC018229
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Storto, Andrea; Cheng, Lijing; Yang, Chunxue (2022). Revisiting the 2003-2018 deep-ocean warming through multi-platform analysis of the global energy budget, Journal of Climate, 1-41, 10.1175/JCLI-D-21-0726.1.
Title: Revisiting the 2003-2018 deep-ocean warming through multi-platform analysis of the global energy budget
Type: Journal Article
Publication: Journal of Climate
Author(s): Storto, Andrea; Cheng, Lijing; Yang, Chunxue
Year: 2022
Formatted Citation: Storto, A., L. Cheng, and C. Yang, 2022: Revisiting the 2003-2018 deep-ocean warming through multi-platform analysis of the global energy budget. J. Clim., 1-41, doi:10.1175/JCLI-D-21-0726.1
Abstract: Recent estimates of the global warming rates suggest that approximately 9% of the Earth's excess heat is cumulated in the deep and abyssal oceans (below 2000 m depth) during the last two decades. Such estimates assume stationary trends deducted as long-term rates. In order to reassess the deep ocean warming and potentially shed light on its inter-annual variability, we formulate the balance between the Earth's Energy Imbalance (EEI), the steric sea level and the ocean heat content (OHC), at yearly time scales during the 2003-2018 period, as a variational problem. The solution is achieved through variational minimization, merging together observational data from top-of-atmosphere EEI, inferred from CERES, steric sea level estimates from altimetry minus gravimetry, and upper ocean heat content estimates from in-situ platforms (mostly Argo floats). Global ocean reanalyses provide background error covariances for the OHC analysis. The analysis indicates a 2000m-bottom warming of 0.08 ± 0.04 W m −2 for the period 2003-2018, equal to 13% of the total ocean warming (0.62 ± 0.08 W m −2 ), slightly larger than previous estimates but consistent within the error bars. The analysis provides a fully consistent optimized solution also for the steric sea level and EEI. Moreover, the simultaneous use of the different heat budget observing networks is able to decrease the analysis uncertainty with respect to the observational one, for all observation types and especially for the 0-700m OHC and steric sea level (more than 12% reduction). The sensitivity of the analysis to the choice of the background timeseries is proved insignificant.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chi, Jianwei; Qu, Tangdong; Du, Yan; Qi, Jifeng; Shi, Ping (2021). Ocean salinity indices of interannual modes in the tropical Pacific, Climate Dynamics, 10.1007/s00382-021-05911-9.
Title: Ocean salinity indices of interannual modes in the tropical Pacific
Type: Journal Article
Publication: Climate Dynamics
Author(s): Chi, Jianwei; Qu, Tangdong; Du, Yan; Qi, Jifeng; Shi, Ping
Year: 2021
Formatted Citation: Chi, J., T. Qu, Y. Du, J. Qi, and P. Shi, 2021: Ocean salinity indices of interannual modes in the tropical Pacific, Climate Dynamics, doi: 10.1007/s00382-021-05911-9
Abstract: This study investigates the interannual modes of the tropical Pacific using salinity from observations, ocean reanalysis output and CMIP6 products. Here we propose two indices of sea surface salinity (SSS), a monopole mode and a dipole mode, to identify the El Niño—South Oscillation (ENSO) and its diversity, respectively. The monopole mode is primarily controlled by atmospheric forcing, namely, the enhanced precipitation that induces negative SSS anomalies across nearly the entire tropical Pacific. The dipole mode is mainly forced by oceanic dynamics, with zonal current transporting fresh water from the western fresh pool into the western-central and salty water from the subtropics into the eastern tropical Pacific. Under a global warming condition, an increase in the monopole and dipole mode variance indicates an increase in both the central and eastern Pacific El Niño variability. The increase in central Pacific El Niño variability is largely due to enhanced vertical stratification during global warming in the upper layer, with intensified zonal advection. An eastern Pacific El Niño-like warming pattern contributes to the increase in eastern Pacific El Niño, with enhanced precipitation over the central-eastern tropical Pacific.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Kutoglu, Hakan S.; Becek, Kazimierz (2021). Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone, Remote Sensing, 7 (13), 1242, 10.3390/rs13071242.
Title: Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone
Type: Journal Article
Publication: Remote Sensing
Author(s): Kutoglu, Hakan S.; Becek, Kazimierz
Year: 2021
Formatted Citation: Kutoglu, H. S., and K. Becek, 2021: Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone. Remote Sensing, 13(7), 1242, doi:10.3390/rs13071242
Abstract: The Mediterranean Ridge accretionary complex (MAC) is a product of the convergence of Africa-Europe-Aegean plates. As a result, the region exhibits a continuous mass change (horizontal/vertical movements) that generates earthquakes. Over the last 50 years, approximately 430 earthquakes with M ≥ 5, including 36 M ≥ 6 earthquakes, have been recorded in the region. This study aims to link the ocean bottom deformations manifested through ocean bottom pressure variations with the earthquakes' time series. To this end, we investigated the time series of the ocean bottom pressure (OBP) anomalies derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions. The OBP time series comprises a decreasing trend in addition to 1.02, 1.52, 4.27, and 10.66-year periodic components, which can be explained by atmosphere, oceans, and hydrosphere (AOH) processes, the Earth's pole movement, solar activity, and core-mantle coupling. It can be inferred from the results that the OBP anomalies time series/mass change is linked to a rising trend and periods in the earthquakes' energy time series. Based on this preliminary work, ocean-bottom pressure variation appears to be a promising lead for further research.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Mémin, Anthony; Boy, Jean-Paul; Santamaría-Gómez, Alvaro (2020). Correcting GPS measurements for non-tidal loading, GPS Solutions, 2 (24), 45, 10.1007/s10291-020-0959-3.
Title: Correcting GPS measurements for non-tidal loading
Type: Journal Article
Publication: GPS Solutions
Author(s): Mémin, Anthony; Boy, Jean-Paul; Santamaría-Gómez, Alvaro
Year: 2020
Formatted Citation: Mémin, A., J-P. Boy, and A. Santamaría-Gómez, 2020: Correcting GPS measurements for non-tidal loading, GPS Solutions, 24(2), 45, doi: 10.1007/s10291-020-0959-3
Abstract: Non-tidal loading (NTL) deforms the earth’s surface, adding variability to the coordinates of geodetic sites. Yet, according to the IERS Conventions, there are no recommended surface-mass change models to account for NTL deformation in geodetic position time series. We investigate the NTL signal recorded at 585 GPS stations at different frequency bands, from day to years, by comparing GPS estimated displacements to modeled environmental loading. We used up-to-date and high-resolution (both temporal and spatial) models to account for NTL induced by mass changes in the atmosphere, oceans, and continental hydrology. Vertical land motions variability is reduced on average by up to 20% when correcting the series for non-tidal atmospheric and oceanic loading, employing either barotropic or baroclinic ocean models. We then focus on characterizing the ocean response to air-pressure variations, and we observe that there are no significant differences at seasonal timescales between a barotropic ocean model forced by air pressure and winds and a more classical baroclinic ocean model forced by wind, heat and freshwater fluxes. However, any of these choices further reduces the variability by 5% compared to the classical static inverted barometer ocean response. The variability of the vertical coordinate changes is further reduced by an additional 5% by also correcting for continental hydrology loading, especially at seasonal periods. For horizontal coordinate changes, the variability is reduced by less than 5% after correcting for all studied surface-mass changes.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Lai, Yen Ru; Wang, Lei; Bevis, Michael; Fok, Hok Sum; Alanazi, Abdullah (2020). Truncated Singular Value Decomposition Regularization for Estimating Terrestrial Water Storage Changes Using GPS: A Case Study over Taiwan, Remote Sensing, 23 (12), 3861, 10.3390/rs12233861.
Title: Truncated Singular Value Decomposition Regularization for Estimating Terrestrial Water Storage Changes Using GPS: A Case Study over Taiwan
Type: Journal Article
Publication: Remote Sensing
Author(s): Lai, Yen Ru; Wang, Lei; Bevis, Michael; Fok, Hok Sum; Alanazi, Abdullah
Year: 2020
Formatted Citation: Lai, Y. R., L. Wang, M. Bevis, H. S. Fok, and A. Alanazi, 2020: Truncated Singular Value Decomposition Regularization for Estimating Terrestrial Water Storage Changes Using GPS: A Case Study over Taiwan. Remote Sensing, 12(23), 3861, doi:10.3390/rs12233861
Abstract: It is a typical ill-conditioned problem to invert GPS-measured loading deformations for terrestrial water storage (TWS) changes. While previous studies commonly applied the 2nd-order Tikhonov regularization, we demonstrate the truncated singular value decomposition (TSVD) regularization can also be applied to solve the inversion problem. Given the fact that a regularized estimate is always biased, it is valuable to obtain estimates with different methods for better assessing the uncertainty in the solution. We also show the general cross validation (GCV) can be applied to select the truncation term for the TSVD regularization, producing a solution that minimizes predictive mean-square errors. Analyzing decade-long GPS position time series over Taiwan, we apply the TSVD regularization to estimate mean annual TWS variations for Taiwan. Our results show that the TSVD estimates can sufficiently fit the GPS-measured annual displacements, resulting in randomly distributed displacement residuals with a zero mean and small standard deviation (around 0.1 cm). On the island-wide scale, the GPS-inferred annual TWS variation is consistent with the general seasonal cycle of precipitations. However, on smaller spatial scales, we observe significant differences between the TWS changes estimated by GPS and simulated by GLDAS land surface models in terms of spatiotemporal pattern and magnitude. Based on the results, we discuss some challenges in the characterization of TWS variations using GPS observations over Taiwan.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Sutterley, Tyler C.; Velicogna, Isabella; Hsu, Chia-Wei (2020). Self-Consistent Ice Mass Balance and Regional Sea Level From Time-Variable Gravity, Earth and Space Science, 3 (7), 10.1029/2019EA000860.
Title: Self-Consistent Ice Mass Balance and Regional Sea Level From Time-Variable Gravity
Type: Journal Article
Publication: Earth and Space Science
Author(s): Sutterley, Tyler C.; Velicogna, Isabella; Hsu, Chia-Wei
Year: 2020
Formatted Citation: Sutterley, T. C., I. Velicogna, and C. Hsu, 2020: Self-Consistent Ice Mass Balance and Regional Sea Level From Time-Variable Gravity. Earth and Space Science, 7(3), doi:10.1029/2019EA000860
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4
Other URLs:
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Nastula, Jolanta; Wińska, Małgorzata; Śliwińska, Justyna; Salstein, David (2019). Hydrological signals in polar motion excitation - Evidence after fifteen years of the GRACE mission, Journal of Geodynamics (124), 119-132, 10.1016/j.jog.2019.01.014.
Title: Hydrological signals in polar motion excitation - Evidence after fifteen years of the GRACE mission
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Nastula, Jolanta; Wińska, Małgorzata; Śliwińska, Justyna; Salstein, David
Year: 2019
Formatted Citation: Nastula, J., M. Wińska, J. Śliwińska, and D. Salstein, 2019: Hydrological signals in polar motion excitation - Evidence after fifteen years of the GRACE mission. Journal of Geodynamics, 124, 119-132, doi:10.1016/j.jog.2019.01.014
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Guan, Cong; Hu, Shijian; McPhaden, Michael J.; Wang, Fan; Gao, Shan; Hou, Yinglin (2019). Dipole Structure of Mixed Layer Salinity in Response to El Niño-La Niña Asymmetry in the Tropical Pacific, Geophysical Research Letters, 21 (46), 12165-12172, 10.1029/2019GL084817.
Title: Dipole Structure of Mixed Layer Salinity in Response to El Niño-La Niña Asymmetry in the Tropical Pacific
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Guan, Cong; Hu, Shijian; McPhaden, Michael J.; Wang, Fan; Gao, Shan; Hou, Yinglin
Year: 2019
Formatted Citation: Guan, C., S. Hu, M. J. McPhaden, F. Wang, S. Gao, and Y. Hou, 2019: Dipole Structure of Mixed Layer Salinity in Response to El Niño-La Niña Asymmetry in the Tropical Pacific. Geophys. Res. Lett., 46(21), 12165-12172, doi:10.1029/2019GL084817
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Xi, Hui; Zhang, Zizhan; Lu, Yang (2019). A Quasi-Decadal Oscillation of Sea-Level Variation in the South China Sea, Journal of Coastal Research, 2 (36), 228, 10.2112/JCOASTRES-D-19-00078.1.
Title: A Quasi-Decadal Oscillation of Sea-Level Variation in the South China Sea
Type: Journal Article
Publication: Journal of Coastal Research
Author(s): Xi, Hui; Zhang, Zizhan; Lu, Yang
Year: 2019
Formatted Citation: Xi, H., Z. Zhang, and Y. Lu, 2019: A Quasi-Decadal Oscillation of Sea-Level Variation in the South China Sea. Journal of Coastal Research, 36(2), 228, doi:10.2112/JCOASTRES-D-19-00078.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chang, Le; Tang, He; Yi, Shuang; Sun, Wenke (2019). The Trend and Seasonal Change of Sediment in the East China Sea Detected by GRACE, Geophysical Research Letters, 3 (46), 1250-1258, 10.1029/2018GL081652.
Title: The Trend and Seasonal Change of Sediment in the East China Sea Detected by GRACE
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Chang, Le; Tang, He; Yi, Shuang; Sun, Wenke
Year: 2019
Formatted Citation: Chang, L., H. Tang, S. Yi, and W. Sun, 2019: The Trend and Seasonal Change of Sediment in the East China Sea Detected by GRACE. Geophys. Res. Lett., 46(3), 1250-1258, doi:10.1029/2018GL081652
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Xi, Hui; Zhang, Zizhan; Lu, Yang; Li, Yan (2019). Mass sea level variation in the South China Sea from GRACE, altimetry and model and the connection with ENSO, Advances in Space Research, 1 (64), 117-128, 10.1016/j.asr.2019.03.027.
Title: Mass sea level variation in the South China Sea from GRACE, altimetry and model and the connection with ENSO
Type: Journal Article
Publication: Advances in Space 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: Mass sea level variation in the South China Sea from GRACE, altimetry and model and the connection with ENSO. Advances in Space Research, 64(1), 117-128, doi:10.1016/j.asr.2019.03.027
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Xu, Xinyu; Ding, Hao; Zhao, Yongqi; Li, Jin; Hu, Minzhang (2019). GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake, Remote Sensing, 11 (11), 1295, 10.3390/rs11111295.
Title: GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake
Type: Journal Article
Publication: Remote Sensing
Author(s): Xu, Xinyu; Ding, Hao; Zhao, Yongqi; Li, Jin; Hu, Minzhang
Year: 2019
Formatted Citation: Xu, X., H. Ding, Y. Zhao, J. Li, and M. Hu, 2019: GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake. Remote Sensing, 11(11), 1295, doi:10.3390/rs11111295
Abstract: In contrast to most of the coseismic gravity change studies, which are generally based on data from the Gravity field Recovery and Climate Experiment (GRACE) satellite mission, we use observations from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) Satellite Gravity Gradient (SGG) mission to estimate the coseismic gravity and gravity gradient changes caused by the 2011 Tohoku-Oki Mw 9.0 earthquake. We first construct two global gravity field models up to degree and order 220, before and after the earthquake, based on the least-squares method, with a bandpass Auto Regression Moving Average (ARMA) filter applied to the SGG data along the orbit. In addition, to reduce the influences of colored noise in the SGG data and the polar gap problem on the recovered model, we propose a tailored spherical harmonic (TSH) approach, which only uses the spherical harmonic (SH) coefficients with the degree range 30-95 to compute the coseismic gravity changes in the spatial domain. Then, both the results from the GOCE observations and the GRACE temporal gravity field models (with the same TSH degrees and orders) are simultaneously compared with the forward-modeled signals that are estimated based on the fault slip model of the earthquake event. Although there are considerable misfits between GOCE-derived and modeled gravity gradient changes (ΔVxx, ΔVyy, ΔVzz, and ΔVxz), we find analogous spatial patterns and a significant change (greater than 3σ) in gravity gradients before and after the earthquake. Moreover, we estimate the radial gravity gradient changes from the GOCE-derived monthly time-variable gravity field models before and after the earthquake, whose amplitudes are at a level over three times that of their corresponding uncertainties, and are thus significant. Additionally, the results show that the recovered coseismic gravity signals in the west-to-east direction from GOCE are closer to the modeled signals than those from GRACE in the TSH degree range 30-95. This indicates that the GOCE-derived gravity models might be used as additional observations to infer/explain some time-variable geophysical signals of interest.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Sun, Qiwei; Du, Yan; Zhang, Yuhong; Feng, Ming; Chowdary, Jasti S.; Chi, Jianwei; Qiu, Shuang; Yu, Weidong (2019). Evolution of Sea Surface Salinity Anomalies in the Southwestern Tropical Indian Ocean During 2010-2011 Influenced by a Negative IOD Event, Journal of Geophysical Research: Oceans, 5 (124), 3428-3445, 10.1029/2018JC014580.
Title: Evolution of Sea Surface Salinity Anomalies in the Southwestern Tropical Indian Ocean During 2010-2011 Influenced by a Negative IOD Event
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Sun, Qiwei; Du, Yan; Zhang, Yuhong; Feng, Ming; Chowdary, Jasti S.; Chi, Jianwei; Qiu, Shuang; Yu, Weidong
Year: 2019
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Sutterley, Tyler C.; Velicogna, Isabella (2019). Improved Estimates of Geocenter Variability from Time-Variable Gravity and Ocean Model Outputs, Remote Sensing, 18 (11), 2108, 10.3390/rs11182108.
Title: Improved Estimates of Geocenter Variability from Time-Variable Gravity and Ocean Model Outputs
Type: Journal Article
Publication: Remote Sensing
Author(s): Sutterley, Tyler C.; Velicogna, Isabella
Year: 2019
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4
Other URLs:
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
Keywords: Earth tides, atmosphere, gravity observations, hydrology, nontidal ocean loading
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
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.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chen, Jianli; Wilson, Clark R.; Kuang, Weijia; Chao, Benjamin F. (2019). Interannual Oscillations in Earth Rotation, Journal of Geophysical Research: Solid Earth, 12 (124), 13404-13414, 10.1029/2019JB018541.
Title: Interannual Oscillations in Earth Rotation
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Chen, Jianli; Wilson, Clark R.; Kuang, Weijia; Chao, Benjamin F.
Year: 2019
Formatted Citation: Chen, J., C. R. Wilson, W. Kuang, and B. F. Chao, 2019: Interannual Oscillations in Earth Rotation. Journal of Geophysical Research: Solid Earth, 124(12), 13404-13414, doi:10.1029/2019JB018541
Abstract:
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ECCO Products Used: ECCO-KFS
Other URLs:
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Storto, Andrea; Bonaduce, Antonio; Feng, Xiangbo; Yang, Chunxue (2019). Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales, Water, 10 (11), 1987, 10.3390/w11101987.
Title: Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales
Type: Journal Article
Publication: Water
Author(s): Storto, Andrea; Bonaduce, Antonio; Feng, Xiangbo; Yang, Chunxue
Year: 2019
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4
Other URLs:
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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, 4 (11), 1501-1513, 10.5194/essd-11-1501-2019.
Title: Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata
Type: Journal Article
Publication: Earth System Science Data
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: Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata. Earth System Science Data, 11(4), 1501-1513, doi:10.5194/essd-11-1501-2019
Abstract: The Argentine-German Geodetic Observatory (AGGO) is one of the very few sites in the Southern Hemisphere equipped with comprehensive cutting-edge geodetic instrumentation. The employed observation techniques are used for a wide range of geophysical applications. The 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 (World Meteorological Organization) sites where data are 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).
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Klein, E.; Duputel, Z.; Zigone, D.; Vigny, C.; Boy, J.-P.; Doubre, C.; Meneses, G. (2018). Deep Transient Slow Slip Detected by Survey GPS in the Region of Atacama, Chile, Geophysical Research Letters, 22 (45), 12,263-12,273, 10.1029/2018GL080613.
Title: Deep Transient Slow Slip Detected by Survey GPS in the Region of Atacama, Chile
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Klein, E.; Duputel, Z.; Zigone, D.; Vigny, C.; Boy, J.-P.; Doubre, C.; Meneses, G.
Year: 2018
Formatted Citation: Klein, E., Z. Duputel, D. Zigone, C. Vigny, J.-P. Boy, C. Doubre, and G. Meneses, 2018: Deep Transient Slow Slip Detected by Survey GPS in the Region of Atacama, Chile, Geophysical Research Letters, 45(22), 12,263-12,273, doi: 10.1029/2018GL080613
Abstract: We detected a long-term transient deformation signal between 2014 and 2016 in the Atacama region (Chile) using survey Global Positioning System (GPS) observations. Over an ~150 km along-strike region, survey GPS measurements in 2014 and 2016 deviate significantly from the interseismic trend estimated using previous observations. This deviation from steady state deformation is spatially coherent and reveals a horizontal westward diverging motion of several centimeters, along with a significant uplift. It is confirmed by continuous measurements of recently installed GPS stations. We discard instrumental, hydrological, oceanic, or atmospheric loading effects and show that the transient is likely due to deep slow slip in the transition zone of the subduction interface (~40- to 60-km depth). In addition, daily observations recorded by a continuous GPS station operating between 2002 and 2015 highlight similar transient signals in 2005 and 2009, suggesting a recurrent pattern.
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ECCO Products Used: ECCO-KFS
Other URLs:
Wei, Na; Shi, Chuang; Wang, Guangxing; Liu, Jingnan (2018). Improved estimations of low-degree coefficients using GPS displacements with reduced non-loading errors, Geophysical Journal International, 2 (212), 1274-1287, 10.1093/gji/ggx357.
Title: Improved estimations of low-degree coefficients using GPS displacements with reduced non-loading errors
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Wei, Na; Shi, Chuang; Wang, Guangxing; Liu, Jingnan
Year: 2018
Formatted Citation: Wei, N., C. Shi, G. Wang, and J. Liu, 2018: Improved estimations of low-degree coefficients using GPS displacements with reduced non-loading errors. Geophysical Journal International, 212(2), 1274-1287, doi:10.1093/gji/ggx357
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Yu, Nan; Li, Jiancheng; Ray, Jim; Chen, Wei (2018). Improved geophysical excitation of length-of-day constrained by Earth orientation parameters and satellite gravimetry products, Geophysical Journal International, 3 (214), 1633-1651, 10.1093/gji/ggy204.
Title: Improved geophysical excitation of length-of-day constrained by Earth orientation parameters and satellite gravimetry products
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Yu, Nan; Li, Jiancheng; Ray, Jim; Chen, Wei
Year: 2018
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.
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ECCO Products Used: ECCO-KFS
Other URLs:
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.
Title: Upper Ocean Four-Dimensional Variational Data Assimilation in the Arabian Sea and Bay of Bengal
Type: Journal Article
Publication: Marine Geodesy
Author(s): Dwivedi, Suneet; Srivastava, Atul; Mishra, Alok Kumar
Year: 2018
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
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.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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.
Title: Terrestrial water storage variations and their effect on polar motion
Type: Journal Article
Publication: Acta Geophysica
Author(s): Śliwińska, Justyna; Wińska, Małgorzata; Nastula, Jolanta
Year: 2018
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Watkins, Andrew (2017). Earth Rotation and Deformation Signals Caused by Deep Earth Processes, Bowling Green State University, 58.
Title: Earth Rotation and Deformation Signals Caused by Deep Earth Processes
Type: Thesis
Publication: Bowling Green State University
Author(s): Watkins, Andrew
Year: 2017
Formatted Citation: Watkins, A., 2017, Earth Rotation and Deformation Signals Caused by Deep Earth Processes, Bowling Green State University, 58
Abstract: The length of a day on Earth (abbreviated LOD) is not exactly 24 hours. There is a small excess LOD that varies on timescales ranging from a few days to thousands of years, generally on the order of milliseconds. One characteristic of LOD variations is a sinusoidal component with a period of ~6 years. The cause of the ~6-year signal is unknown, but is generally suspected to be exchanges of angular momentum between the mantle and the core. This study aimed to test the hypothesis that the ~6-year LOD signal is due to coupling between the mantle and fluid outer core. The flow of the core's fluid deforms the base of the mantle, leading to redistribution of Earth's mass (causing changes in the gravitational field) and deformation of the overlying crust. Surface deformation data from a global network of high-precision Global Positioning System (GPS) stations was analyzed, and the component that acts on the ~6-year timescale was isolated and inverted for the core's flow. Resulting angular momentum changes were computed for the outer core and compared to the LOD signal to search for evidence of core-mantle coupling. Outer core angular momentum changes obtained from GPS deformation data exhibit evidence of the suspected core-mantle coupling, but this result is sensitive to inversion parameters. Changes in the gravitational field were also modeled and found to be smaller than the errors in the currently available data.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Compton, Kathleen; Bennett, Richard A.; Hreinsdóttir, Sigrún; van Dam, Tonie; Bordoni, Andrea; Barletta, Valentina; Spada, Giorgio (2017). Short-term variations of Icelandic ice cap mass inferred from cGPS coordinate time series, Geochemistry, Geophysics, Geosystems, 6 (18), 2099-2119, 10.1002/2017GC006831.
Title: Short-term variations of Icelandic ice cap mass inferred from cGPS coordinate time series
Type: Journal Article
Publication: Geochemistry, Geophysics, Geosystems
Author(s): Compton, Kathleen; Bennett, Richard A.; Hreinsdóttir, Sigrún; van Dam, Tonie; Bordoni, Andrea; Barletta, Valentina; Spada, Giorgio
Year: 2017
Formatted Citation: Compton, K., R. A. Bennett, S. Hreinsdóttir, T. van Dam, A. Bordoni, V. Barletta, and G. Spada, 2017: Short-term variations of Icelandic ice cap mass inferred from cGPS coordinate time series. Geochemistry, Geophysics, Geosystems, 18(6), 2099-2119, doi:10.1002/2017GC006831
Abstract:
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ECCO Products Used: ECCO-KFS
Other URLs:
Liu, Lin; Khan, Shfaqat Abbas; van Dam, Tonie; Ma, Joseph Ho Yin; Bevis, Michael (2017). Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading, Journal of Geophysical Research: Solid Earth, 1 (122), 677-691, 10.1002/2016JB013494.
Title: Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Liu, Lin; Khan, Shfaqat Abbas; van Dam, Tonie; Ma, Joseph Ho Yin; Bevis, Michael
Year: 2017
Formatted Citation: Liu, L., S. A. Khan, T. van Dam, J. H. Y. Ma, and M. Bevis, 2017: Annual variations in GPS-measured vertical displacements near Upernavik Isstrøm (Greenland) and contributions from surface mass loading. Journal of Geophysical Research: Solid Earth, 122(1), 677-691, doi:10.1002/2016JB013494
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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.
Title: Trends and interannual variability of mass and steric sea level in the Tropical Asian Seas
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Kleinherenbrink, Marcel; Riva, Riccardo; Frederikse, Thomas; Merrifield, Mark; Wada, Yoshihide
Year: 2017
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4
Other URLs:
Storto, Andrea; Masina, Simona; Balmaseda, Magdalena; Guinehut, Stéphanie; Xue, Yan; Szekely, Tanguy; Fukumori, Ichiro; Forget, Gael; Chang, You-Soon; Good, Simon A; Köhl, Armin; Vernieres, Guillaume; Ferry, Nicolas; Peterson, K Andrew; Behringer, David; Ishii, Masayoshi; Masuda, Shuhei; Fujii, Yosuke; Toyoda, Takahiro; Yin, Yonghong; Valdivieso, Maria; Barnier, Bernard; Boyer, Tim; Lee, Tony; Gourrion, Jérome; Wang, Ou; Heimbach, Patrick; Rosati, Anthony; Kovach, Robin; Hernandez, Fabrice; Martin, Matthew J; Kamachi, Masafumi; Kuragano, Tsurane; Mogensen, Kristian; Alves, Oscar; Haines, Keith; Wang, Xiaochun (2017). Steric sea level variability (1993-2010) in an ensemble of ocean reanalyses and objective analyses, Climate Dynamics, 3 (49), 709-729, 10.1007/s00382-015-2554-9.
Title: Steric sea level variability (1993-2010) in an ensemble of ocean reanalyses and objective analyses
Type: Journal Article
Publication: Climate Dynamics
Author(s): Storto, Andrea; Masina, Simona; Balmaseda, Magdalena; Guinehut, Stéphanie; Xue, Yan; Szekely, Tanguy; Fukumori, Ichiro; Forget, Gael; Chang, You-Soon; Good, Simon A; Köhl, Armin; Vernieres, Guillaume; Ferry, Nicolas; Peterson, K Andrew; Behringer, David; Ishii, Masayoshi; Masuda, Shuhei; Fujii, Yosuke; Toyoda, Takahiro; Yin, Yonghong; Valdivieso, Maria; Barnier, Bernard; Boyer, Tim; Lee, Tony; Gourrion, Jérome; Wang, Ou; Heimbach, Patrick; Rosati, Anthony; Kovach, Robin; Hernandez, Fabrice; Martin, Matthew J; Kamachi, Masafumi; Kuragano, Tsurane; Mogensen, Kristian; Alves, Oscar; Haines, Keith; Wang, Xiaochun
Year: 2017
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4;GECCO2
Other URLs:
Toyoda, Takahiro; Fujii, Yosuke; Kuragano, Tsurane; Kamachi, Masafumi; Ishikawa, Yoichi; Masuda, Shuhei; Sato, Kanako; Awaji, Toshiyuki; Hernandez, Fabrice; Ferry, Nicolas; Guinehut, Stéphanie; Martin, Matthew J; Peterson, K Andrew; Good, Simon A; Valdivieso, Maria; Haines, Keith; Storto, Andrea; Masina, Simona; Köhl, Armin; Zuo, Hao; Balmaseda, Magdalena; Yin, Yonghong; Shi, Li; Alves, Oscar; Smith, Gregory; Chang, You-Soon; Vernieres, Guillaume; Wang, Xiaochun; Forget, Gael; Heimbach, Patrick; Wang, Ou; Fukumori, Ichiro; Lee, Tong (2017). Intercomparison and validation of the mixed layer depth fields of global ocean syntheses, Climate Dynamics, 3 (49), 753-773, 10.1007/s00382-015-2637-7.
Title: Intercomparison and validation of the mixed layer depth fields of global ocean syntheses
Type: Journal Article
Publication: Climate Dynamics
Author(s): Toyoda, Takahiro; Fujii, Yosuke; Kuragano, Tsurane; Kamachi, Masafumi; Ishikawa, Yoichi; Masuda, Shuhei; Sato, Kanako; Awaji, Toshiyuki; Hernandez, Fabrice; Ferry, Nicolas; Guinehut, Stéphanie; Martin, Matthew J; Peterson, K Andrew; Good, Simon A; Valdivieso, Maria; Haines, Keith; Storto, Andrea; Masina, Simona; Köhl, Armin; Zuo, Hao; Balmaseda, Magdalena; Yin, Yonghong; Shi, Li; Alves, Oscar; Smith, Gregory; Chang, You-Soon; Vernieres, Guillaume; Wang, Xiaochun; Forget, Gael; Heimbach, Patrick; Wang, Ou; Fukumori, Ichiro; Lee, Tong
Year: 2017
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4;GECCO2
Other URLs:
Chen, Wei; Li, Jiancheng; Ray, Jim; Cheng, Minkang (2017). Improved geophysical excitations constrained by polar motion observations and GRACE/SLR time-dependent gravity, Geodesy and Geodynamics, 6 (8), 377-388, 10.1016/j.geog.2017.04.006.
Title: Improved geophysical excitations constrained by polar motion observations and GRACE/SLR time-dependent gravity
Type: Journal Article
Publication: Geodesy and Geodynamics
Author(s): Chen, Wei; Li, Jiancheng; Ray, Jim; Cheng, Minkang
Year: 2017
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
ECCO Products Used: ECCO-KFS
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 μas (17 μas/d).
Keywords: Earth rotation, GNSS VLBI SLR DORIS, Kalman filter, Terrestrial Reference Frames, geocenter motion, time series
ECCO Products Used: ECCO-KFS
Other URLs:
Toyoda, Takahiro; Fujii, Yosuke; Kuragano, Tsurane; Kosugi, Naohiro; Sasano, Daisuke; Kamachi, Masafumi; Ishikawa, Yoichi; Masuda, Shuhei; Sato, Kanako; Awaji, Toshiyuki; Hernandez, Fabrice; Ferry, Nicolas; Guinehut, Stéphanie; Martin, Matthew; Andrew Peterson, K; Good, Simon A; Valdivieso, Maria; Haines, Keith; Storto, Andrea; Masina, Simona; Köhl, Armin; Yin, Yonghong; Shi, Li; Alves, Oscar; Smith, Gregory; Chang, You-Soon; Vernieres, Guillaume; Wang, Xiaochun; Forget, Gael; Heimbach, Patrick; Wang, Ou; Fukumori, Ichiro; Lee, Tong; Zuo, Hao; Balmaseda, Magdalena (2017). Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses, Climate Dynamics, 3 (49), 891-907, 10.1007/s00382-015-2762-3.
Title: Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses
Type: Journal Article
Publication: Climate Dynamics
Author(s): Toyoda, Takahiro; Fujii, Yosuke; Kuragano, Tsurane; Kosugi, Naohiro; Sasano, Daisuke; Kamachi, Masafumi; Ishikawa, Yoichi; Masuda, Shuhei; Sato, Kanako; Awaji, Toshiyuki; Hernandez, Fabrice; Ferry, Nicolas; Guinehut, Stéphanie; Martin, Matthew; Andrew Peterson, K; Good, Simon A; Valdivieso, Maria; Haines, Keith; Storto, Andrea; Masina, Simona; Köhl, Armin; Yin, Yonghong; Shi, Li; Alves, Oscar; Smith, Gregory; Chang, You-Soon; Vernieres, Guillaume; Wang, Xiaochun; Forget, Gael; Heimbach, Patrick; Wang, Ou; Fukumori, Ichiro; Lee, Tong; Zuo, Hao; Balmaseda, Magdalena
Year: 2017
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.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4;GECCO2
Other URLs:
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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
ECCO Products Used: ECCO-KFS
Other URLs: http://www.sciencedirect.com/science/article/pii/S0924796316303323
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. (2017). Ocean heat content variability and change in an ensemble of ocean reanalyses, Climate Dynamics, 3 (49), 909-930, 10.1007/s00382-015-2801-0.
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
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4
Other URLs:
Sun, Yu; Riva, Riccardo; Ditmar, Pavel (2016). Optimizing estimates of annual variations and trends in geocenter motion and J 2 from a combination of GRACE data and geophysical models, Journal of Geophysical Research: Solid Earth, 11 (121), 8352-8370, 10.1002/2016JB013073.
Title: Optimizing estimates of annual variations and trends in geocenter motion and J 2 from a combination of GRACE data and geophysical models
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Sun, Yu; Riva, Riccardo; Ditmar, Pavel
Year: 2016
Formatted Citation: Sun, Y., R. Riva, and P. Ditmar, 2016: Optimizing estimates of annual variations and trends in geocenter motion and J 2 from a combination of GRACE data and geophysical models. Journal of Geophysical Research: Solid Earth, 121(11), 8352-8370, doi:10.1002/2016JB013073
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Mikolaj, M.; Meurers, B.; Güntner, A. (2016). Modelling of global mass effects in hydrology, atmosphere and oceans on surface gravity, Computers & Geosciences (93), 12-20, 10.1016/j.cageo.2016.04.014.
Title: Modelling of global mass effects in hydrology, atmosphere and oceans on surface gravity
Type: Journal Article
Publication: Computers & Geosciences
Author(s): Mikolaj, M.; Meurers, B.; Güntner, A.
Year: 2016
Formatted Citation: Mikolaj, M., B. Meurers, and A. Güntner, 2016: Modelling of global mass effects in hydrology, atmosphere and oceans on surface gravity. Computers & Geosciences, 93, 12-20, doi:10.1016/j.cageo.2016.04.014
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Save, Himanshu; Bettadpur, Srinivas; Tapley, Byron D. (2016). High-resolution CSR GRACE RL05 mascons, Journal of Geophysical Research: Solid Earth, 10 (121), 7547-7569, 10.1002/2016JB013007.
Title: High-resolution CSR GRACE RL05 mascons
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Save, Himanshu; Bettadpur, Srinivas; Tapley, Byron D.
Year: 2016
Formatted Citation: Save, H., S. Bettadpur, and B. D. Tapley, 2016: High-resolution CSR GRACE RL05 mascons. Journal of Geophysical Research: Solid Earth, 121(10), 7547-7569, doi:10.1002/2016JB013007
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Srivastava, Atul; Dwivedi, Suneet; Mishra, Alok Kumar (2016). Intercomparison of High-Resolution Bay of Bengal Circulation Models Forced with Different Winds, Marine Geodesy, 3-4 (39), 271-289, 10.1080/01490419.2016.1173606.
Title: Intercomparison of High-Resolution Bay of Bengal Circulation Models Forced with Different Winds
Type: Journal Article
Publication: Marine Geodesy
Author(s): Srivastava, Atul; Dwivedi, Suneet; Mishra, Alok Kumar
Year: 2016
Formatted Citation: Srivastava, A., S. Dwivedi, and A. K. Mishra, 2016: Intercomparison of High-Resolution Bay of Bengal Circulation Models Forced with Different Winds. Marine Geodesy, 39(3-4), 271-289, doi:10.1080/01490419.2016.1173606
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Brzeziński, Aleksander; Jóźwik, Mieczysław; Kaczorowski, Marek; Kalarus, Maciej; Kasza, Damian; Kosek, Wiesław; Nastula, Jolanta; Szczerbowski, Zbigniew; Wińska, Małgorzata; Wronowski, Roman; Zdunek, Ryszard; Zieliński, Janusz B. (2016). Geodynamic Research at the Department of Planetary Geodesy, SRC PAS, Reports on Geodesy and Geoinformatics, 1 (100), 131-147, 10.1515/rgg-2016-0011.
Title: Geodynamic Research at the Department of Planetary Geodesy, SRC PAS
Type: Journal Article
Publication: Reports on Geodesy and Geoinformatics
Author(s): Brzeziński, Aleksander; Jóźwik, Mieczysław; Kaczorowski, Marek; Kalarus, Maciej; Kasza, Damian; Kosek, Wiesław; Nastula, Jolanta; Szczerbowski, Zbigniew; Wińska, Małgorzata; Wronowski, Roman; Zdunek, Ryszard; Zieliński, Janusz B.
Year: 2016
Formatted Citation: Brzeziński, A. and Coauthors, 2016: Geodynamic Research at the Department of Planetary Geodesy, SRC PAS. Reports on Geodesy and Geoinformatics, 100(1), 131-147, doi:10.1515/rgg-2016-0011
Abstract: The Department of Planetary Geodesy of the Space Research Centre PAS has been conducting research on a broad spectrum of problems within a field of global dynamics of the Earth. In this report we describe the investigations on selected subjects concerning polar motion (modeling and geophysical interpretation of the Chandler wobble, hydrological excitation of seasonal signals, search for optimal prediction methods), tectonic activity in the region of the Książ Geodynamic Laboratory of the SRC, and finally the new joint Polish-Italian project GalAc analyzing feasibility and usefulness of equipping second-generation Galileo satellites with accelerometers.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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.
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ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Nie, Xunwei; Gao, Shan; Wang, Fan; Qu, Tangdong (2016). Subduction of North Pacific Tropical Water and its equatorward pathways as shown by a simulated passive tracer, Journal of Geophysical Research: Oceans, 12 (121), 8770-8786, 10.1002/2016JC012305.
Title: Subduction of North Pacific Tropical Water and its equatorward pathways as shown by a simulated passive tracer
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Nie, Xunwei; Gao, Shan; Wang, Fan; Qu, Tangdong
Year: 2016
Formatted Citation: Nie, X., S. Gao, F. Wang, and T. Qu, 2016: Subduction of North Pacific Tropical Water and its equatorward pathways as shown by a simulated passive tracer. J. Geophys. Res. Ocean., 121(12), 8770-8786, doi:10.1002/2016JC012305
Abstract: This study investigates the subduction of South Pacific Tropical Water (SPTW) and its equatorward pathways using a simulated passive tracer of the consortium Estimating the Circulation & Climate of the Ocean (ECCO). The results show that approximately 5.8 Sv (1 Sv [ 106m3 s-1) of the SPTW is formed in the subtropical South Pacific Ocean within the density range between 24.0 and 25.0 kgm-3, of which about 87% is due to vertical pumping and 13% is due to lateral induction, comparing reasonably well with estimates from climatological data. Once subducted, most SPTW spreads in the subtropical South Pacific. Because of the presence of mixing, some portion of the water is transformed, and its tracer-weighted density steadily increases from an initial value of 24.4 to nearly 25.0 kgm-3 after 13 years of integration. Approximately 42% of the water makes its way into the equatorial Pacific, either through the western boundary or interior pathway. The two equatorward pathways are essentially of equal importance. A large (~70%) portion of the SPTW entering the equatorial region resurfaces in the central equatorial Pacific. The potential impacts of the resurfacing SPTW on the equatorial thermocline and surface stratification are discussed. © 2013 American Meteorological Society.
Keywords: 4255 Numerical modeling, 4283 Water masses, 4572 Upper ocean and mixed layer processes, 4576 Western boundary currents, North Pacific Tropical Water, mixing, pathway, resurface, subduction
ECCO Products Used: ECCO-KFS
Other URLs: https://doi.org/10.1002/2016JC012305
Li, Weiwei; van Dam, Tonie; Li, Zhao; Shen, Yunzhong (2016). Annual variation detected by GPS, GRACE and loading models, Studia Geophysica et Geodaetica, 4 (60), 608-621, 10.1007/s11200-016-0205-1.
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.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
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:
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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
ECCO Products Used: ECCO-KFS
Other URLs:
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.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Wińska, Małgorzata; Nastula, Jolanta; Kołaczek, Barbara (2016). Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion, Acta Geophysica, 1 (64), 270-292, 10.1515/acgeo-2015-0041.
Title: Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion
Type: Journal Article
Publication: Acta Geophysica
Author(s): Wińska, Małgorzata; Nastula, Jolanta; Kołaczek, Barbara
Year: 2016
Formatted Citation: Wińska, M., J. Nastula, and B. Kołaczek, 2016: Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion. Acta Geophysica, 64(1), 270-292, doi:10.1515/acgeo-2015-0041
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Bonin, J. A.; Chambers, D. P. (2015). Quantifying the resolution level where the GRACE satellites can separate Greenland’s glacial mass balance from surface mass balance, The Cryosphere, 5 (9), 1761-1772, 10.5194/tc-9-1761-2015.
Title: Quantifying the resolution level where the GRACE satellites can separate Greenland’s glacial mass balance from surface mass balance
Type: Journal Article
Publication: The Cryosphere
Author(s): Bonin, J. A.; Chambers, D. P.
Year: 2015
Formatted Citation: Bonin, J. A., and D. P. Chambers, 2015: Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance. Cryosph., 9(5), 1761-1772, doi:10.5194/tc-9-1761-2015
Abstract: Mass change over Greenland can be caused by either changes in the glacial dynamic mass balance (DMB) or the surface mass balance (SMB). The GRACE satellite gravity mission cannot directly separate the two physical causes because it measures the sum of the entire mass column with limited spatial resolution. We demonstrate one theoretical way to indirectly separate cumulative SMB from DMB with GRACE, using a least squares inversion technique with knowledge of the location of the glaciers. However, we find that the limited 60 × 60 spherical harmonic representation of current GRACE data does not provide sufficient resolution to adequately accomplish the task. We determine that at a maximum degree/order of 90 × 90 or above, a noise-free gravity measurement could theoretically separate the SMB from DMB signals. However, current GRACE satellite errors are too large at present to separate the signals. A noise reduction of a factor of 10 at a resolution of 90 × 90 would provide the accuracy needed for the interannual cumulative SMB and DMB to be accurately separated.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Makowski, Jessica K.; Chambers, Don P.; Bonin, Jennifer A. (2015). Using ocean bottom pressure from the gravity recovery and climate experiment (GRACE) to estimate transport variability in the southern Indian Ocean, Journal of Geophysical Research: Oceans, 6 (120), 4245-4259, 10.1002/2014JC010575.
Title: Using ocean bottom pressure from the gravity recovery and climate experiment (GRACE) to estimate transport variability in the southern Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Makowski, Jessica K.; Chambers, Don P.; Bonin, Jennifer A.
Year: 2015
Formatted Citation: Makowski, J. K., D. P. Chambers, and J. A. Bonin, 2015: Using ocean bottom pressure from the gravity recovery and climate experiment (GRACE) to estimate transport variability in the southern I ndian O cean. J. Geophys. Res. Ocean., 120(6), 4245-4259, doi:10.1002/2014JC010575
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Ron, Cyril; Vondrák, Jan; Chapanov, Yavor (2015). Atmospheric, oceanic and geomagnetic excitation of nutation, Proceedings of the IX Bulgarian-Serbian Astronomical Conference: Astroinformatics (IX BSACA), 15, 127-135.
Title: Atmospheric, oceanic and geomagnetic excitation of nutation
Type: Conference Proceedings
Publication: Proceedings of the IX Bulgarian-Serbian Astronomical Conference: Astroinformatics (IX BSACA)
Author(s): Ron, Cyril; Vondrák, Jan; Chapanov, Yavor
Year: 2015
Formatted Citation: Ron, C., J. Vondrák, and Y. Chapanov, 2015: Atmospheric, oceanic and geomagnetic excitation of nutation. Proceedings of the IX Bulgarian-Serbian Astronomical Conference: Astroinformatics (IX BSACA), M. K. Tsvetkov, M. S. Dimitrijević, O. Kounchev, D. Jevremović, and K. Tsvetkova, Eds. Astron. Soc. "Rudjer Bošković", Sofia, Bulgaria(15), 127-135 pp.
Abstract: We tested the hypothesis of Malkin (2013), who recently demonstrated that the observed changes of Free Core Nutation parameters (phase, amplitude) occur near the epochs of geomagnetic jerks (rapid changes of the secular variations of geomagnetic field). We found that if the numerical integration of Brzezinski broad-band Liouville equations of atmo- spheric/oceanic excitations is re-initialized at the epochs of geomagnetic jerks, the agreement between the integrated and observed celestial pole offsets is improved (Vondrák & Ron 2014). Nevertheless, this approach assumes that the influence of geomagnetic jerks leads to a stepwise change in the position of celestial pole, which is physically not acceptable. Therefore we in- troduce a simple continuous excitation function that hypothetically describes the influence of geomagnetic jerks, and leads to rapid but continuous changes of pole position. The results of numerical integration of atmospheric/oceanic excitations plus this newly introduced excitation are then compared with the observed celestial pole offsets, and prove that the agreement is improved significantly.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: http://elibrary.matf.bg.ac.rs/bitstream/handle/123456789/4188/17.pdf?sequence=1, http://elibrary.matf.bg.ac.rs/handle/123456789/4188
Göttl, F.; Schmidt, M.; Seitz, F.; Bloßfeld, M. (2015). Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations, Journal of Geodesy, 4 (89), 377-390, 10.1007/s00190-014-0782-0.
Title: Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Göttl, F.; Schmidt, M.; Seitz, F.; Bloßfeld, M.
Year: 2015
Formatted Citation: Göttl, F., M. Schmidt, F. Seitz, and M. Bloßfeld, 2015: Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations. Journal of Geodesy, 89(4), 377-390, doi:10.1007/s00190-014-0782-0
Abstract: The goal of our study is to determine accurate time series of geophysical Earth rotation excitations to learn more about global dynamic processes in the Earth system. For this purpose, we developed an adjustment model which allows to combine precise observations from space geodetic observation systems, such as Satellite Laser Ranging (SLR), Global Navigation Satellite Systems, Very Long Baseline Interferometry, Doppler Orbit determination and Radiopositioning Integrated on Satellite, satellite altimetry and satellite gravimetry in order to separate geophysical excitation mechanisms of Earth rotation. Three polar motion time series are applied to derive the polar motion excitation functions (integral effect). Furthermore we use five time variable gravity field solutions from Gravity Recovery and Climate Experiment to determine not only the integral mass effect but also the oceanic and hydrological mass effects by applying suitable filter techniques and a land-ocean mask. For comparison the integral mass effect is also derived from degree 2 potential coefficients that are estimated from SLR observations. The oceanic mass effect is also determined from sea level anomalies observed by satellite altimetry by reducing the steric sea level anomalies derived from temperature and salinity fields of the oceans. Due to the combination of all geodetic estimated excitations the weaknesses of the individual processing strategies can be reduced and the technique-specific strengths can be accounted for. The formal errors of the adjusted geodetic solutions are smaller than the RMS differences of the geophysical model solutions. The improved excitation time series can be used to improve the geophysical modeling.
Keywords: Combination of geodetic space observations, Polar motion excitation functions, Separation of individual mass and motion effects
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Yan, C X; Zhu, J; Xie, J P (2015). An ocean data assimilation system in the Indian Ocean and west Pacific Ocean, Advances in Atmospheric Sciences, 11 (32), 1460-1472, 10.1007/s00376-015-4121-z.
Title: An ocean data assimilation system in the Indian Ocean and west Pacific Ocean
Type: Journal Article
Publication: Advances in Atmospheric Sciences
Author(s): Yan, C X; Zhu, J; Xie, J P
Year: 2015
Formatted Citation: Yan, C. X., J. Zhu, and J. P. Xie, 2015: An ocean data assimilation system in the Indian Ocean and west Pacific Ocean. Advances in Atmospheric Sciences, 32(11), 1460-1472, doi:10.1007/s00376-015-4121-z
Abstract: The development and application of a regional ocean data assimilation system are among the aims of the Global Ocean Data Assimilation Experiment. The ocean data assimilation system in the regions including the Indian and West Pacific oceans is an endeavor motivated by this goal. In this study, we describe the system in detail. Moreover, the reanalysis in the joint area of Asia, the Indian Ocean, and the western Pacific Ocean (hereafter AIPOcean) constructed using multi-year model integration with data assimilation is used to test the performance of this system. The ocean model is an eddy-resolving, hybrid coordinate ocean model. Various types of observations including in-situ temperature and salinity profiles (mechanical bathythermograph, expendable bathythermograph, Array for Real-time Geostrophic Oceanography, Tropical Atmosphere Ocean Array, conductivity-temperature-depth, station data), remotely-sensed sea surface temperature, and altimetry sea level anomalies, are assimilated into the reanalysis via the ensemble optimal interpolation method. An ensemble of model states sampled from a long-term integration is allowed to change with season, rather than remaining stationary. The estimated background error covariance matrix may reasonably reflect the seasonality and anisotropy. We evaluate the performance of AIPOcean during the period 1993-2006 by comparisons with independent observations, and some reanalysis products. We show that AIPOcean reduces the errors of subsurface temperature and salinity, and reproduces mesoscale eddies. In contrast to ECCO and SODA products, AIPOcean captures the interannual variability and linear trend of sea level anomalies very well. AIPOcean also shows a good consistency with tide gauges.
Keywords: air-sea interaction, background error covariance, china, climate system, doppler, eddy, ensemble optimal interpolation, indonesian throughflow, model, ocean data assimilation, part ii, prediction, radar, reanalysis
ECCO Products Used: ECCO-KFS
URL:
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Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta (2015). Earth rotation and geodynamics, Geodesy and Cartography, 2 (64), 201-242, 10.1515/geocart-2015-0013.
Title: Earth rotation and geodynamics
Type: Journal Article
Publication: Geodesy and Cartography
Author(s): Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta
Year: 2015
Formatted Citation: Bogusz, J., A. Brzezinski, W. Kosek, and J. Nastula, 2015: Earth rotation and geodynamics. Geodesy and Cartography, 64(2), 201-242, doi:10.1515/geocart-2015-0013
Abstract: This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth' magnetic field.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Balmaseda, M A; Hernandez, F; Storto, A; Palmer, M D; Alves, O; Shi, L; Smith, G C; Toyoda, T; Valdivieso, M; Barnier, B; Behringer, D; Boyer, T; Chang, Y S; Chepurin, G A; Ferry, N; Forget, G; Fujii, Y; Good, S; Guinehut, S; Haines, K; Ishikawa, Y; Keeley, S; Köhl, A; Lee, T; Martin, M J; Masina, S; Masuda, S; Meyssignac, B; Mogensen, K; Parent, L; Peterson, K A; Tang, Y M; Yin, Y; Vernieres, G; Wang, X; Waters, J; Wedd, R; Wang, O; Xue, Y; Chevallier, M; Lemieux, J F; Dupont, F; Kuragano, T; Kamachi, M; Awaji, T; Caltabiano, A; Wilmer-Becker, K; Gaillard, F (2015). The Ocean Reanalyses Intercomparison Project (ORA-IP), Journal of Operational Oceanography, sup1 (8), s80-s97, 10.1080/1755876X.2015.1022329.
Title: The Ocean Reanalyses Intercomparison Project (ORA-IP)
Type: Journal Article
Publication: Journal of Operational Oceanography
Author(s): Balmaseda, M A; Hernandez, F; Storto, A; Palmer, M D; Alves, O; Shi, L; Smith, G C; Toyoda, T; Valdivieso, M; Barnier, B; Behringer, D; Boyer, T; Chang, Y S; Chepurin, G A; Ferry, N; Forget, G; Fujii, Y; Good, S; Guinehut, S; Haines, K; Ishikawa, Y; Keeley, S; Köhl, A; Lee, T; Martin, M J; Masina, S; Masuda, S; Meyssignac, B; Mogensen, K; Parent, L; Peterson, K A; Tang, Y M; Yin, Y; Vernieres, G; Wang, X; Waters, J; Wedd, R; Wang, O; Xue, Y; Chevallier, M; Lemieux, J F; Dupont, F; Kuragano, T; Kamachi, M; Awaji, T; Caltabiano, A; Wilmer-Becker, K; Gaillard, F
Year: 2015
Formatted Citation: Balmaseda, M. A. and Coauthors, 2015: The Ocean Reanalyses Intercomparison Project (ORA-IP). Journal of Operational Oceanography, 8(sup1), s80-s97, doi:10.1080/1755876X.2015.1022329
Abstract: Uncertainty in ocean analysis methods and deficiencies in the observing system are major obstacles for the reliable reconstruction of the past ocean climate. The variety of existing ocean reanalyses is exploited in a multi-reanalysis ensemble to improve the ocean state estimation and to gauge uncertainty levels. The ensemble-based analysis of signal-to-noise ratio allows the identification of ocean characteristics for which the estimation is robust (such as tropical mixed-layer-depth, upper ocean heat content), and where large uncertainty exists (deep ocean, Southern Ocean, sea ice thickness, salinity), providing guidance for future enhancement of the observing and data assimilation systems.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V4;GECCO2
Other URLs:
Forget, G; Campin, Jean-Michel; Heimbach, P; Hill, C N; Ponte, R M; Wunsch, C (2015). ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation, Geosci. Model Dev., 10 (8), 3071-3104, 10.5194/gmd-8-3071-2015.
Title: ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation
Type: Journal Article
Publication: Geosci. Model Dev.
Author(s): Forget, G; Campin, Jean-Michel; Heimbach, P; Hill, C N; Ponte, R M; Wunsch, C
Year: 2015
Formatted Citation: Forget, G., J. Campin, P. Heimbach, C. N. Hill, R. M. Ponte, and C. Wunsch, 2015: ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation. Geosci. Model Dev., 8(10), 3071-3104, doi:10.5194/gmd-8-3071-2015
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V2;ECCO-V3;ECCO-V4;ECCO2;GECCO2
Other URLs:
Vondrák, Jan; Ron, C. (2015). Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks, Serbian Astronomical Journal, 191, 59-66, 10.2298/SAJ1591059V.
Title: Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks
Type: Journal Article
Publication: Serbian Astronomical Journal
Author(s): Vondrák, Jan; Ron, C.
Year: 2015
Formatted Citation: Vondrák, J., and C. Ron, 2015: Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks. Serbian Astronomical Journal(191), 59-66, doi:10.2298/SAJ1591059V
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Tyler, Robert (2015). Electromagnetic coupling of ocean flow with the Earth System, Terrestrial, Atmospheric and Oceanic Sciences, 1 (26), 41-52, 10.3319/TAO.2014.08.19.04(GRT).
Title: Electromagnetic coupling of ocean flow with the Earth System
Type: Journal Article
Publication: Terrestrial, Atmospheric and Oceanic Sciences
Author(s): Tyler, Robert
Year: 2015
Formatted Citation: Tyler, R., 2015: Electromagnetic coupling of ocean flow with the Earth System. Terrestrial, Atmospheric and Oceanic Sciences, 26(1), 41-52, doi:10.3319/TAO.2014.08.19.04(GRT)
Abstract:
Keywords: Electrodynamics, Electromagnetic coupling, Induction, Ocean flow
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Halkides, D J; Waliser, Duane E; Lee, Tong; Menemenlis, Dimitris; Guan, Bin (2015). Quantifying the processes controlling intraseasonal mixed-layer temperature variability in the tropical Indian Ocean, Journal of Geophysical Research: Oceans, 2 (120), 692-715, 10.1002/2014JC010139.
Title: Quantifying the processes controlling intraseasonal mixed-layer temperature variability in the tropical Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Halkides, D J; Waliser, Duane E; Lee, Tong; Menemenlis, Dimitris; Guan, Bin
Year: 2015
Formatted Citation: Halkides, D. J., D. E. Waliser, T. Lee, D. Menemenlis, and B. Guan, 2015: Quantifying the processes controlling intraseasonal mixed-layer temperature variability in the tropical Indian Ocean. J. Geophys. Res. Ocean., 120(2), 692-715, doi:10.1002/2014JC010139
Abstract: Spatial and temporal variation of processes that determine ocean mixed-layer (ML) temperature (MLT) variability on the timescale of the Madden-Julian Oscillation (MJO) in the Tropical Indian Ocean (TIO) are examined in a heat-conserving ocean state estimate for years 1993-2011. We introduce a new metric for representing spatial variability of the relative importance of processes. In general, horizontal advection is most important at the Equator. Subsurface processes and surface heat flux are more important away from the Equator, with surface heat flux being the more dominant factor. Analyses at key sites are discussed in the context of local dynamics and literature. At 0°, 80.5°E, for MLT events > 2 standard deviations, ocean dynamics account for more than two thirds of the net tendency during cooling and warming phases. Zonal advection alone accounts for ∼40% of the net tendency. Moderate events (1-2 standard deviations) show more differences between events, and some are dominated by surface heat flux. At 8°S, 67°E in the Seychelles-Chagos Thermocline Ridge (SCTR) area, surface heat flux accounts for ∼70% of the tendency during strong cooling and warming phases; subsurface processes linked to ML depth (MLD) deepening (shoaling) during cooling (warming) account for ∼30%. MLT is more sensitive to subsurface processes in the SCTR, due to the thin MLD, thin barrier layer and raised thermocline. Results for 8°S, 67°E support assertions by Vialard et al. (2008) not previously confirmed due to measurement error that prevented budget closure and the small number of events studied. The roles of MLD, barrier layer thickness, and thermocline depth on different timescales are examined.
Keywords: 4223 Descriptive and regional oceanography, 4231 Equatorial oceanography, 4260 Ocean data assimilation and reanalysis, 4504 Air/sea interactions, 4572 Upper ocean and mixed layer processes, ECCO, Indian Ocean, MJO, intraseasonal, mixed-layer, temperature budget
ECCO Products Used: ECCO-KFS;ECCO2
Other URLs:
Agarwal, Neeraj; Köhl, Armin; Mechoso, Carlos Roberto; Stammer, Detlef (2014). On the Early Response of the Climate System to a Meltwater Input from Greenland, Journal of Climate, 21 (27), 8276-8296, 10.1175/JCLI-D-13-00762.1.
Title: On the Early Response of the Climate System to a Meltwater Input from Greenland
Type: Journal Article
Publication: Journal of Climate
Author(s): Agarwal, Neeraj; Köhl, Armin; Mechoso, Carlos Roberto; Stammer, Detlef
Year: 2014
Formatted Citation: Agarwal, N., A. Köhl, C. R. Mechoso, and D. Stammer, 2014: On the Early Response of the Climate System to a Meltwater Input from Greenland. J. Clim., 27(21), 8276-8296, doi:10.1175/JCLI-D-13-00762.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Tett, S F B; Sherwin, T J; Shravat, A; Browne, O (2014). How Much Has the North Atlantic Ocean Overturning Circulation Changed in the Last 50 Years?, Journal of Climate, 16 (27), 6325-6342, 10.1175/jcli-d-12-00095.1.
Title: How Much Has the North Atlantic Ocean Overturning Circulation Changed in the Last 50 Years?
Type: Journal Article
Publication: Journal of Climate
Author(s): Tett, S F B; Sherwin, T J; Shravat, A; Browne, O
Year: 2014
Formatted Citation: Tett, S. F. B., T. J. Sherwin, A. Shravat, and O. Browne, 2014: How Much Has the North Atlantic Ocean Overturning Circulation Changed in the Last 50 Years? J. Clim., 27(16), 6325-6342, doi:10.1175/jcli-d-12-00095.1
Abstract: Volume transports from six ocean reanalyses are compared with four sets of in situ observations: across the Greenland-Scotland ridge (GSR), in the Labrador Sea boundary current, in the deep western boundary current at 43 degrees N, and in the Atlantic meridional overturning circulation (AMOC) at 26 degrees N in the North Atlantic. The higher-resolution reanalyses (on the order of 1/4 degrees X 1/4 degrees) are better at reproducing the circulation pattern in the subpolar gyre than those with lower resolution (on the order of 1 degrees). Simple Ocean Data Assimilation (SODA) and Estimating the Circulation and Climate of the Ocean (ECCO)-Jet Propulsion Laboratory (JPL) produce transports at 26 degrees N that are close to those observed [17 Sv (1 Sv equivalent to 10(6) m(3) s(-1))]. ECCO, version 2, and SODA produce northward transports across the GSR (observed transport of 8.2 Sv) that are 22% and 29% too big, respectively. By contrast, the low-resolution reanalyses have transports that are either too small [by 31% for ECCO-JPL and 49% for Ocean Reanalysis, system 3 (ORA-S3)] or much too large [Decadal Prediction System (DePreSys)]. SODA had the best simulations of mixed layer depth and with two coarse grid long-term reanalyses (DePreSys and ORA-S3) is used to examine changes in North Atlantic circulation from 1960 to 2008. Its results suggest that the AMOC increased by about 20% at 26 degrees N while transport across the GSR hardly altered. The other (less reliable) long-term reanalyses also had small changes across the GSR but changes of +10% and -20%, respectively, at 26 degrees N. Thus, it appears that changes in the overturning circulation at 26 degrees N are decoupled from the flow across the GSR. It is recommended that transport observations should not be assimilated in ocean reanalyses but used for validation instead.
Keywords: channel, flow, nordic seas, overflow, thermohaline circulation, variability, water
ECCO Products Used: ECCO-KFS;ECCO2
URL:
Other URLs:
Gao, S; Qu, T D; Nie, X W (2014). Mixed layer salinity budget in the tropical Pacific Ocean estimated by a global GCM, Journal of Geophysical Research-Oceans, 12 (119), 8255-8270, 10.1002/2014jc010336.
Title: Mixed layer salinity budget in the tropical Pacific Ocean estimated by a global GCM
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Gao, S; Qu, T D; Nie, X W
Year: 2014
Formatted Citation: Gao, S., T. D. Qu, and X. W. Nie, 2014: Mixed layer salinity budget in the tropical Pacific Ocean estimated by a global GCM. J. Geophys. Res. Ocean., 119(12), 8255-8270, doi:10.1002/2014jc010336
Abstract: The mixed layer salinity (MLS) budget of the tropical Pacific is investigated using results from a model of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). The results focusing on the western Pacific freshwater pool indicate that the long-term averaged surface freshwater flux is well balanced by ocean dynamics, in which the subsurface processes account for the major part. The MLS budget shows significant seasonal and interannual variability, as a consequence of interplay among surface freshwater flux, advection, mixing, and vertical entrainment. On seasonal time scale, both the MLS and mixed layer depth are largely controlled by surface freshwater flux. The opposite phase between the subsurface processes and the barrier layer thickness confirms the important influence of the barrier layer on vertical mixing and entrainment from below. On interannual time scale, all the MLS budget terms show significant ENSO signal, which in turn is highly correlated with the salinity front and barrier layer thickness in the equatorial Pacific.
Keywords: ECCO, ENSO, barrier-layer, circulation model, el-nino, fresh pool, intraseasonal, salinity budget, sea-surface, simulated passive tracer, southern oscillation, temperature, toga decade, tropical Pacific, variability, warm pool, western equatorial pacific
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Webber, B G M; Matthews, A J; Heywood, K J; Kaiser, J; Schmidtko, S (2014). Seaglider observations of equatorial Indian Ocean Rossby waves associated with the Madden-Julian Oscillation, Journal of Geophysical Research-Oceans, 6 (119), 3714-3731, 10.1002/2013jc009657.
Title: Seaglider observations of equatorial Indian Ocean Rossby waves associated with the Madden-Julian Oscillation
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Webber, B G M; Matthews, A J; Heywood, K J; Kaiser, J; Schmidtko, S
Year: 2014
Formatted Citation: Webber, B. G. M., A. J. Matthews, K. J. Heywood, J. Kaiser, and S. Schmidtko, 2014: Seaglider observations of equatorial Indian Ocean Rossby waves associated with the Madden-Julian Oscillation. J. Geophys. Res. Ocean., 119(6), 3714-3731, doi:10.1002/2013jc009657
Abstract: During the CINDY-DYNAMO field campaign of September 2011-January 2012, a Seaglider was deployed at 80 degrees E and completed 10 north-south sections between 3 and 4 degrees S, measuring temperature, salinity, dissolved oxygen concentration, and chlorophyll fluorescence. These high-resolution subsurface observations provide insight into equatorial ocean Rossby wave activity forced by three Madden-Julian Oscillation (MJO) events during this time period. These Rossby waves generate variability in temperature O(1 degrees C), salinity O(0.2 g kg(-1)), density O(0.2 kg m(-3)), and oxygen concentration O(10 mu mol kg(-1)), associated with 10 m vertical displacements of the thermocline. The variability extends down to 1000 m, the greatest depth of the Seaglider observations, highlighting the importance of surface forcing for the deep equatorial ocean. The temperature variability observed by the Seaglider is greater than that simulated in the ECCO-JPL reanalysis, especially at depth. There is also marked variability in chlorophyll fluorescence at the surface and at the depth of the chlorophyll maximum. Upwelling from Rossby waves and local wind stress curl leads to an enhanced shoaling of the chlorophyll maximum by 10-25 m in response to the increased availability of nutrients and light. This influence of the MJO on primary production via equatorial ocean Rossby waves has not previously been recognized.
Keywords: el-nino, kelvin waves, mechanism, pacific, period, tropics, variability, wind
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Vondrák, Jan; Ron, Cyril (2014). Geophysical excitation of nutation - comparasion of different models, Acta Geodynamica et Geomaterialia, 1-8, 10.13168/AGG.2014.0007.
Title: Geophysical excitation of nutation - comparasion of different models
Type: Journal Article
Publication: Acta Geodynamica et Geomaterialia
Author(s): Vondrák, Jan; Ron, Cyril
Year: 2014
Formatted Citation: Vondrák, J., and C. Ron, 2014: Geophysical excitation of nutation - comparasion of different models. Acta Geodynamica et Geomaterialia, 1-8, doi:10.13168/AGG.2014.0007
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Brzeziński, A.; Rajner, M. (2014). Estimation of the Chandler wobble parameters by the use of the Kalman deconvolution filter, Proc Journées 2013 Systèmes de référence spatio-temporels, 189-192.
Title: Estimation of the Chandler wobble parameters by the use of the Kalman deconvolution filter
Type: Conference Proceedings
Publication: Proc Journées 2013 Systèmes de référence spatio-temporels
Author(s): Brzeziński, A.; Rajner, M.
Year: 2014
Formatted Citation: Brzeziński, A., and M. Rajner, 2014: Estimation of the Chandler wobble parameters by the use of the Kalman deconvolution filter. Proc Journées 2013 Systèmes de référence spatio-temporels, N. Capitaine, Eds. Observatoire de Paris, 189-192 pp. https://syrte.obspm.fr/jsr/journees2013/pdf/Brzezinski.pdf.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2;GECCO
Other URLs:
Nastula, Jolanta; Salstein, David A.; Gross, Richard (2014). Regional Multi-Fluid-Based Geophysical Excitation of Polar Motion, Earth on the Edge: Science for a Sustainable Planet, 467-472, 10.1007/978-3-642-37222-3_62.
Title: Regional Multi-Fluid-Based Geophysical Excitation of Polar Motion
Type: Book Section
Publication: Earth on the Edge: Science for a Sustainable Planet
Author(s): Nastula, Jolanta; Salstein, David A.; Gross, Richard
Year: 2014
Formatted Citation: Nastula, J., D. A. Salstein, and R. Gross, 2014: Regional Multi-Fluid-Based Geophysical Excitation of Polar Motion. Earth on the Edge: Science for a Sustainable Planet, C. Rizos, and P. Willis, Eds., Springer-Verlag, 467-472, doi:10.1007/978-3-642-37222-3_62
Abstract: By analyzing geophysical fluids' geographic distribution, we can isolate the regional provenance for some of the important signals in polar motion. An understanding of such will enable us to determine whether certain climate signals can have an impact on polar motion. Here we have compared regional patterns of three surficial fluids: the atmosphere, ocean and land-based hydrosphere. The oceanic excitation function of polar motion was estimated with the ECCO/JPL data-assimilating model, and the atmo- spheric excitation function was determined from NCEP/NCAR reanalyses. The excitation function due to land hydrology was estimated from the Gravity Recovery and Climate Experiment (GRACE) data by an indirect approach that determines water thickness. Our attention focuses on the regional distribution of atmospheric and oceanic excitation of the annual and Chandler wobbles during 1993-2010, and on hydrologic excitation of these wobbles during 2002.9-2011.5. It is found that the regions of maximum fractional covariance (those exceeding a value of 3 10 ) for the annual band are over south Asia, southeast Asia and south central Indian ocean, for hydrology, atmosphere and ocean respectively; and for the Chandler period, areas over North America, Asia, and southern South America; and scattered across the southern oceans for the atmosphere and oceans respectively.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Holme, R.; de Viron, O. (2013). Characterization and implications of intradecadal variations in length of day, Nature, 7457 (499), 202-204, 10.1038/nature12282.
Title: Characterization and implications of intradecadal variations in length of day
Type: Journal Article
Publication: Nature
Author(s): Holme, R.; de Viron, O.
Year: 2013
Formatted Citation: Holme, R., and O. de Viron, 2013: Characterization and implications of intradecadal variations in length of day. Nature, 499(7457), 202-204, doi:10.1038/nature12282
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Jiang, Weiping; Li, Zhao; van Dam, Tonie; Ding, Wenwu (2013). Comparative analysis of different environmental loading methods and their impacts on the GPS height time series, Journal of Geodesy, 7 (87), 687-703, 10.1007/s00190-013-0642-3.
Title: Comparative analysis of different environmental loading methods and their impacts on the GPS height time series
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Jiang, Weiping; Li, Zhao; van Dam, Tonie; Ding, Wenwu
Year: 2013
Formatted Citation: Jiang, W., Z. Li, T. van Dam, and W. Ding, 2013: Comparative analysis of different environmental loading methods and their impacts on the GPS height time series. Journal of Geodesy, 87(7), 687-703, doi:10.1007/s00190-013-0642-3
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Johnson, Gregory C.; Chambers, Don P. (2013). Ocean bottom pressure seasonal cycles and decadal trends from GRACE Release-05: Ocean circulation implications, Journal of Geophysical Research: Oceans, 9 (118), 4228-4240, 10.1002/jgrc.20307.
Title: Ocean bottom pressure seasonal cycles and decadal trends from GRACE Release-05: Ocean circulation implications
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Johnson, Gregory C.; Chambers, Don P.
Year: 2013
Formatted Citation: Johnson, G. C., and D. P. Chambers, 2013: Ocean bottom pressure seasonal cycles and decadal trends from GRACE Release-05: Ocean circulation implications. J. Geophys. Res. Ocean., 118(9), 4228-4240, doi:10.1002/jgrc.20307
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Nie, Xunwei; Gao, Shan; Wang, Fan (2013). Heat budget in the subduction region of the North Pacific central mode water as revealed by a global general circulation model, Marine Sciences, 9 (37), 1-9.
Title: Heat budget in the subduction region of the North Pacific central mode water as revealed by a global general circulation model
Type: Journal Article
Publication: Marine Sciences
Author(s): Nie, Xunwei; Gao, Shan; Wang, Fan
Year: 2013
Formatted Citation: Nie, X., S. Gao, and F. Wang, 2013: Heat budget in the subduction region of the North Pacific central mode water as revealed by a global general circulation model. Marine Sciences, 37(9), 1-9, http://qdhys.ijournal.cn/hykxen/ch/reader/create_pdf.aspx?file_no=20130901&flag=1&year_id=2013&quarter_id=9
Abstract: The mixed layer heat budget in the subduction region of the North Pacific mode water (CMW) was evaluated with 18 years (1993~2010) data obtained using a global general circulation model (GCM). The spatial distribution, seasonal cycle and annual variability of the CMW were investigated. The relationship between the heat budget and the Pacific Decadal Oscillation (PDO) was analyzed emphatically. The results demonstrated that the heat budget in this region was a balance between surface heat forcing and ocean dynamic process. The mixing effect, especially the turbulent diffusion was the dominant component of ocean dynamic process, which played the key role in the dissipation of heat in this region. There was strong seasonal cycle in the temperature and heat budget of this region, which was driven by seasonality in heat flux and mixed layer depth. During the spring and summer, the mixed layer depth (MLD) became very shallow and stable, and the surface forcing was the main factor in control- ling the temporal variability of mixed layer temperature (MLT). Meanwhile the ocean dynamic process was rela- tively weak, of which the mixing was the main component. During the autumn and winter, a dramatic cooling effect on surface leaded to the quick deepening of MLD and subduction, making the vertical entrainment into the principal component of ocean dynamic process. On the contrary, although the mixing effect was still very important, its pro- portion becomes much smaller than that in spring and summer. The lagged correlation between PDO and heat budget in this region indicated that the MLT contained significant PDO signal. The correlation coefficient between the annual variability of heat budget and the temporal tendency of PDO was −0.84. The temporal tendency of PDO was also found to be highly correlated to most components of the heat budget. It was shown from the high correla- tion to the surface forcing that the surface forcing might have important effect on the evolution of PDO. It was suggested from the high correlation to the vertical entrainment that the subducted CMW was very possible to carry the PDO signal. As the main ocean dynamic processes, the mixing and advection seemed to be passively reacted to the variability of PDO.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Dushaw, Brian D.; Worcester, P F; Dzieciuch, M A; Menemenlis, Dimitris (2013). On the time-mean state of ocean models and the properties of long range acoustic propagation, Journal of Geophysical Research: Oceans, 9 (118), 4346-4362, 10.1002/jgrc.20325.
Title: On the time-mean state of ocean models and the properties of long range acoustic propagation
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Dushaw, Brian D.; Worcester, P F; Dzieciuch, M A; Menemenlis, Dimitris
Year: 2013
Formatted Citation: Dushaw, B. D., P. F. Worcester, M. A. Dzieciuch, and D. Menemenlis, 2013: On the time-mean state of ocean models and the properties of long range acoustic propagation. J. Geophys. Res. Ocean., 118(9), 4346-4362, doi:10.1002/jgrc.20325
Abstract: Receptions on three vertical hydrophone arrays from basin-scale acoustic transmissions in the North Pacific during 1996 and 1998 are used to test the time-mean sound-speed properties of the World Ocean Atlas 2005 (WOA05), of an eddying unconstrained simulation of the Parallel Ocean Program (POP), and of three data-constrained solutions provided by the estimating the circulation and climate of the ocean (ECCO) project: a solution based on an approximate Kalman filter from the Jet Propulsion Laboratory (ECCO-JPL), a solution based on the adjoint method from the Massachusetts Institute of Technology (ECCO-MIT), and an eddying solution based on a Green's function approach from ECCO, Phase II (ECCO2). Predictions for arrival patterns using annual average WOA05 fields match observations to within small travel time offsets (0.3-1.0 s). Predictions for arrival patterns from the models differ substantially from the measured arrival patterns, from the WOA05 climatology, and from each other, both in terms of travel time and in the structure of the arrival patterns. The acoustic arrival patterns are sensitive to the vertical gradients of sound speed that govern acoustic propagation. Basin-scale acoustic transmissions, therefore, provide stringent tests of the vertical temperature structure of ocean state estimates. This structure ultimately influences the mixing between the surface waters and the ocean interior. The relatively good agreement of the acoustic data with the more recent ECCO solutions indicates that numerical ocean models have reached a level of accuracy where the acoustic data can provide useful additional constraints for ocean state estimation.
Keywords: 4255 Numerical modeling, 4259 Ocean acoustics, 4260 Ocean data assimilation and reanalysis, 4262 Ocean observing systems, acoustic thermometry, model testing, ocean models
ECCO Products Used: ECCO-KFS;ECCO-V3;ECCO2
Other URLs:
Yan, Youfang; Chassignet, Eric P.; Qi, Yiquan; Dewar, William K. (2013). Freshening of Subsurface Waters in the Northwest Pacific Subtropical Gyre: Observations and Dynamics, Journal of Physical Oceanography, 12 (43), 2733-2751, 10.1175/JPO-D-13-03.1.
Title: Freshening of Subsurface Waters in the Northwest Pacific Subtropical Gyre: Observations and Dynamics
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Yan, Youfang; Chassignet, Eric P.; Qi, Yiquan; Dewar, William K.
Year: 2013
Formatted Citation: Yan, Y., E. P. Chassignet, Y. Qi, and W. K. Dewar, 2013: Freshening of Subsurface Waters in the Northwest Pacific Subtropical Gyre: Observations and Dynamics. Journal of Physical Oceanography, 43(12), 2733-2751, doi:10.1175/JPO-D-13-03.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Landerer, Felix W.; Volkov, Denis L. (2013). The anatomy of recent large sea level fluctuations in the Mediterranean Sea, Geophysical Research Letters, 3 (40), 553-557, 10.1002/grl.50140.
Title: The anatomy of recent large sea level fluctuations in the Mediterranean Sea
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Landerer, Felix W.; Volkov, Denis L.
Year: 2013
Formatted Citation: Landerer, F. W., and D. L. Volkov, 2013: The anatomy of recent large sea level fluctuations in the Mediterranean Sea. Geophys. Res. Lett., 40(3), 553-557, doi:10.1002/grl.50140
Abstract: During the boreal winter months of 2009/2010 and 2010/2011, Mediterranean mean sea level rose 10 cm above the average monthly climatological values. The non-seasonal anomalies were observed in sea surface height (from altimetry), as well as ocean mass (from gravimetry), indicating they were mostly of barotropic nature. These relatively rapid basin-wide fluctuations occurred over time scales of 1-5 months. Here we use observations and re-analysis data to attribute the non-seasonal sea level and ocean mass fluctuations in the Mediterranean Sea to concurrent wind stress anomalies over the adjacent subtropical Northeast Atlantic Ocean, just west of the Strait of Gibraltar, and extending into the strait itself. The observed Mediterranean sea level fluctuations are strongly anti-correlated with the monthly North-Atlantic-Oscillation (NAO) index. Citation: Landerer, F. W., and D. L. Volkov (2013), The anatomy of recent large sea level fluctuations in the Mediterranean Sea, Geophys. Res. Lett., 40, 553-557, doi:10.1002/grl.50140.
Keywords: Mediterranean, ocean mass, sea level
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Schiller, Andreas; Lee, Tong; Masuda, Shuhei (2013). Methods and Applications of Ocean Synthesis in Climate Research, Ocean Circulation and Climate, 581-608, 10.1016/B978-0-12-391851-2.00022-2.
Title: Methods and Applications of Ocean Synthesis in Climate Research
Type: Book Section
Publication: Ocean Circulation and Climate
Author(s): Schiller, Andreas; Lee, Tong; Masuda, Shuhei
Year: 2013
Formatted Citation: Schiller, A., T. Lee, and S. Masuda, 2013: Methods and Applications of Ocean Synthesis in Climate Research. Ocean Circulation and Climate, 581-608, doi:10.1016/B978-0-12-391851-2.00022-2
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2;GECCO
Other URLs:
Jin, Shuanggen (2013). Satellite Gravimetry: Mass Transport and Redistribution in the Earth System, Geodetic Sciences - Observations, Modeling and Applications, 157-174, 10.5772/51698.
Title: Satellite Gravimetry: Mass Transport and Redistribution in the Earth System
Type: Book Section
Publication: Geodetic Sciences - Observations, Modeling and Applications
Author(s): Jin, Shuanggen
Year: 2013
Formatted Citation: Jin, S., 2013: Satellite Gravimetry: Mass Transport and Redistribution in the Earth System. Geodetic Sciences - Observations, Modeling and Applications, InTech, 157-174, doi:10.5772/51698
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Ma, Hsi-Yen; Mechoso, C. Roberto; Xue, Yongkang; Xiao, Heng; Neelin, J. David; Ji, Xuan (2013). On the Connection between Continental-Scale Land Surface Processes and the Tropical Climate in a Coupled Ocean-Atmosphere-Land System, Journal of Climate, 22 (26), 9006-9025, 10.1175/JCLI-D-12-00819.1.
Title: On the Connection between Continental-Scale Land Surface Processes and the Tropical Climate in a Coupled Ocean-Atmosphere-Land System
Type: Journal Article
Publication: Journal of Climate
Author(s): Ma, Hsi-Yen; Mechoso, C. Roberto; Xue, Yongkang; Xiao, Heng; Neelin, J. David; Ji, Xuan
Year: 2013
Formatted Citation: Ma, H., C. R. Mechoso, Y. Xue, H. Xiao, J. D. Neelin, and X. Ji, 2013: On the Connection between Continental-Scale Land Surface Processes and the Tropical Climate in a Coupled Ocean-Atmosphere-Land System. J. Clim., 26(22), 9006-9025, doi:10.1175/JCLI-D-12-00819.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Qu, T D; Gao, S; Fine, R A (2013). Subduction of South Pacific Tropical Water and Its Equatorward Pathways as Shown by a Simulated Passive Tracer, Journal of Physical Oceanography, 8 (43), 1551-1565, 10.1175/jpo-d-12-0180.1.
Title: Subduction of South Pacific Tropical Water and Its Equatorward Pathways as Shown by a Simulated Passive Tracer
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Qu, T D; Gao, S; Fine, R A
Year: 2013
Formatted Citation: Qu, T. D., S. Gao, and R. A. Fine, 2013: Subduction of South Pacific Tropical Water and Its Equatorward Pathways as Shown by a Simulated Passive Tracer. Journal of Physical Oceanography, 43(8), 1551-1565, doi:10.1175/jpo-d-12-0180.1
Abstract: This study investigates the subduction of South Pacific Tropical Water (SPTW) and its equatorward pathways using a simulated passive tracer of the consortium Estimating the Circulation & Climate of the Ocean (ECCO). The results show that approximately 5.8 Sv (1 Sv 10(6) m(3) s(-1)) of the SPTW is formed in the subtropical South Pacific Ocean within the density range between 24.0 and 25.0 kg m(-3), of which about 87% is due to vertical pumping and 13% is due to lateral induction, comparing reasonably well with estimates from climatological data. Once subducted, most SPTW spreads in the subtropical South Pacific. Because of the presence of mixing, some portion of the water is transformed, and its tracer-weighted density steadily increases from an initial value of 24.4 to nearly 25.0 kg m(-3) after 13 years of integration. Approximately 42% of the water makes its way into the equatorial Pacific, either through the western boundary or interior pathway. The two equatorward pathways are essentially of equal importance. A large (similar to 70%) portion of the SPTW entering the equatorial region resurfaces in the central equatorial Pacific. The potential impacts of the resurfacing SPTW on the equatorial thermocline and surface stratification are discussed.
Keywords: Ocean circulation, Ocean dynamics, adjoint, climatology, displacements, formation rates, model, ocean circulation, origin, project, subtropical underwater, warm pool
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Valty, Pierre; De Viron, Olivier; Panet, Isabelle; Van Camp, Michel; Legrand, Julitte (2013). Assessing the precision in loading estimates by geodetic techniques in Southern Europe, Geophysical Journal International, 3 (194), 1441-1454, 10.1093/gji/ggt173.
Title: Assessing the precision in loading estimates by geodetic techniques in Southern Europe
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Valty, Pierre; De Viron, Olivier; Panet, Isabelle; Van Camp, Michel; Legrand, Julitte
Year: 2013
Formatted Citation: Valty, P., O. De Viron, I. Panet, M. Van Camp, and J. Legrand, 2013: Assessing the precision in loading estimates by geodetic techniques in Southern Europe. Geophysical Journal International, 194(3), 1441-1454, doi:10.1093/gji/ggt173
Abstract: This paper investigates the precision of the estimation of geophysical fluid load deformation computed from GRACE space gravity, GPS vertical displacement and geophysical fluids models [Global Circulation Models (GCMs) for ocean, atmosphere and hydrology], using the three-cornered hat method. This method allows the estimation of the variance of the errors of each technique, when the same quantity is monitored by three instruments with independent errors. Applied on a network of stations, several points of view can be considered: the technique level (in order to determine the error of each technique: GRACE, GPS and GCMs), the solution level (allowing to compare the precision of the same technique when different strategies/models are used), and the station level (in order to emphasize local anomalies and geographical patterns). In particular, our results show a precision of the loading vertical displacement at the level of 1 mm when using GRACE or the fluid models, and of 2 mm using GPS. We do not find significant differences between the precision of different solutions of the same techniques, even when there are strong differences in the data processing.
Keywords: Europe, Global change from geodesy, Space geodetic surveys, Time variable gravity, Time-series analysis
ECCO Products Used: ECCO-KFS
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Qu, T D; Gao, S; Fukumori, I (2013). Formation of salinity maximum water and its contribution to the overturning circulation in the North Atlantic as revealed by a global general circulation model, Journal of Geophysical Research-Oceans, 4 (118), 1982-1994, 10.1002/jgrc.20152.
Title: Formation of salinity maximum water and its contribution to the overturning circulation in the North Atlantic as revealed by a global general circulation model
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Qu, T D; Gao, S; Fukumori, I
Year: 2013
Formatted Citation: Qu, T. D., S. Gao, and I. Fukumori, 2013: Formation of salinity maximum water and its contribution to the overturning circulation in the North Atlantic as revealed by a global general circulation model. J. Geophys. Res. Ocean., 118(4), 1982-1994, doi:10.1002/jgrc.20152
Abstract: The formation of salinity maximum water in the North Atlantic is investigated using a simulated passive tracer and its adjoint. The results reveal that most salinity maximum water in the North Atlantic comes from the northwestern part of the subtropical gyre, and direct contribution from the evaporation-precipitation maximum region via the surface Ekman current is minor. Water originating from the evaporation-precipitation maximum region has to recirculate in the subtropical gyre before entering the sea surface salinity maximum region from the northwest. Once subducted, some portion (similar to 10%) of the salinity maximum water enters the equatorial region in the shallow subtropical cell, but most (similar to 70%) of it appears to turn northward to join the North Atlantic Deep Water. The latter pathway involves a three-dimensional circulation. When the warm, fresh surface water flows northward along the western boundary, it turns eastward in the northern subtropical gyre. As a result of the large excess of evaporation over precipitation, this water gradually gains its salinity on the route, until it reaches the sea surface salinity maximum region in the central subtropical gyre. From there, the salinity maximum water is subducted and flows back to the western boundary in the depth range of the thermocline. With its high-salinity nature, a major portion of this water penetrates into the subpolar region and directly contributes to the deep thermohaline circulation.
Keywords: North Atlantic, climatology, deep, formation, ocean, overturning circulation, pacific, pathways, salinity maximum, sea-surface salinity, trends, tropical atlantic, variability, ventilation
ECCO Products Used: ECCO-KFS
URL:
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Makowski, Jessica (2013). Understanding Transport Variability of the Antarctic Circumpolar Current Using Ocean Bottom Pressure.
Title: Understanding Transport Variability of the Antarctic Circumpolar Current Using Ocean Bottom Pressure
Type: Thesis
Publication:
Author(s): Makowski, Jessica
Year: 2013
Formatted Citation: Makowski, J., 2013: Understanding Transport Variability of the Antarctic Circumpolar Current Using Ocean Bottom Pressure.(January), 61 pp. https://scholarcommons.usf.edu/etd/4915.
Abstract: Previous studies have suggested that ocean bottom pressure (OBP) can be used to measure the transport variability of the Antarctic Circumpolar Current (ACC). The OBP observations from the Gravity Recovery and Climate Experiment (GRACE) are used to calculate transport along the choke point between Antarctica and Australia. Statistical analysis will be conducted to determine the uncertainty of the GRACE observations using a simulated data set. There has been some evidence to suggest that Southern Hemisphere winds and the Southern Annular Mode (SAM) or the Antarctic Oscillation (AAO) play a significant role in accelerating/decelerating ACC transport, along with some contribution from buoyancy forcing. We will examine whether average zonal wind stress, wind stress curl, local zonal winds, or the SAM are representative of the low frequency zonal mass transport variability. Preliminary studies suggest that seasonal variation in transport across the Australia-Antarctica choke point is driven by winds along and north of the northern front of the ACC, the Sub Tropical front (STF). It also appears that interannual variations in transport are related to wind variations centered south of the Sub Antarctic Front (SAF). We have observed a strong negative correlation/positive correlation across the STF of the ACC in the Indian Ocean, which suggests wind stress curl may also be responsible for transport variations.
Keywords: Antarctic Circumpolar Current, GRACE, Ocean Bottom Pressure, Ocean Transport, Southern Ocean
ECCO Products Used: ECCO-KFS
Other URLs:
Seo, H; Xie, S P (2013). Impact of ocean warm layer thickness on the intensity of hurricane Katrina in a regional coupled model, Meteorology and Atmospheric Physics, 1-2 (122), 19-32, 10.1007/s00703-013-0275-3.
Title: Impact of ocean warm layer thickness on the intensity of hurricane Katrina in a regional coupled model
Type: Journal Article
Publication: Meteorology and Atmospheric Physics
Author(s): Seo, H; Xie, S P
Year: 2013
Formatted Citation: Seo, H., and S. P. Xie, 2013: Impact of ocean warm layer thickness on the intensity of hurricane Katrina in a regional coupled model. Meteorology and Atmospheric Physics, 122(1-2), 19-32, doi:10.1007/s00703-013-0275-3
Abstract: The effect of pre-storm subsurface thermal structure on the intensity of hurricane Katrina (2005) is examined using a regional coupled model. The Estimating Circulation and Climate of Ocean (ECCO) ocean state estimate is used to initialize the ocean component of the coupled model, and the source of deficiencies in the simulation of Katrina intensity is investigated in relation to the initial depth of 26 A degrees C isotherm (D26). The model underestimates the intensity of Katrina partly due to shallow D26 in ECCO. Sensitivity tests with various ECCO initial fields indicate that the correct relationship between intensity and D26 cannot be derived because D26 variability is underestimated in ECCO. A series of idealized experiments is carried out by modifying initial ECCO D26 to match the observed range. A more reasonable relationship between Katrina's intensity and pre-storm D26 emerges: the intensity is much more sensitive to D26 than to sea surface temperature (SST). Ocean mixed layer process plays a critical role in modulating inner-core SSTs when D26 is deep, reducing mixed layer cooling and lowering the center pressure of the Katrina. Our result lends strong support to the notion that accurate initialization of pre-storm subsurface thermal structure in prediction models is critical for a skillful forecast of intensity of Katrina and likely other intense storms.
Keywords: data assimilation, gulf-of-mexico, heat-content, loop current, north pacific, prediction scheme ships, sea-surface temperature, steady state hurricanes, thermal structure, tropical cyclone intensity
ECCO Products Used: ECCO-KFS
URL:
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Chen, W; Ray, J; Shen, W B; Huang, C L (2013). Polar motion excitations for an Earth model with frequency-dependent responses: 2. Numerical tests of the meteorological excitations, Journal of Geophysical Research-Solid Earth, 9 (118), 4995-5007, 10.1002/jgrb.50313.
Title: Polar motion excitations for an Earth model with frequency-dependent responses: 2. Numerical tests of the meteorological excitations
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Chen, W; Ray, J; Shen, W B; Huang, C L
Year: 2013
Formatted Citation: Chen, W., J. Ray, W. B. Shen, and C. L. Huang, 2013: Polar motion excitations for an Earth model with frequency-dependent responses: 2. Numerical tests of the meteorological excitations. Journal of Geophysical Research-Solid Earth, 118(9), 4995-5007, doi:10.1002/jgrb.50313
Abstract: Polar motion excitation involves mass redistributions and motions of the Earth system relative to the mantle, as well as the frequency-dependent rheologtimescales y of the Earth, where the latter has recently been modeled in the form of frequency-dependent Love numbers and polar motion transfer functions. At seasonal and intraseasonal time scales, polar motions are dominated by angular momentum fluctuations due to mass redistributions and relative motions in the atmosphere, oceans, and continental water, snow, and ice. In this study, we compare the geophysical excitations derived from various global atmospheric, oceanic, and hydrological models (NCEP, ECCO, ERA40, ERAinterim, and ECMWF operational products), and construct two model sets LDC1 and LDC2 by combining the above models with a least difference method. Comparisons between the geodetic excitation (derived from the polar motion series IERS EOP 08 C04) and the geophysical excitations (based on those meteorological models) imply that the atmospheric models are the most reliable while the hydrological ones are the most inaccurate; that the ERAinterim is, in general, the best model set among the original ones, but the combined models LDC1 and LDC2 are much better than ERAinterim; and that applying the frequency-dependent transfer functions to LDC1 and LDC2 improves their agreements with the geodetic excitation. Thus, we conclude that the combined models LDC1 and LDC2 are reliable, and the frequency-dependent Love numbers and polar motion transfer functions are well modeled.
Keywords: atmospheric angular-momentum, equations, frequency-dependent response, geodetic excitation, length, meteorological excitations, oceans, orientation parameters, polar motion, rotation, series, wobble
ECCO Products Used: ECCO-KFS
URL:
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Ma, Hsi-Yen; Xiao, Heng; Mechoso, C. Roberto; Xue, Yongkang (2013). Sensitivity of Global Tropical Climate to Land Surface Processes: Mean State and Interannual Variability, Journal of Climate, 5 (26), 1818-1837, 10.1175/JCLI-D-12-00142.1.
Title: Sensitivity of Global Tropical Climate to Land Surface Processes: Mean State and Interannual Variability
Type: Journal Article
Publication: Journal of Climate
Author(s): Ma, Hsi-Yen; Xiao, Heng; Mechoso, C. Roberto; Xue, Yongkang
Year: 2013
Formatted Citation: Ma, H., H. Xiao, C. R. Mechoso, and Y. Xue, 2013: Sensitivity of Global Tropical Climate to Land Surface Processes: Mean State and Interannual Variability. J. Clim., 26(5), 1818-1837, doi:10.1175/JCLI-D-12-00142.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Gierach, Michelle M.; Vazquez-Cuervo, Jorge; Lee, Tong; Tsontos, Vardis M. (2013). Aquarius and SMOS detect effects of an extreme Mississippi River flooding event in the Gulf of Mexico, Geophysical Research Letters, 19 (40), 5188-5193, 10.1002/grl.50995.
Title: Aquarius and SMOS detect effects of an extreme Mississippi River flooding event in the Gulf of Mexico
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Gierach, Michelle M.; Vazquez-Cuervo, Jorge; Lee, Tong; Tsontos, Vardis M.
Year: 2013
Formatted Citation: Gierach, M. M., J. Vazquez-Cuervo, T. Lee, and V. M. Tsontos, 2013: Aquarius and SMOS detect effects of an extreme Mississippi River flooding event in the Gulf of Mexico. Geophys. Res. Lett., 40(19), 5188-5193, doi:10.1002/grl.50995
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Meyrath, T.; van Dam, T.; Weigelt, M.; Cheng, M. (2013). An assessment of degree-2 Stokes coefficients from Earth rotation data, Geophysical Journal International, 1 (195), 249-259, 10.1093/gji/ggt263.
Title: An assessment of degree-2 Stokes coefficients from Earth rotation data
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Meyrath, T.; van Dam, T.; Weigelt, M.; Cheng, M.
Year: 2013
Formatted Citation: Meyrath, T., T. van Dam, M. Weigelt, and M. Cheng, 2013: An assessment of degree-2 Stokes coefficients from Earth rotation data. Geophysical Journal International, 195(1), 249-259, doi:10.1093/gji/ggt263
Abstract: Variations in the degree-2 Stokes coefficients C20, C21 and S21 can be used to understand long- and short-term climate forcing. Here we derive changes in these coefficients for the period 2003 January-2012 April using Earth rotation data. Earth rotation data contain contributions from motion terms (the effects of winds and currents) and contributions from the effects of mass redistribution. We remove the effects of tides, atmospheric winds and oceanic currents from our data. We compare two different models of atmospheric and oceanic angular momentum for removing the effects of winds and currents: (1) using products from the National Centers for Environmental Prediction and (2) using data from the European Centre for Medium-range Weather Forecasts (ECMWF). We assess the quality of these motion models by comparing the two resulting sets of degree-2 Stokes coefficients to independent degree-2 estimates from satellite laser ranging (SLR), GRACE and a geophysical loading model. We find a good agreement between the coefficients from Earth rotation and the coefficients from other sources. In general, the agreement is better for the coefficients we obtain by removing winds and currents effects using the ECMWF model. In this case, we find higher correlations with the independent models and smaller scatters in differences. This fact holds in particular for {Delta}C20 and {Delta}C21, whereas we cannot observe a significant difference for {Delta}S21. At the annual and semiannual periods, our Earth rotation derived coefficients agree well with the estimates from the other sources, particularly for {Delta}C21 and {Delta}S21. The slight discrepancies we obtain for {Delta}C20 can probably be explained by errors in the atmospheric models and are most likely the result of an over-/underestimation of the annual and semiannual contributions of atmospheric winds to the length-of-day excitation.
Keywords: Earth rotation variations, Geopotential theory, Satellite geodesy, Time variable gravity
ECCO Products Used: ECCO-KFS
Other URLs:
Luo, Hao; Bracco, Annalisa; Yashayaev, Igor; Di Lorenzo, Emanuele (2012). The interannual variability of potential temperature in the central Labrador Sea, Journal of Geophysical Research: Oceans, C10 (117), 10.1029/2012JC007988.
Title: The interannual variability of potential temperature in the central Labrador Sea
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Luo, Hao; Bracco, Annalisa; Yashayaev, Igor; Di Lorenzo, Emanuele
Year: 2012
Formatted Citation: Luo, H., A. Bracco, I. Yashayaev, and E. Di Lorenzo, 2012: The interannual variability of potential temperature in the central Labrador Sea, Journal of Geophysical Research: Oceans, 117(C10), doi: 10.1029/2012JC007988
Abstract: The interannual variability of potential temperature in the central Labrador Sea is studied with a suite of numerical simulations with an eddy-resolving regional ocean model and compared with available observations. The model successfully reproduces the observed variations in potential temperature at depths comprised between 150 and 2000 m over the period 1980-2009, capturing also the warming trend of the last decade and the deep water formation event in 2008. The suite of experiments allows for quantifying the contribution from the physical forcings responsible for the interannual variability of potential temperature in the region. The local atmospheric forcing drives the interannual signal by driving convection, while the incoming current system along the east coast of Greenland is responsible for about half of the warming trend (~0.3-0.4°C) during the last decade through restratification process. The lateral transport of Irminger water in the convective region into the central Labrador Sea is further analyzed integrating a passive tracer. It is found that the overall amount of Irminger water transported in the convective region of the Labrador Sea is directly correlated with the amount of vertical convective mixing. In the last decade, following the decrease in convective activity, the model reveals a substantial decrease in concentration of Irminger Current water below 500 m in the Labrador Sea interior: by 2010 the overall amount is less than half than in the previous 20 years.
Keywords:
ECCO Products Used: ECCO-KFS
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Hayakawa, Hideaki; Shibuya, Kazuo; Aoyama, Yuichi; Nogi, Yoshifumi; Doi, Koichiro (2012). Ocean bottom pressure variability in the Antarctic Divergence Zone off Lützow-Holm Bay, East Antarctica, Deep Sea Research Part I: Oceanographic Research Papers (60), 22-31, 10.1016/j.dsr.2011.09.005.
Title: Ocean bottom pressure variability in the Antarctic Divergence Zone off Lützow-Holm Bay, East Antarctica
Type: Journal Article
Publication: Deep Sea Research Part I: Oceanographic Research Papers
Author(s): Hayakawa, Hideaki; Shibuya, Kazuo; Aoyama, Yuichi; Nogi, Yoshifumi; Doi, Koichiro
Year: 2012
Formatted Citation: Hayakawa, H., K. Shibuya, Y. Aoyama, Y. Nogi, and K. Doi, 2012: Ocean bottom pressure variability in the Antarctic Divergence Zone off Lützow-Holm Bay, East Antarctica. Deep Sea Research Part I: Oceanographic Research Papers, 60, 22-31, doi:10.1016/j.dsr.2011.09.005
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chambers, D. P.; Bonin, J. A. (2012). Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean, Ocean Science, 5 (8), 859-868, 10.5194/os-8-859-2012.
Title: Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean
Type: Journal Article
Publication: Ocean Science
Author(s): Chambers, D. P.; Bonin, J. A.
Year: 2012
Formatted Citation: Chambers, D. P., and J. A. Bonin, 2012: Evaluation of Release-05 GRACE time-variable gravity coefficients over the ocean. Ocean Science, 8(5), 859-868, doi:10.5194/os-8-859-2012
Abstract: The latest release of GRACE (Gravity Recovery and Climate Experiment) gravity field coefficients (Release-05, or RL05) are evaluated for ocean applications. Data have been processed using the current methodology for Release-04 (RL04) coefficients, and have been compared to output from two different ocean models. Results indicate that RL05 data from the three Science Data Centers - the Center for Space Research (CSR), GeoForschungsZentrum (GFZ), and Jet Propulsion Laboratory (JPL) - are more consistent among themselves than the previous RL04 data. Moreover, the variance of residuals with the output of an ocean model is 50-60% lower for RL05 data than for RL04 data. A more optimized destriping algorithm is also tested, which improves the results slightly. By comparing the GRACE maps with two different ocean models, we can better estimate the uncertainty in the RL05 maps. We find the standard error to be about 1 cm (equivalent water thickness) in the low- and mid-latitudes, and between 1.5 and 2 cm in the polar and subpolar oceans, which is comparable to estimated uncertainty for the output from the ocean models.
Keywords:
ECCO Products Used: ECCO-KFS
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Feng, W; Zhong, M; Xu, H Z (2012). Sea level variations in the South China Sea inferred from satellite gravity, altimetry, and oceanographic data, Science China-Earth Sciences, 10 (55), 1696-1701, 10.1007/s11430-012-4394-3.
Title: Sea level variations in the South China Sea inferred from satellite gravity, altimetry, and oceanographic data
Type: Journal Article
Publication: Science China-Earth Sciences
Author(s): Feng, W; Zhong, M; Xu, H Z
Year: 2012
Formatted Citation: Feng, W., M. Zhong, and H. Z. Xu, 2012: Sea level variations in the South China Sea inferred from satellite gravity, altimetry, and oceanographic data. Science China-Earth Sciences, 55(10), 1696-1701, doi:10.1007/s11430-012-4394-3
Abstract: Sea level variations (SLVs) can be divided into two major components: the steric SLV and the mass-induced SLV. These two components of SLV in the South China Sea (SCS) are studied by using satellite altimetry, GRACE (Gravity Recovery and Climate Experiment) satellite gravity, and oceanographic data on annual and inter-annual timescales. On the annual timescale, the geographic distribution of mass-induced SLV's amplitude jointly estimated from altimetry and the ECCO (Estimation of the Circulation and Climate of the Ocean) model agrees very well with that from GRACE. GRACE observes obvious seasonal mass-induced SLV in the SCS with annual amplitude of 2.7 +/- 0.4 cm, which is consistent with the annual amplitude of 2.7 +/- 0.3 cm estimated from the steric-corrected altimetry. On the inter-annual timescales, the mean SLV in the SCS shows a large oscillation, which is mainly caused by the steric effect. The trend of mean SLV inferred from altimetry in the SCS is 5.5 +/- 0.7 mm/yr for the period of 1993-2009, which is significantly higher than the global sea level rise rate of 3.3 +/- 0.4 mm/yr in the same period. There is no obvious trend signal in the mass-induced SLV detected from GRACE that indicates the water exchange between the SCS and its adjacent seas and land is in balance within the study period.
Keywords: ECCO, GRACE, altimetry, annual cycle, circulation, grace, inference, mass, ocean, sea level variation, surface height, the South China Sea, topex/poseidon, trends, variability
ECCO Products Used: ECCO-KFS
URL:
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Göttl, F.; Schmidt, M.; Heinkelmann, R.; Savcenko, R.; Bouman, J. (2012). Combination of gravimetric and altimetric space observations for estimating oceanic polar motion excitations, Journal of Geophysical Research: Oceans, C10 (117), 10.1029/2012JC007915.
Title: Combination of gravimetric and altimetric space observations for estimating oceanic polar motion excitations
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Göttl, F.; Schmidt, M.; Heinkelmann, R.; Savcenko, R.; Bouman, J.
Year: 2012
Formatted Citation: Göttl, F., M. Schmidt, R. Heinkelmann, R. Savcenko, and J. Bouman, 2012: Combination of gravimetric and altimetric space observations for estimating oceanic polar motion excitations. J. Geophys. Res. Ocean., 117(C10), doi:10.1029/2012JC007915
Abstract: Global dynamic processes cause variations in the Earth's rotation, which are monitored by various geometric observation techniques such as Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Very Long Baseline Interferometry (VLBI) with millimeter accuracy. The integral effect on Earth rotation of mass displacements and motion is therefore precisely known, but the separation of contributions from particular geodynamic processes remains a challenge. Here we show that the oceanic mass effect on Earth rotation can be derived from both time variable gravity field solutions from the Gravity Recovery And Climate Experiment (GRACE) and sea level anomalies (SLA) observed from satellite altimeter missions. The GRACE solutions require filtering and the application of an ocean mask, whereas the SLA need to be corrected for the steric effect as polar motion is only affected by mass redistributions. We assess the accuracy of our oceanic polar motion excitations by using GRACE and SLA solutions from different processing centers. In addition, we compare polar motion excitations from GRACE, satellite altimeter data and their combinations with excitations estimated from ocean models. We show that the combination of gravimetric and altimetric solutions reduces systematic errors of the individual solutions. The combined solutions are about 2 times more accurate than ocean model results and about 3 times more accurate than the so-called reduced geodetic excitation functions. We anticipate our analysis to be valuable input for improved modeling of oceanic mass redistributions.
Keywords:
ECCO Products Used: ECCO-KFS
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Soto-Navarro, F Javier; Criado-Aldeanueva, Francisco (2012). Model Thermohaline Trends in the Mediterranean Sea during the Last Years: A Change with Respect to the Last Decades?, The Scientific World Journal (2012), 8, 10.1100/2012/365698.
Title: Model Thermohaline Trends in the Mediterranean Sea during the Last Years: A Change with Respect to the Last Decades?
Type: Journal Article
Publication: The Scientific World Journal
Author(s): Soto-Navarro, F Javier; Criado-Aldeanueva, Francisco
Year: 2012
Formatted Citation: Soto-Navarro, F. J., and F. Criado-Aldeanueva, 2012: Model Thermohaline Trends in the Mediterranean Sea during the Last Years: A Change with Respect to the Last Decades? The Scientific World Journal, 2012, 8, doi:10.1100/2012/365698
Abstract: Temperature and salinity outputs from ECCO (years 93-09) and GLORYS (years 03-09) models have been used to compute the thermohaline and steric sea level trends in the surface (0-150 m), intermediate (150 m-600 m), and deep (600 m-bottom) layers of the Mediterranean Sea. Some changes with respect to the second half of the 20th century have been observed: the cooling of the upper waters of the entire eastern basin since 1950 seems to have vanished; the warming of WMDW historically reported for the second half of the last century could have reversed, although there is no agreement between both models at this point (trends of different sign are predicted); the salinification of WMDW reported for the previous decades is not observed in the south-westernmost area in the period 93-09, and a clear change from positive to negative in the steric sea level trend with respect to the period 93-05 is detected due to the sharp decreasing steric sea level of years 02-06.
Keywords:
ECCO Products Used: ECCO-KFS
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Nastula, J; Gross, R; Salstein, D A (2012). Oceanic excitation of polar motion: Identification of specific oceanic areas important for polar motion excitation, Journal of Geodynamics (62), 16-23, 10.1016/j.jog.2012.01.002.
Title: Oceanic excitation of polar motion: Identification of specific oceanic areas important for polar motion excitation
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Nastula, J; Gross, R; Salstein, D A
Year: 2012
Formatted Citation: Nastula, J., R. Gross, and D. A. Salstein, 2012: Oceanic excitation of polar motion: Identification of specific oceanic areas important for polar motion excitation. Journal of Geodynamics, 62, 16-23, doi:10.1016/j.jog.2012.01.002
Abstract: In this paper regional values of the oceanic excitation function of polar motion are computed from bottom pressure and oceanic current fields from the ECCO/JPL data-assimilating model kf080 for the period 1993-2009. The influence of different geographic regions of the ocean on the excitation of polar motion is determined by calculating correlations and covariances between these regional excitations and either the global non-atmospheric excitation or the global oceanic excitation. The non-atmospheric excitation is estimated by subtracting the atmospheric signal from the excitation computed from geodetic observations of polar motion; the global oceanic excitation function is equivalent to the sum of the oceanic excitation function computed in every grid point. Our attention focuses on the regional distribution of the oceanic polar motion excitation for two time scales: the seasonal spectral band and the band around the Chandler period. We identified the southern Indian Ocean and the South Pacific Ocean as important regions for non-atmospheric polar motion excitation. The maximum of variability over the southern Indian Ocean is especially important in the case of annual oscillation. The Atlantic Ocean makes less significant contribution to the non-atmospheric polar motion excitation than the Pacific and Indian Ocean in both considered spectral ranges. Inland seas like the Mediterranean and the Sea of Japan have high covariance with the global signals. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: Non-atmospheric excitation, Oceanic excitation, atmospheric angular-momentum, chandler-wobble, earth, models, variability
ECCO Products Used: ECCO-KFS
URL:
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Boehm, S.; Nilsson, T.; Schindelegger, M.; Schuh, H. (2012). Atmospheric and oceanic excitation of Earth rotation, Proceedings of the Journées 2011 "Systèmes de référence spatio-temporels" (JSR2011): Earth rotation, reference systems and celestial mechanics: Synergies of geodesy and astronomy, 101-106.
Title: Atmospheric and oceanic excitation of Earth rotation
Type: Conference Proceedings
Publication: Proceedings of the Journées 2011 "Systèmes de référence spatio-temporels" (JSR2011): Earth rotation, reference systems and celestial mechanics: Synergies of geodesy and astronomy
Author(s): Boehm, S.; Nilsson, T.; Schindelegger, M.; Schuh, H.
Year: 2012
Formatted Citation: Boehm, S., T. Nilsson, M. Schindelegger, and H. Schuh, 2012: Atmospheric and oceanic excitation of Earth rotation. Proceedings of the Journées 2011 "Systèmes de référence spatio-temporels" (JSR2011): Earth rotation, reference systems and celestial mechanics: Synergies of geodesy and astronomy, H. Schuh, S. Boehm, T. Nilsson, and N. Capitaine, Eds. Vienna University of Technology, Vienna, Austria, 101-106 pp. http://syrte.obspm.fr/jsr/journees2011/pdf/boehm.pdf.
Abstract: All kinds of mass variations in the Earth's surface fluids accordingly change the tensor of inertia, while moving particles in wind or current flows induce relative angular momentum. Via interaction with the solid Earth, both matter and motion effects cause fluctuations in the direction of the Earth's rotation axis, signified as polar motion, as well as changes in the angular velocity, expressed, e.g. in terms of length of day (LOD). This paper gives an overview of the most important atmospheric and oceanic effects on polar motion and LOD from subdaily to multi-annual time scales and discusses the variable agreement between the observational evidence of excitation effects and their corresponding geophysical models. Special emphasis, including a brief synopsis of recent results, is placed on tidal phenomena and in particular on those caused by short period ocean tides.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Ray, Richard D.; Egbert, Gary D. (2012). Fortnightly Earth rotation, ocean tides and mantle anelasticity, Geophysical Journal International, 1 (189), 400-413, 10.1111/j.1365-246X.2012.05351.x.
Title: Fortnightly Earth rotation, ocean tides and mantle anelasticity
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Ray, Richard D.; Egbert, Gary D.
Year: 2012
Formatted Citation: Ray, R. D., and G. D. Egbert, 2012: Fortnightly Earth rotation, ocean tides and mantle anelasticity. Geophysical Journal International, 189(1), 400-413, doi:10.1111/j.1365-246X.2012.05351.x
Abstract: This study of the fortnightly Mf tide comprises three main topics: (1) a new determination of the fortnightly component of polar motion and length of day (LOD) from a multidecade time-series of observed space-geodetic data; (2) the use of the polar motion determination as one constraint in the development of a hydrodynamic ocean model of the Mf tide and (3) the use of these results to place new constraints on mantle anelasticity at the Mf tidal period. Our model of the Mf ocean tide assimilates more than 14 years of altimeter data from the Topex/Poseidon and Jason-1 satellites. Because the Mf altimetric signal-to-noise ratio is very small, it is critical that altimeter data not be overweighted. The polar motion data, plus tide-gauge data and independent altimeter data, give useful additional information, with only the polar motion putting constraints on tidal current velocities. The resulting ocean-tide model, plus the dominant elastic body tide, leaves a small residual in observed LOD caused by mantle anelasticity. The inferred effective tidal Q of the anelastic body tide is 90 and is in line with a ωα frequency dependence with α in the range 0.2-0.3.
Keywords: Earth rotation variations, Mantle processes, Tides and planetary waves
ECCO Products Used: ECCO-KFS
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Sanchez-Reales, J M; Vigo, M I; Jin, S; Chao, B F (2012). Global Surface Geostrophic Ocean Currents Derived from Satellite Altimetry and GOCE Geoid, Marine Geodesy (35), 175-189, 10.1080/01490419.2012.718696.
Title: Global Surface Geostrophic Ocean Currents Derived from Satellite Altimetry and GOCE Geoid
Type: Journal Article
Publication: Marine Geodesy
Author(s): Sanchez-Reales, J M; Vigo, M I; Jin, S; Chao, B F
Year: 2012
Formatted Citation: Sanchez-Reales, J. M., M. I. Vigo, S. Jin, and B. F. Chao, 2012: Global Surface Geostrophic Ocean Currents Derived from Satellite Altimetry and GOCE Geoid. Marine Geodesy, 35, 175-189, doi:10.1080/01490419.2012.718696
Abstract: The surface geostrophic currents (SGC) can be derived via the principle of geostrophy from the dynamic height of the ocean, or the deviation of the true, variable sea surface height with respect to the Earth's static geoid, both of which can be measured by geodetic means. Here we calculate the Mean Dynamic Topography (MDT) by subtracting the geoid height determined by the GOCE satellite mission from the Mean Sea Surface Topography (MSST) derived from multi-satellite ocean altimetry (T/P, Jason 1/2, ERS-1/2, GEOSAT). Results for SGC are compared with those obtained from a GRACE-based mean geoid, as well as with the mean circulation patterns from measurements done by in situ drifter buoys and from simulations of the ECCO Ocean General Circulation Model. We found GOCE-based geoid solution clearly leads to significant improvements in the spatial resolution of SGC globally except in the Equatorial band where special filtering may be needed, with current velocities and spatial patterns closest to the in situ measurements of currents, compared with the GRACE-based results or ECCO model simulations that give significantly weaker Values with lower spatial resolution.
Keywords: GOCE, circulation, drifters, geostrophic currents, jet, mean dynamic topography, mission, ocean circulation, ocean dynamic topography, recovery, satellite altimetry, tropical pacific, velocity, wind
ECCO Products Used: ECCO-KFS
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Yan, Haoming; Chao, Benjamin F. (2012). Effect of global mass conservation among geophysical fluids on the seasonal length of day variation, Journal of Geophysical Research: Solid Earth, B2 (117), 10.1029/2011JB008788.
Title: Effect of global mass conservation among geophysical fluids on the seasonal length of day variation
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Yan, Haoming; Chao, Benjamin F.
Year: 2012
Formatted Citation: Yan, H., and B. F. Chao, 2012: Effect of global mass conservation among geophysical fluids on the seasonal length of day variation. Journal of Geophysical Research: Solid Earth, 117(B2), doi:10.1029/2011JB008788
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Brzeziński, Aleksander; Dobslaw, Henryk; Dill, Robert; Thomas, Maik (2012). Geophysical Excitation of the Chandler Wobble Revisited.
Title: Geophysical Excitation of the Chandler Wobble Revisited
Type: Book Section
Publication:
Author(s): Brzeziński, Aleksander; Dobslaw, Henryk; Dill, Robert; Thomas, Maik
Year: 2012
Formatted Citation: Brzeziński, A., H. Dobslaw, R. Dill, and M. Thomas, 2012: Geophysical Excitation of the Chandler Wobble Revisited., 499-505, doi:10.1007/978-3-642-20338-1_60
Abstract: The 14-month Chandler wobble is a free motion of the pole excited by geophysical processes. Several recent studies demonstrated that the combination of atmospheric and oceanic excitations contains enough power at the Chandler frequency and is significantly coherent with the observed free wobble. This paper is an extension of earlier studies by Brzezinski and Nastula (Adv Space Res 30:195-200, 2002), Brzezinski et al. (Oceanic excitation of the Chandler wobble using a 50-year time series of ocean angular momentum. In: Adam J, Schwarz K-P (eds) Vistas for geodesy in the new millennium. IAG Symposia, vol 125. Springer, Berlin, pp 434-439, 2002) using the same method of analysis but other available estimates of atmospheric and oceanic excitation of polar motion. We also try to assess the role of land hydrology in the excitation balance by taking into account the hydrological angular momentum estimates. Our results generally confirm earlier conclusions concerning the atmospheric and oceanic excitation. Adding the hydrological excitation is found to increase slightly the Chandler wobble excitation power, while the improvement of coherence depends on the geophysical models under consideration.
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ECCO Products Used: ECCO-KFS
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Fenoglio-Marc, L.; Rietbroek, R.; Grayek, S.; Becker, M.; Kusche, J.; Stanev, E. (2012). Water mass variation in the Mediterranean and Black Seas, Journal of Geodynamics (59-60), 168-182, 10.1016/j.jog.2012.04.001.
Title: Water mass variation in the Mediterranean and Black Seas
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Fenoglio-Marc, L.; Rietbroek, R.; Grayek, S.; Becker, M.; Kusche, J.; Stanev, E.
Year: 2012
Formatted Citation: Fenoglio-Marc, L., R. Rietbroek, S. Grayek, M. Becker, J. Kusche, and E. Stanev, 2012: Water mass variation in the Mediterranean and Black Seas. Journal of Geodynamics, 59-60, 168-182, doi:10.1016/j.jog.2012.04.001
Abstract: The mass-induced sea level variability and the net mass transport between Mediterranean Sea and Black Sea are derived for the interval between August 2002 and July 2008 from satellite-based observations and from model data. We construct in each basin two time series representing the basin mean mass signal in terms of equivalent water height. The first series is obtained from steric-corrected altimetry while the other is deduced from GRACE data corrected for the contamination by continental hydrology. The series show a good agreement in terms of annual and inter-annual signals, which is in line with earlier works, although different model corrections influence the consistency in terms of seasonal signal and trend. In the Mediterranean Sea, we obtain the best agreement using a steric correction from the regional oceanographic model MFSTEP and a continental hydrological leakage correction derived from the global continental hydrological model WaterGAP2. The inter-annual time series show a correlation of 0.85 and a root mean square (RMS) difference of 15. mm. The two estimates have similar accuracy and their annual amplitude and phase agree within 3. mm and 23 days respectively. The GRACE-derived mass-induced sea level variability yields an annual amplitude of 27 ± 5. mm peaking in December and a trend of 5.3 ± 1.9. mm/yr, which deviates within 3. mm/yr from the altimetry-derived estimate. In the Black Sea, the series are less consistent, with lower accuracy of the GRACE-derived estimate, but still show a promising agreement considering the smaller size of the basin. The best agreement is realized choosing the corrections from WaterGAP2 and from the regional oceanographic model NEMO. The inter-annual time series have a correlation and RMS differences of 0.68 and 55. mm, their annual amplitude and phase agree within 4. mm and 6 days respectively. The GRACE-derived seawater mass signal has an annual amplitude of 32 ± 4. mm peaking in April. On inter-annual time scales, the mass-induced sea level variability is stronger than in the Mediterranean Sea, with an increase from 2003 to 2005 followed by a decrease from 2006 to 2008. Based on mass conservation, the mass-induced sea level variations, river runoff and precipitation minus evaporation are combined to derive the strait flows between the basins and with the Atlantic Ocean. At the Gibraltar strait, the net inflow varies annually with an amplitude of 52±10×10-3Sv peaking end of September (1Sv=106m3s-1). The inflow through the Bosphorus strait displays an annual amplitude of 13±3×10-3Sv peaking in the middle of March. Additionally, an increase of the Gibraltar net inflow (3.4±0.8×10-3Sv/yr) is detected. © 2012 Elsevier Ltd.
Keywords: Black Sea, GRACE, Mass change, Mediterranean Sea, Sea level
ECCO Products Used: ECCO-KFS
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Chen, J.L.; Wilson, C.R.; Zhou, Y.H. (2012). Seasonal excitation of polar motion, Journal of Geodynamics (62), 8-15, 10.1016/j.jog.2011.12.002.
Title: Seasonal excitation of polar motion
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Chen, J.L.; Wilson, C.R.; Zhou, Y.H.
Year: 2012
Formatted Citation: Chen, J., C. Wilson, and Y. Zhou, 2012: Seasonal excitation of polar motion. Journal of Geodynamics, 62, 8-15, doi:10.1016/j.jog.2011.12.002
Abstract:
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ECCO Products Used: ECCO-KFS
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van Dam, T; Collilieux, X; Wuite, J; Altamimi, Z; Ray, J (2012). Nontidal ocean loading: amplitudes and potential effects in GPS height time series, Journal of Geodesy, 11 (86), 1043-1057, 10.1007/s00190-012-0564-5.
Title: Nontidal ocean loading: amplitudes and potential effects in GPS height time series
Type: Journal Article
Publication: Journal of Geodesy
Author(s): van Dam, T; Collilieux, X; Wuite, J; Altamimi, Z; Ray, J
Year: 2012
Formatted Citation: van Dam, T., X. Collilieux, J. Wuite, Z. Altamimi, and J. Ray, 2012: Nontidal ocean loading: amplitudes and potential effects in GPS height time series. Journal of Geodesy, 86(11), 1043-1057, doi:10.1007/s00190-012-0564-5
Abstract: Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean's internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a change in the integrated atmospheric mass over the ocean areas. The only previous global analysis investigating the magnitude of OBP surface displacements used older OBP data sets (van Dam et al. in J Geophys Res 129:507-517, 1997). Since then significant improvements in meteorological forcing models used to predict OBP have been made, augmented by observations from satellite altimetry and expendable bathythermograph profiles. Using more recent OBP estimates from the Estimating the Circulation and Climate of the Ocean (ECCO) project, we reassess the amplitude of the predicted effect of OBP on the height coordinate time series from a global distribution of GPS stations. OBP-predicted loading effects display an RMS scatter in the height of between 0.2 and 3.7 mm, larger than previously reported but still much smaller (by a factor of 2) than the scatter observed due to atmospheric pressure loading. Given the improvement in GPS hardware and data analysis techniques, the OBP signal is similar to the precision of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using the MIT reprocessed solution, mi1. When we compare the predicted OBP height time series with mi1, we find that the scatter is reduced over all stations by 0.1 mm on average with reductions as high as 0.7 mm at some stations. More importantly we are able to reduce the scatter on 65 % of the stations investigated. The annual component of the OBP signal is responsible for 80 % of the reduction in scatter on average. We find that stations located close to semi-enclosed bays or seas are affected by OBP loading to a greater extent than other stations.
Keywords: Annual signals, Height coordinate time series, Loading effects, Ocean bottom pressure, deformation, displacements, grace, gravity, model, pressure, region, solid earth, surface, temperature
ECCO Products Used: ECCO-KFS
URL:
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Marcus, S L; Dickey, J O; Fukumori, I; de Viron, O (2012). Detection of the Earth rotation response to a rapid fluctuation of Southern Ocean circulation in November 2009, Geophysical Research Letters (39), 10.1029/2011gl050671.
Title: Detection of the Earth rotation response to a rapid fluctuation of Southern Ocean circulation in November 2009
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Marcus, S L; Dickey, J O; Fukumori, I; de Viron, O
Year: 2012
Formatted Citation: Marcus, S. L., J. O. Dickey, I. Fukumori, and O. de Viron, 2012: Detection of the Earth rotation response to a rapid fluctuation of Southern Ocean circulation in November 2009. Geophys. Res. Lett., 39, doi:10.1029/2011gl050671
Abstract: At seasonal and shorter periods the solid Earth and its overlying geophysical fluids form a closed dynamical system, which (except for tidal forcing) conserves its total angular momentum. While atmospheric effects dominate changes in the Earth's rate of rotation and hence length-of-day (LOD) on these time scales, the addition of oceanic angular momentum (OAM) estimates has been shown to improve closure of the LOD budget in a statistical sense. Here we demonstrate, for the first time, the signature of a specific, sub-monthly ocean current fluctuation on the Earth's rotation rate, coinciding with recently-reported anomalies which developed in southeast Pacific surface temperature and bottom pressure fields during late 2009. Our results show that concurrent variations in the Antarctic Circumpolar Current (ACC), which saw a sharp drop and recovery in zonal transport during a two-week period in November, were strong enough to cause a detectable change in LOD following the removal of atmospheric angular momentum (AAM) computed from the Modern Era Retrospective Analysis for Research and Applications (MERRA) database. The strong OAM variations driving the LOD-AAM changes were diagnosed from ocean state estimates of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) and involved roughly equal contributions from the current and pressure terms, with in situ confirmation for the latter provided by tide-corrected bottom pressure recorder data from the South Drake Passage site of the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements (ACCLAIM) network. Citation: Marcus, S. L., J. O. Dickey, I. Fukumori, and O. de Viron (2012), Detection of the Earth rotation response to a rapid fluctuation of Southern Ocean circulation in November 2009, Geophys. Res. Lett., 39, L04605, doi:10.1029/2011GL050671.
Keywords: length, of-day variations, signals, variability
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Seoane, L.; Biancale, R.; Gambis, D. (2012). Agreement between Earth’s rotation and mass displacement as detected by GRACE, Journal of Geodynamics (62), 49-55, 10.1016/j.jog.2012.02.008.
Title: Agreement between Earth’s rotation and mass displacement as detected by GRACE
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Seoane, L.; Biancale, R.; Gambis, D.
Year: 2012
Formatted Citation: Seoane, L., R. Biancale, and D. Gambis, 2012: Agreement between Earth's rotation and mass displacement as detected by GRACE. Journal of Geodynamics, 62, 49-55, doi:10.1016/j.jog.2012.02.008
Abstract: The progress in GRACE data processing should improve the estimation of low degree spherical harmonics which are expected to agree better with Earth's rotation observations. The polar motion and length-of-day excitations determined from the spherical harmonics of the GRGS latest release (RL02) are explored and compared to the previous release (RL01). The RL02 gives best fit of the observed annual variations than RL01 and geophysical models do. However, the observed residual signal obtained after removing annual and semiannual oscillations is still better explained by the geophysical models even if RL02 estimates are improved at these frequencies scales. Linear trends are also estimated over study period (2003-2008). The linear trends of χ 1 based on GRACE RL01/02 and EOP are similar but they are very different for χ 2. Further studies with longer time series of GRACE and future gravimetric missions could help better interpret the long term variations and the effects of ice sheet mass loss or post glacial rebound. Concerning LOD variations, GRACE/LAGEOS mass displacement information brings better agreement with EOP observations, compared to the pressure term estimated by models, however the RL02 has not shown significant improvement. © 2012 Elsevier Ltd.
Keywords: GRACE, Gravity field, Length-of-day, Polar motion
ECCO Products Used: ECCO-KFS
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Gierach, Michelle M.; Lee, Tong; Turk, Daniela; McPhaden, Michael J. (2012). Biological response to the 1997-98 and 2009-10 El Niño events in the equatorial Pacific Ocean, Geophysical Research Letters, 10 (39), n/a-n/a, 10.1029/2012GL051103.
Title: Biological response to the 1997-98 and 2009-10 El Niño events in the equatorial Pacific Ocean
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Gierach, Michelle M.; Lee, Tong; Turk, Daniela; McPhaden, Michael J.
Year: 2012
Formatted Citation: Gierach, M. M., T. Lee, D. Turk, and M. J. McPhaden, 2012: Biological response to the 1997-98 and 2009-10 El Niño events in the equatorial Pacific Ocean. Geophys. Res. Lett., 39(10), n/a-n/a, doi:10.1029/2012GL051103
Abstract:
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ECCO Products Used: ECCO-KFS
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Kolaczek, B.; Pasnicka, M.; Nastula, J. (2012). Analysis of the geodetic residuals as differences between geodetic and sum of the atmospheric and oceanic excitation of polar motion, Proc. Journées 2011 "Systèmes de référence spatio-temporels", 164-165.
Title: Analysis of the geodetic residuals as differences between geodetic and sum of the atmospheric and oceanic excitation of polar motion
Type: Conference Proceedings
Publication: Proc. Journées 2011 "Systèmes de référence spatio-temporels"
Author(s): Kolaczek, B.; Pasnicka, M.; Nastula, J.
Year: 2012
Formatted Citation: Kolaczek, B., M. Pasnicka, and J. Nastula, 2012: Analysis of the geodetic residuals as differences between geodetic and sum of the atmospheric and oceanic excitation of polar motion. Proc. Journées 2011 "Systèmes de référence spatio-temporels", H. Schuh, S. Böhm, T. Nilsson, and N. Capitaine, Eds. Observatoire de Paris, 164-165 pp.
Abstract: Up to now studies of geophysical excitation of polar motion containing AAM (Atmo- spheric Angular Momentum), OAM (Oceanic Angular Momentum) and HAM (Hydrological Angular Mo- mentum) excitation functions of polar motion have not achieved the total agreement between geophysical and determined geodetic excitation (GAM, Geodetic Angular Momentum) functions of polar motion (Nas- tula and Kolaczek, 2005; Chen and Wilson, 2005; Brzezinski et al., 2009; Nastula et al., 2011, Gross et al., 2003).
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ECCO Products Used: ECCO-KFS
URL:
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Seitz, F.; Kirschner, S.; Neubersch, D. (2012). Determination of the Earth’s pole tide Love number k 2 from observations of polar motion using an adaptive Kalman filter approach, Journal of Geophysical Research: Solid Earth, B9 (117), 10.1029/2012JB009296.
Title: Determination of the Earth’s pole tide Love number k 2 from observations of polar motion using an adaptive Kalman filter approach
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Seitz, F.; Kirschner, S.; Neubersch, D.
Year: 2012
Formatted Citation: Seitz, F., S. Kirschner, and D. Neubersch, 2012: Determination of the Earth's pole tide Love number k 2 from observations of polar motion using an adaptive Kalman filter approach. Journal of Geophysical Research: Solid Earth, 117(B9), doi:10.1029/2012JB009296
Abstract:
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ECCO Products Used: ECCO-KFS
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Chen, J. L.; Wilson, C. R. (2012). Multi-Sensor Monitoring of Low-Degree Gravitational Changes, VII Hotine-Marussi Symposium on Mathematical Geodesy. International Association of Geodesy Symposia (137), 293-300, 10.1007/978-3-642-22078-4.
Title: Multi-Sensor Monitoring of Low-Degree Gravitational Changes
Type: Book Section
Publication: VII Hotine-Marussi Symposium on Mathematical Geodesy. International Association of Geodesy Symposia
Author(s): Chen, J. L.; Wilson, C. R.
Year: 2012
Formatted Citation: Chen, J. L., and C. R. Wilson, 2012: Multi-Sensor Monitoring of Low-Degree Gravitational Changes. VII Hotine-Marussi Symposium on Mathematical Geodesy. International Association of Geodesy Symposia, N. Sneeuw, P. Novák, M. Crespi, and F. Sansó, Eds., Springer-Verlag, 137, 293-300, doi:10.1007/978-3-642-22078-4
Abstract: Earth gravity change is caused by mass redistribution within the Earth system, including air and water redistribution in the atmosphere, ocean, land, and cryosphere, and mass variation of the solid Earth (in the core, mantle, and crust). Gravity change can be quantified by geodetic measurements and numerical climate models. We estimate time series of low-degree gravitational variations, ΔC21, ΔS21, and ΔC20 using four different techniques, from the Gravity Recovery and Climate Experiment (GRACE), Earth Orientation Parameters (length of day and polar motion), advanced climate models (including atmospheric, oceanic, and hydrologic models), and satellite laser ranging. We compare these independent estimates at different time scales, and discuss major uncertainties for the various techniques. Independent estimates of ΔC21, ΔS21, and ΔC20 are important for validating the geodetic techniques and for improving understanding of large scale and low frequency mass redistribution within the Earth system.
Keywords: climate models, earth rotation, grace, low degree gravity, slr
ECCO Products Used: ECCO-KFS
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Yan, Y F; Xu, D Z; Qi, Y Q; Gan, Z J (2012). Observations of Freshening in the Northwest Pacific Subtropical Gyre near Luzon Strait, Atmosphere-Ocean (50), 92-102, 10.1080/07055900.2012.715078.
Title: Observations of Freshening in the Northwest Pacific Subtropical Gyre near Luzon Strait
Type: Journal Article
Publication: Atmosphere-Ocean
Author(s): Yan, Y F; Xu, D Z; Qi, Y Q; Gan, Z J
Year: 2012
Formatted Citation: Yan, Y. F., D. Z. Xu, Y. Q. Qi, and Z. J. Gan, 2012: Observations of Freshening in the Northwest Pacific Subtropical Gyre near Luzon Strait. Atmosphere-Ocean, 50, 92-102, doi:10.1080/07055900.2012.715078
Abstract: Argo observations reveal that the salinity in the North Pacific subtropical gyre near Luzon Strait gradually declined by 0.2 (practical salinity scale used) from 2003 to 2007 over a depth range of 100 m to 200 m. Such freshening is also found in the outputs of the Estimating the Circulation and Climate of the Ocean (ECCO) model. The possible mechanisms for the freshening are investigated using the surface freshwater flux (E-P) data, the ECCO outputs and a salt budget equation for the upper ocean. Our analysis indicates that the magnitude of the salinity change caused by the surface freshwater flux anomaly is far smaller than observed, suggesting that the surface freshwater flux anomaly is not sufficient to account for the observed freshening. In fact, the salinity anomaly is closely linked to a pronounced freshening at the northeast corner of the study area from 2003 to 2007. The advection of salinity anomalies in the western North Pacific Ocean between 25 degrees N and 35 degrees N via a southwestward flow in the "C-shaped" region associated with the Kuroshio system is the main mechanism responsible for the observed freshening in the study area.
Keywords: Argo, Northwest Pacific, barrier layer, el-nino, freshening, interannual variations, mixed-layer, ocean, precipitation, sea-surface salinity, temperature, tropical pacific, upper ocean, western equatorial pacific
ECCO Products Used: ECCO-KFS
URL:
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Inazu, Daisuke; Hino, Ryota (2011). Temperature correction and usefulness of ocean bottom pressure data from cabled seafloor observatories around Japan for analyses of tsunamis, ocean tides, and low-frequency geophysical phenomena, Earth, Planets and Space, 11 (63), 1133-1149, 10.5047/eps.2011.07.014.
Title: Temperature correction and usefulness of ocean bottom pressure data from cabled seafloor observatories around Japan for analyses of tsunamis, ocean tides, and low-frequency geophysical phenomena
Type: Journal Article
Publication: Earth, Planets and Space
Author(s): Inazu, Daisuke; Hino, Ryota
Year: 2011
Formatted Citation: Inazu, D. and R. Hino, 2011: Temperature correction and usefulness of ocean bottom pressure data from cabled seafloor observatories around Japan for analyses of tsunamis, ocean tides, and low-frequency geophysical phenomena, Earth, Planets and Space, 63(11), 1133-1149, doi: 10.5047/eps.2011.07.014
Abstract: Ocean bottom pressure (OBP) data obtained by cabled seafloor observatories deployed around Japan, are known to be significantly affected by temperature changes. This paper examines the relationship between the OBP and temperature records of six OBP gauges in terms of a regression coefficient and lag at a wide range of frequencies. No significant temperature dependency is recognized in secular variations, while substantial increases, at rates of the order of 1 hPa/year, are commonly evident in the OBP records. Strong temperature dependencies are apparent for periods of hours to days, and we correct the OBP data based on the estimated OBP-temperature relationship. At periods longer than days, the temperature corrections work well for extracting geophysical signals for OBP data at a station off Hokkaido (KPG2), while other corrected data show insufficient signal-to-noise ratios. At a tsunami frequency, the correction can reduce OBP fluctuations, due to rapid temperature changes, by as much as millimeters, and is especially effective for data at a station off Shikoku (MPG2) at which rapid temperature changes most frequently occur. A tidal analysis shows that OBP data at a station off Honshu (TM1), and at KPG2, are useful for studies on the long-term variations of tidal constituents.
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ECCO Products Used: ECCO-KFS
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Brown, Jaclyn N.; Fedorov, Alexey V.; Guilyardi, Eric (2011). How well do coupled models replicate ocean energetics relevant to ENSO?, Climate Dynamics, 11-12 (36), 2147-2158, 10.1007/s00382-010-0926-8.
Title: How well do coupled models replicate ocean energetics relevant to ENSO?
Type: Journal Article
Publication: Climate Dynamics
Author(s): Brown, Jaclyn N.; Fedorov, Alexey V.; Guilyardi, Eric
Year: 2011
Formatted Citation: Brown, J.N., A.V. Fedorov, and E. Guilyardi, 2011: How well do coupled models replicate ocean energetics relevant to ENSO?, Climate Dynamics, 36(11-12), 2147-2158, doi: 10.1007/s00382-010-0926-8
Abstract: Accurate replication of the processes associated with the energetics of the tropical ocean is necessary if coupled GCMs are to simulate the physics of ENSO correctly, including the transfer of energy from the winds to the ocean thermocline and energy dissipation during the ENSO cycle. Here, we analyze ocean energetics in coupled GCMs in terms of two integral parameters describing net energy loss in the system using the approach recently proposed by Brown and Fedorov (J Clim 23:1563-1580, 2010a) and Fedorov (J Clim 20:1108-1117, 2007). These parameters are (1) the efficiency γ of the conversion of wind power into the buoyancy power that controls the rate of change of the available potential energy (APE) in the ocean and (2) the e-folding rate α that characterizes the damping of APE by turbulent diffusion and other processes. Estimating these two parameters for coupled models reveals potential deficiencies (and large differences) in how state-of-the-art coupled GCMs reproduce the ocean energetics as compared to ocean-only models and data assimilating models. The majority of the coupled models we analyzed show a lower efficiency (values of γ in the range of 10-50% versus 50-60% for ocean-only simulations or reanalysis) and a relatively strong energy damping (values of α-1 in the range 0.4-1 years versus 0.9-1.2 years). These differences in the model energetics appear to reflect differences in the simulated thermal structure of the tropical ocean, the structure of ocean equatorial currents, and deficiencies in the way coupled models simulate ENSO.
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ECCO Products Used: ECCO-KFS
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Ron, C.; Vondrák, Jan; Štefka, V. (2011). Comparison of the various atmospheric and oceanic angular momentum series, Proc. Journées 2010 Systèmes de référence spatiotemporels, 221-222, 10.1029/2006JC004035.Gross.
Title: Comparison of the various atmospheric and oceanic angular momentum series
Type: Conference Proceedings
Publication: Proc. Journées 2010 Systèmes de référence spatiotemporels
Author(s): Ron, C.; Vondrák, Jan; Štefka, V.
Year: 2011
Formatted Citation: Ron, C., J. Vondrák, and V. Štefka, 2011: Comparison of the various atmospheric and oceanic angular momentum series. Proc. Journées 2010 Systèmes de référence spatiotemporels, N. Capitaine, Eds. Observatoire de Paris, 221-222 pp. doi:10.1029/2006JC004035.Gross.
Abstract:
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ECCO Products Used: ECCO-KFS
URL:
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Halkides, D; Lee, T; Kida, S (2011). Mechanisms controlling the seasonal mixed-layer temperature and salinity of the Indonesian seas, Ocean Dynamics, 4 (61), 481-495, 10.1007/s10236-010-0374-3.
Title: Mechanisms controlling the seasonal mixed-layer temperature and salinity of the Indonesian seas
Type: Journal Article
Publication: Ocean Dynamics
Author(s): Halkides, D; Lee, T; Kida, S
Year: 2011
Formatted Citation: Halkides, D., T. Lee, and S. Kida, 2011: Mechanisms controlling the seasonal mixed-layer temperature and salinity of the Indonesian seas. Ocean Dynamics, 61(4), 481-495, doi:10.1007/s10236-010-0374-3
Abstract: We examine the seasonal mixed-layer temperature (MLT) and salinity (MLS) budgets in the Banda-Arafura Seas region (120-138A degrees E, 8-3A degrees S) using an ECCO ocean-state estimation product. MLT in these seas is relatively high during November-May (austral spring through fall) and relatively low during June-September (austral winter and the period associated with the Asian summer monsoon). Surface heat flux makes the largest contribution to the seasonal MLT tendency, with significant reinforcement by subsurface processes, especially turbulent vertical mixing. Temperature declines (the MLT tendency is negative) in May-August when seasonal insolation is smallest and local winds are strong due to the southeast monsoon, which causes surface heat loss and cooling by vertical processes. In particular, Ekman suction induced by local wind stress curl raises the thermocline in the Arafura Sea, bringing cooler subsurface water closer to the base of the mixed layer where it is subsequently incorporated into the mixed layer through turbulent vertical mixing; this has a cooling effect. The MLT budget also has a small, but non-negligible, semi-annual component since insolation increases and winds weaken during the spring and fall monsoon transitions near the equator. This causes warming via solar heating, reduced surface heat loss, and weakened turbulent mixing compared to austral winter and, to a lesser extent, compared to austral summer. Seasonal MLS is dominated by ocean processes rather than by local freshwater flux. The contributions by horizontal advection and subsurface processes have comparable magnitudes. The results suggest that ocean dynamics play a significant part in determining both seasonal MLT and MLS in the region, such that coupled model studies of the region should use a full ocean model rather than a slab ocean mixed-layer model.
Keywords: ECCO, Indonesian seas, Mixed layer, Ocean-state estimation, Seasonal heat budget, Seasonal salinity, budget, circulation model, gcm, maritime continent, pacific, parameterization, region, sensitivity, throughflow, upper ocean, variability
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Qu, T D; Gao, S; Fukumori, I (2011). What governs the North Atlantic salinity maximum in a global GCM?, Geophysical Research Letters (38), 10.1029/2011gl046757.
Title: What governs the North Atlantic salinity maximum in a global GCM?
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Qu, T D; Gao, S; Fukumori, I
Year: 2011
Formatted Citation: Qu, T. D., S. Gao, and I. Fukumori, 2011: What governs the North Atlantic salinity maximum in a global GCM? Geophys. Res. Lett., 38, doi:10.1029/2011gl046757
Abstract: Taking advantage of the rapid advance in ocean modeling, this study investigates the sea surface salinity maximum in the North Atlantic, using results from a model of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). Salinity budget terms were computed at the model's integration time step and archived as monthly averages. The simulated mixed layer salinity budget provides the first quantitative evidence for the ocean's role in governing the sea surface salinity maximum in the North Atlantic. Our analysis reveals that ocean dynamics explains about half of the sea surface salinity variance, being of equal importance as surface forcing. The sea surface salinity maximum varies both seasonally and interannually, as a consequence of interplay among surface flux, advection, and vertical entrainment. Contribution from eddies and small-scale processes is relatively weak but not negligible. These results may provide useful hints for the design and interpretation of future observations in the region. Citation: Qu, T., S. Gao, and I. Fukumori (2011), What governs the North Atlantic salinity maximum in a global GCM?, Geophys. Res. Lett., 38, L07602, doi:10.1029/2011GL046757.
Keywords: climatology, mixed-layer, model, ocean, sea-surface salinity, trends, tropical atlantic, variability
ECCO Products Used: ECCO-KFS
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Gennerich, Hans-Hermann; Villinger, Heinrich (2011). Deciphering the ocean bottom pressure variation in the Logatchev hydrothermal field at the eastern flank of the Mid-Atlantic Ridge, Geochemistry, Geophysics, Geosystems, 7 (12), 10.1029/2010GC003441.
Title: Deciphering the ocean bottom pressure variation in the Logatchev hydrothermal field at the eastern flank of the Mid-Atlantic Ridge
Type: Journal Article
Publication: Geochemistry, Geophysics, Geosystems
Author(s): Gennerich, Hans-Hermann; Villinger, Heinrich
Year: 2011
Formatted Citation: Gennerich, H., and H. Villinger, 2011: Deciphering the ocean bottom pressure variation in the Logatchev hydrothermal field at the eastern flank of the Mid-Atlantic Ridge. Geochemistry, Geophysics, Geosystems, 12(7), doi:10.1029/2010GC003441
Abstract: Ocean bottom pressure data from the Logatchev hydrothermal field (LHF) are presented and analyzed. The data were collected with two ocean bottom pressure meters (OBPs), constructed at the University of Bremen, that are capable of recording signals with frequencies up to 0.25 Hz. Over the long-term, a nearly 2.5 kPa (25 cm water column equivalent) pressure variation over 3.7 years is observed, which is consistent with uplift followed by subsidence, but cannot unequivocally be discerned from instrumental drift. Medium-term pressure variations are compared with satellite surface topography, satellite gravity, ocean modeling, and in situ data from an OBP 700 km away. It is shown that fluctuations in the oceanic mass distribution dominate the variations in this frequency range and that oceanic modeling and data from a 700 km distant OBP are positively correlated with the LHF bottom pressure time series. The short-term variations are dominated by microseisms originating from sea surface waves and pressure waves from earthquakes as can be shown by comparison with weather buoy and teleseismic data.
Keywords: 1209 Tectonic deformation, 3017 Hydrothermal systems, 3075 Submarine tectonics and volcanism, Logatchev hydrothermal field, Mid-Atlantic Ridge, gravity waves, ocean bottom pressure, seafloor deformation, surface waves
ECCO Products Used: ECCO-KFS;ECCO2
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Lan, Kuo Wei; Lee, Ming An; Lu, Hsueh Jung; Shieh, Wei Juan; Lin, Wei Kuan; Kao, Szu Chia (2011). Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean, ICES Journal of Marine Science, 6 (68), 1063-1071, 10.1093/icesjms/fsr045.
Title: Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean
Type: Journal Article
Publication: ICES Journal of Marine Science
Author(s): Lan, Kuo Wei; Lee, Ming An; Lu, Hsueh Jung; Shieh, Wei Juan; Lin, Wei Kuan; Kao, Szu Chia
Year: 2011
Formatted Citation: Lan, K. W., M. A. Lee, H. J. Lu, W. J. Shieh, W. K. Lin, and S. C. Kao, 2011: Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean. ICES Journal of Marine Science, 68(6), 1063-1071, doi:10.1093/icesjms/fsr045
Abstract: Lan, K-W., Lee, M-A., Lu, H-J., Shieh, W-J., Lin, W-K., and Kao, S-C. 2011. Ocean variations associated with fishing conditions for yellowfin tuna (Thunnus albacares) in the equatorial Atlantic Ocean. - ICES Journal of Marine Science, 68: 1063-1071. In this study, the Taiwanese longline (LL) fishery data were divided into two types: regular LL and deep LL. Furthermore, we collected environmental variables, such as sea surface temperature (SST), subsurface temperature, chlorophyll a concentration, net primary productivity, windspeed, and the north tropical Atlantic SST index (NTA) during the period 1998-2007 to investigate the relationship between LL catch data and oceanic environmental factors using principal component analysis (PCA). After the daily LL was separated into two types of LL, the results indicated that the deep LL was the major fishery catching yellowfin tuna (YFT) in the equatorial Atlantic Ocean. In 2003-2005, especially in 2005, the monthly catch by deep LL was double those of other years. The spatial distribution of the nominal catch per unit effort (cpue) by deep LL showed the maximum aggregation of YFT in waters with temperature above 24-25°C. The YFT mainly aggregated in the equatorial Atlantic, extending east in the first and second quarters of the year. In the third quarter of the year, the SST decreased off West Africa and the YFT migrated westwards to 15°W. Results of PCA indicated that higher subsurface water temperatures resulted in a deeper thermocline and caused a higher cpue of YFT, but the influence of NTA on the cpue of YFT seemed to be insignificant.
Keywords: equatorial Atlantic Ocean, principal component analysis, satellite oceanography, yellowfin tuna
ECCO Products Used: ECCO-KFS
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Aretxabaleta, A L; Smith, K W (2011). Analyzing state-dependent model-data comparison in multi-regime systems, Computational Geosciences, 4 (15), 627-636, 10.1007/s10596-011-9229-3.
Title: Analyzing state-dependent model-data comparison in multi-regime systems
Type: Journal Article
Publication: Computational Geosciences
Author(s): Aretxabaleta, A L; Smith, K W
Year: 2011
Formatted Citation: Aretxabaleta, A. L., and K. W. Smith, 2011: Analyzing state-dependent model-data comparison in multi-regime systems. Computational Geosciences, 15(4), 627-636, doi:10.1007/s10596-011-9229-3
Abstract: An approach to analyze regime change in spatial time series datasets is followed and extended to jointly analyze a dynamical model depicting regime shift and observational data informing the same process. We analyze changes in the joint model-data regime and covariability within each regime. The method is applied to two observational datasets of equatorial sea surface temperature (TAO/TRITON array and satellite) and compared with the predicted data by the ECCO-JPL modeling system.
Keywords: Data clustering, ENSO, Gaussian mixture models, Skill assessment, climate, dynamics, ocean, selection, temperature, time-series, variability
ECCO Products Used: ECCO-KFS
URL:
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Ron, Cyril; Vondrák, Jan (2011). Coherence between geophysical excitations and celestial pole offsets, Acta Geodyn. Geomater., 3 (8), 243-247.
Title: Coherence between geophysical excitations and celestial pole offsets
Type: Journal Article
Publication: Acta Geodyn. Geomater.
Author(s): Ron, Cyril; Vondrák, Jan
Year: 2011
Formatted Citation: Ron, C., and J. Vondrák, 2011: Coherence between geophysical excitations and celestial pole offsets. Acta Geodyn. Geomater., 8(3), 243-247
Abstract: Celestial pole offsets are the displacements between the observed position of the Earth's spin axis in space and its position predicted by the adopted models of precession and nutation. At present, the models are IAU2006 and IAU 2000, respectively. The celestial pole offsets are regularly measured by Very Long-Baseline Interferometry (VLBI), the observations being coordinated and published by the International VLBI Service for Geodesy and Astrometry (IVS). These offsets contain a mixture of several effects: the unpredictable free term, Free Core Nutation (FCN) that is due to the presence of the outer fluid core of the Earth, forced motions excited by the motions in the atmosphere and oceans, and also imperfections of the adopted precession-nutation models. The geophysical excitations are also available, as determined by several atmospheric and oceanographic services. The aim of this paper is to compare the time series of these integrated excitations with the observed celestial pole offsets and estimate the level of coherence between them.
Keywords: celestial pole offsets, coherence, geophysical excitations
ECCO Products Used: ECCO-KFS
URL:
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Hernandez, Fabrice (2011). Performance of Ocean Forecasting Systems-Intercomparison Projects, Operational Oceanography in the 21st Century, 633-655, 10.1007/978-94-007-0332-2_23.
Title: Performance of Ocean Forecasting Systems-Intercomparison Projects
Type: Book Section
Publication: Operational Oceanography in the 21st Century
Author(s): Hernandez, Fabrice
Year: 2011
Formatted Citation: Hernandez, F., 2011: Performance of Ocean Forecasting Systems-Intercomparison Projects. Operational Oceanography in the 21st Century, A. Schiller, Eds., Springer Netherlands, 633-655, doi:10.1007/978-94-007-0332-2_23
Abstract: Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and protein−protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-α-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD ≤ 2.0 Å for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V1;ECCO-V2;GECCO
Other URLs: http://link.springer.com/10.1007/978-94-007-0332-2_23
Karatekin, Ö.; de Viron, O.; Lambert, S.; Dehant, V.; Rosenblatt, P.; Van Hoolst, T.; Le Maistre, S. (2011). Atmospheric angular momentum variations of Earth, Mars and Venus at seasonal time scales, Planetary and Space Science, 10 (59), 923-933, 10.1016/j.pss.2010.09.010.
Title: Atmospheric angular momentum variations of Earth, Mars and Venus at seasonal time scales
Type: Journal Article
Publication: Planetary and Space Science
Author(s): Karatekin, Ö.; de Viron, O.; Lambert, S.; Dehant, V.; Rosenblatt, P.; Van Hoolst, T.; Le Maistre, S.
Year: 2011
Formatted Citation: Karatekin, Ö., O. de Viron, S. Lambert, V. Dehant, P. Rosenblatt, T. Van Hoolst, and S. Le Maistre, 2011: Atmospheric angular momentum variations of Earth, Mars and Venus at seasonal time scales. Planetary and Space Science, 59(10), 923-933, doi:10.1016/j.pss.2010.09.010
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Dwivedi, S.; Haine, T. W.N.; Del Castillo, C. E. (2011). Upper ocean state estimation in the Southern Ocean Gas Exchange Experiment region using the four-dimensional variational technique, Journal of Geophysical Research: Oceans, 3 (116), 1-18, 10.1029/2009JC005615.
Title: Upper ocean state estimation in the Southern Ocean Gas Exchange Experiment region using the four-dimensional variational technique
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Dwivedi, S.; Haine, T. W.N.; Del Castillo, C. E.
Year: 2011
Formatted Citation: Dwivedi, S., T. W. Haine, and C. E. Del Castillo, 2011: Upper ocean state estimation in the Southern Ocean Gas Exchange Experiment region using the four-dimensional variational technique. J. Geophys. Res. Ocean., 116(3), 1-18, doi:10.1029/2009JC005615
Abstract:
Keywords: Southern Ocean, doi:10.1029/2009JC005615, http://dx.doi.org/10.1029/2009JC005615, ocean data assimilation
ECCO Products Used: ECCO-KFS
URL:
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Nastula, Jolanta; Paśnicka, Małgorzata; Kołaczek, Barbara (2011). Comparison of the geophysical excitations of polar motion from the period: 1980.0-2009.0, Acta Geophysica, 3 (59), 561-577, 10.2478/s11600-011-0008-2.
Title: Comparison of the geophysical excitations of polar motion from the period: 1980.0-2009.0
Type: Journal Article
Publication: Acta Geophysica
Author(s): Nastula, Jolanta; Paśnicka, Małgorzata; Kołaczek, Barbara
Year: 2011
Formatted Citation: Nastula, J., M. Paśnicka, and B. Kołaczek, 2011: Comparison of the geophysical excitations of polar motion from the period: 1980.0-2009.0. Acta Geophysica, 59(3), 561-577, doi:10.2478/s11600-011-0008-2
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Jin, S G; Zhang, L J; Tapley, B D (2011). The understanding of length-of-day variations from satellite gravity and laser ranging measurements, Geophysical Journal International, 2 (184), 651-660, 10.1111/j.1365-246X.2010.04869.x.
Title: The understanding of length-of-day variations from satellite gravity and laser ranging measurements
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Jin, S G; Zhang, L J; Tapley, B D
Year: 2011
Formatted Citation: Jin, S. G., L. J. Zhang, and B. D. Tapley, 2011: The understanding of length-of-day variations from satellite gravity and laser ranging measurements. Geophysical Journal International, 184(2), 651-660, doi:10.1111/j.1365-246X.2010.04869.x
Abstract: P>The change in the rate of the Earth's rotation, length-of-day (LOD), is principally the result of movement and redistribution of mass in the Earth's atmosphere, oceans and hydrosphere. Numerous studies on the LOD excitations have been made from climatological/hydrological assimilation systems and models of the general circulation of the ocean. However, quantitative assessment and understanding of the contributions to the LOD remain unclear due mainly to the lack of direct global observations. In this paper, the total Earth's surface fluids mass excitations to the LOD at seasonal and intraseasonal timescales are investigated from the Jet Propulsion Laboratory Estimating Circulation and Climate of the Ocean (ECCO) model, the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis and the European Center for Medium-Range Weather Forecasts (ECMWF) Re-analysis (ERA)-Interim, GRACE-derived surface fluids mass and the spherical harmonics coefficient C-20 from the satellite laser ranging (SLR) as well as combined GRACE+SLR solutions, respectively. Results show that the GRACE and the combined GRACE and SLR solutions better explain the geodetic residual LOD excitations at annual and semi-annual timescales. For less than 1 yr timescales, GRACE-derived mass is worse to explain the geodetic residuals, whereas SLR agrees better with the geodetic residuals. However, the combined GRACE and SLR results are much improved in explaining the geodetic residual excitations at intraseasonal scales.
Keywords: Earth, Satellite geodesy, Time series analysis, Time variable gravity, atmospheric angular-momentum, earths, field, fluctuations, lageos, model, ocean tides, polar motion, rotation, rotation variations, seasonal-variations, variability
ECCO Products Used: ECCO-KFS
URL:
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Stammer, D.; Agarwal, N.; Herrmann, P.; Köhl, A.; Mechoso, C. R. (2011). Response of a Coupled Ocean-Atmosphere Model to Greenland Ice Melting, Surveys in Geophysics, 4-5 (32), 621-642, 10.1007/s10712-011-9142-2.
Title: Response of a Coupled Ocean-Atmosphere Model to Greenland Ice Melting
Type: Journal Article
Publication: Surveys in Geophysics
Author(s): Stammer, D.; Agarwal, N.; Herrmann, P.; Köhl, A.; Mechoso, C. R.
Year: 2011
Formatted Citation: Stammer, D., N. Agarwal, P. Herrmann, A. Köhl, and C. R. Mechoso, 2011: Response of a Coupled Ocean-Atmosphere Model to Greenland Ice Melting. Surveys in Geophysics, 32(4-5), 621-642, doi:10.1007/s10712-011-9142-2
Abstract: We investigate the transient response of the global coupled ocean-atmosphere system to enhanced freshwater forcing representative of melting of the Greenland ice sheets. A 50-year long simulation by a coupled atmosphere-ocean general circulation model (CGCM) is compared with another of the same length in which Greenland melting is prescribed. To highlight the importance of coupled atmosphere-ocean processes, the CGCM results are compared with those of two other experiments carried out with the oceanic general circulation model (OGCM). In one of these OGCM experiments, the prescribed surface fluxes of heat, momentum and freshwater correspond to the unperturbed simulation by the CGCM; in the other experiment, Greenland melting is added to the freshwater flux. The responses by the CGCM and OGCM to the Greenland melting have similar patterns in the Atlantic, albeit the former having five times larger amplitudes in sea surface height anomalies. The CGCM shows likewise stronger variability in all state variables in all ocean basins because the impact of Greenland melting is quickly communicated to all ocean basins via atmospheric bridges. We conclude that the response of the global climate to Greenland ice melting is highly dependent on coupled atmosphere-ocean processes. These lead to reduced latent heat flux into the atmosphere and an associated increase in net freshwater flux into the ocean, especially in the subpolar North Atlantic. The combined result is a stronger response of the coupled system to Greenland ice sheet melting.
Keywords: Coupled atmosphere-ocean experiments, Greenland ice sheet melting, Sealevel rise
ECCO Products Used: ECCO-KFS
URL:
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Halkides, D. J.; Lucas, Lisanne E.; Waliser, Duane E.; Lee, Tong; Murtugudde, Raghu (2011). Mechanisms controlling mixed-layer temperature variability in the eastern tropical Pacific on the intraseasonal timescale, Geophysical Research Letters, 17 (38), 10.1029/2011GL048545.
Title: Mechanisms controlling mixed-layer temperature variability in the eastern tropical Pacific on the intraseasonal timescale
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Halkides, D. J.; Lucas, Lisanne E.; Waliser, Duane E.; Lee, Tong; Murtugudde, Raghu
Year: 2011
Formatted Citation: Halkides, D. J., L. E. Lucas, D. E. Waliser, T. Lee, and R. Murtugudde, 2011: Mechanisms controlling mixed-layer temperature variability in the eastern tropical Pacific on the intraseasonal timescale. Geophys. Res. Lett., 38(17), doi:10.1029/2011GL048545
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D. (2011). Hydrological excitation of polar motion derived from GRACE gravity field solutions, International Journal of Geophysics (2011), 10.1155/2011/174396.
Title: Hydrological excitation of polar motion derived from GRACE gravity field solutions
Type: Journal Article
Publication: International Journal of Geophysics
Author(s): Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D.
Year: 2011
Formatted Citation: Seoane, L., J. Nastula, C. Bizouard, and D. Gambis, 2011: Hydrological excitation of polar motion derived from GRACE gravity field solutions. International Journal of Geophysics, 2011, doi:10.1155/2011/174396
Abstract: The influence of the continental water storage on the polar motion is not well known. Different models have been developed to evaluate these effects and compared to geodetic observations. However, previous studies have shown large discrepancies mainly attributed to the lack of global measurements of related hydrological parameters. Now, from the observations of the GRACE mission, we can estimate the polar motion excitation due to the global hydrology. Data processing of GRACE data is carried out by several centers of analysis, we focus on the new solution computed by the Groupe de Recherche de Géodésie Spatiale. At annual scales, excitations derived from GRACE data are in better agreement with geodetic observations than models estimates. The main contribution to the hydrological excitation comes from the monsoon climates regions where GRACE and models estimates are in a very good agreement. Still, the effect of the north high latitudes regions, where the principal areas of snow cover are found, cannot be neglected. At these regions, GRACE and models estimated contributions to polar motion excitations show significant discrepancies. Finally, GRACE-based excitations reveal the possible influence of water storage variations in exciting polar motion around the frequency of 3 cycles per year.
Keywords:
ECCO Products Used: ECCO-KFS
URL:
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Williams, S D P; Penna, N T (2011). Non-tidal ocean loading effects on geodetic GPS heights, Geophysical Research Letters (38), 10.1029/2011gl046940.
Title: Non-tidal ocean loading effects on geodetic GPS heights
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Williams, S D P; Penna, N T
Year: 2011
Formatted Citation: Williams, S. D. P., and N. T. Penna, 2011: Non-tidal ocean loading effects on geodetic GPS heights. Geophys. Res. Lett., 38, doi:10.1029/2011gl046940
Abstract: GPS observations used in geophysical studies are not usually corrected for non-tidal ocean loading (NTOL) displacement. Here we investigate NTOL effects on 3-4 year GPS height time series from 17 sites around the southern North Sea, and compute the NTOL displacement according to two ocean models; the global ECCO model and a high resolution regional model, POLSSM, which covers the northwest European continental shelf. To assess the susceptibility of GPS height estimates to NTOL, reprocessed GIPSY PPP daily solutions are corrected for the resulting displacement, together with atmospheric pressure loading (ATML). We find that the displacements due to NTOL are comparable in size to ATML and the combined correction reduces the variance by 12-22 mm2 (20-30% reduction in RMS). We find that POLSSM outperforms ECCO, with around an 11% greater variance reduction, and hence high resolution models are recommended to correct GPS heights for NTOL. Citation: Williams, S. D. P., and N. T. Penna (2011), Non-tidal ocean loading effects on geodetic GPS heights, Geophys. Res. Lett., 38, L09314, doi: 10.1029/2011GL046940.
Keywords: deformation, earth, gravity, mass, model, sea-level, surface, tides
ECCO Products Used: ECCO-KFS
URL:
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Gao, S; Qu, T D; Fukumori, I (2011). Effects of mixing on the subduction of South Pacific waters identified by a simulated passive tracer and its adjoint, Dynamics of Atmospheres and Oceans, 1-2 (51), 45-54, 10.1016/J.Dynatmoce.2010.10.002.
Title: Effects of mixing on the subduction of South Pacific waters identified by a simulated passive tracer and its adjoint
Type: Journal Article
Publication: Dynamics of Atmospheres and Oceans
Author(s): Gao, S; Qu, T D; Fukumori, I
Year: 2011
Formatted Citation: Gao, S., T. D. Qu, and I. Fukumori, 2011: Effects of mixing on the subduction of South Pacific waters identified by a simulated passive tracer and its adjoint. Dynamics of Atmospheres and Oceans, 51(1-2), 45-54, doi:10.1016/J.Dynatmoce.2010.10.002
Abstract: Effects of mixing on water mass subduction are analyzed in the South Pacific Ocean. Model simulations using a passive tracer and its adjoint are employed in conjunction with a particle tracking method to distinguish effects of mixing from those of advection. The results show that mixing processes can contribute to as much as 20% of the overall subduction rate in the South Pacific. Of this mixing contribution, about 30% can be attributed to meso-scale eddies, including their associated bolus transport, while the major part (70%) is due to other diabatic processes. The impact of mixing reaches its maximum near the Sub-Antarctic Front, accounting for nearly 30% of the total subduction rate. Consequently, estimates based on tracing particles or on advection alone may significantly underestimate the subduction rate in the South Pacific Ocean. (C) 2010 Elsevier B.V. All rights reserved.
Keywords: circulation, climatology, gcm, mixed-layer, mixing, mode waters, north-pacific, ocean, origin, pathway, south pacific, subduction, thermocline, tracer
ECCO Products Used: ECCO-KFS;adjoint
URL:
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Wu, X; Collilieux, X; Altamimi, Z; Vermeersen, B L A; Gross, R S; Fukumori, I (2011). Accuracy of the International Terrestrial Reference Frame origin and Earth expansion, Geophysical Research Letters (38), L13304, 10.1029/2011gl047450.
Title: Accuracy of the International Terrestrial Reference Frame origin and Earth expansion
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Wu, X; Collilieux, X; Altamimi, Z; Vermeersen, B L A; Gross, R S; Fukumori, I
Year: 2011
Formatted Citation: Wu, X., X. Collilieux, Z. Altamimi, B. L. A. Vermeersen, R. S. Gross, and I. Fukumori, 2011: Accuracy of the International Terrestrial Reference Frame origin and Earth expansion. Geophys. Res. Lett., 38, L13304, doi:10.1029/2011gl047450
Abstract: The International Terrestrial Reference Frame (ITRF) is a fundamental datum for high-precision orbit tracking, navigation, and global change monitoring. Accurately realizing and maintaining ITRF origin at the mean Earth system center of mass (CM) is critical to surface and spacecraft based geodetic measurements including those of sea level rise and its sources. Although ITRF combines data from satellite laser ranging (SLR), Very Long Baseline Interferometry (VLBI), Global Positioning System (GPS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), its origin is currently realized by the single technique of SLR. Consequently, it is difficult to independently evaluate the origin accuracy. Also, whether the solid Earth is expanding or shrinking has attracted persistent attention. The expansion rate, if any, has not been accurately determined before, due to insufficient data coverage on the Earth's surface and the presence of other geophysical processes. Here, we use multiple precise geodetic data sets and a simultaneous global estimation platform to determine that the ITRF2008 origin is consistent with the mean CM at the level of 0.5 mm yr(-1), and the mean radius of the Earth is not changing to within 1 sigma measurement uncertainty of 0.2 mm yr(-1). Citation: Wu, X., X. Collilieux, Z. Altamimi, B. L. A. Vermeersen, R. S. Gross, and I. Fukumori (2011), Accuracy of the International Terrestrial Reference Frame origin and Earth expansion, Geophys. Res. Lett., 38, L13304, doi: 10.1029/2011GL047450.
Keywords: deformation, glacial isostatic-adjustment, grace, model, surface
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Halkides, Daria; Lee, Tong (2011). Mechanisms controlling seasonal mixed layer temperature and salinity in the Southwestern Tropical Indian Ocean, Dynamics of Atmospheres and Oceans, 3 (51), 77-93, 10.1016/j.dynatmoce.2011.03.002.
Title: Mechanisms controlling seasonal mixed layer temperature and salinity in the Southwestern Tropical Indian Ocean
Type: Journal Article
Publication: Dynamics of Atmospheres and Oceans
Author(s): Halkides, Daria; Lee, Tong
Year: 2011
Formatted Citation: Halkides, D., and T. Lee, 2011: Mechanisms controlling seasonal mixed layer temperature and salinity in the Southwestern Tropical Indian Ocean. Dynamics of Atmospheres and Oceans, 51(3), 77-93, doi:10.1016/j.dynatmoce.2011.03.002
Abstract: We use a heat- and salt-conserving ocean state estimation product to study the seasonal cycles of the mixed layer (ML) temperature (MLT) and salinity (MLS) balances over the southwestern tropical Indian Ocean (SWTIO) thermocline ridge (STR; 50°-75°E, 12°-5°S). For seasonal MLT, surface heat flux and ocean processes are both important. They tend to re-enforce each other during peak cooling (May-June) and warming (November) periods, but not during transition periods. The dominant ocean process is wind-driven vertical mixing. It is modulated by the variable strength of the monsoon winds (which affect the vertical diffusivity), and to a lesser extent by variability of thermocline depth (which influences the vertical stratification across the ML base). For example, thermocline shoaling in April-July alters the vertical stratification near the ML base; thus, when the monsoon winds heighten (June-September) and the vertical diffusivity increases (deepening the ML base), relatively cool subsurface water is near the ML base and easily incorporated into the ML by vertical mixing. However, vertical advection as a direct response to thermocline shoaling has little affect on MLT. This explains why MLT and thermocline depth are not positively correlated here on the seasonal timescale (as they are on the interannual timescale). Meridional advection associated with Ekman transport driven by the monsoon winds plays a secondary role. Seasonal MLS, however, is dominated by meridional advection. Vertical process effects on MLS are small, due to a weak salinity gradient near the ML base throughout the year. © 2011 Elsevier B.V.
Keywords: Indian Ocean, Mixed layer budgets, Thermocline ridge
ECCO Products Used: ECCO-KFS
Other URLs:
Lee, T; Stammer, D; Awaji, T; Balmaseda, M; Behringer, D; Carton, J; Ferry, N; Fischer, A; Fukumori, I; Giese, B; Haines, K; Harrison, E; Heimbach, P; Kamachi, M; Keppenne, C; Köhl, A; Masina, S; Menemenlis, Dimitris; Ponte, R; Remy, E; Rienecker, M; Rosati, A; Schroeter, J; Smith, D; Weaver, A; Wunsch, C; Xue, Y (2010). Ocean state estimation for climate research, Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society (Vol. 2), 10.5270/OceanObs09.cwp.55.
Title: Ocean state estimation for climate research
Type: Conference Proceedings
Publication: Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society (Vol. 2)
Author(s): Lee, T; Stammer, D; Awaji, T; Balmaseda, M; Behringer, D; Carton, J; Ferry, N; Fischer, A; Fukumori, I; Giese, B; Haines, K; Harrison, E; Heimbach, P; Kamachi, M; Keppenne, C; Köhl, A; Masina, S; Menemenlis, Dimitris; Ponte, R; Remy, E; Rienecker, M; Rosati, A; Schroeter, J; Smith, D; Weaver, A; Wunsch, C; Xue, Y
Year: 2010
Formatted Citation: Lee, T. and Coauthors, 2010: Ocean state estimation for climate research. Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society (Vol. 2), J. Hall, D. E. Harrison, and D. Stammer, Eds. ESA Publication WPP-306, Venice, Italy, 21-25 September 2009 doi:10.5270/OceanObs09.cwp.55.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V1;ECCO-V2;ECCO2;GECCO
URL:
Other URLs:
Qu, T D; Gao, S; Fukumori, I; Fine, R A; Lindstrom, E J (2010). The Obduction of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer, Journal of Physical Oceanography, 10 (40), 2282-2297, 10.1175/2010jpo4358.1.
Title: The Obduction of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Qu, T D; Gao, S; Fukumori, I; Fine, R A; Lindstrom, E J
Year: 2010
Formatted Citation: Qu, T. D., S. Gao, I. Fukumori, R. A. Fine, and E. J. Lindstrom, 2010: The Obduction of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer. Journal of Physical Oceanography, 40(10), 2282-2297, doi:10.1175/2010jpo4358.1
Abstract: The obduction of equatorial 13 degrees C Water in the Pacific is investigated using a simulated passive tracer of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). The result shows that the 13 degrees C Water initialized in the region 8 degrees N-8 degrees S, 130 degrees-90 degrees W enters the surface mixed layer in the eastern tropical Pacific, mainly through upwelling near the equator, in the Costa Rica Dome, and along the coast of Peru. Approximately two-thirds of this obduction occurs within 10 years after the 13 degrees C Water being initialized, with the upper portion of the water mass reaching the surface mixed layer in only about a month. The obduction of the 13 degrees C Water helps to maintain a cool sea surface temperature year-round, equivalent to a surface heat flux of about -6.0 W m(-2) averaged over the eastern tropical Pacific (15 degrees S-15 degrees N, 130 degrees W-eastern boundary) for the period of integration (1993-2006). During El Nino years, when the thermocline deepens as a consequence of the easterly wind weakening, the obduction of the 13 degrees C Water is suppressed, and the reduced vertical entrainment generates a warming anomaly of up to 10 W m(-2) in the eastern tropical Pacific and in particular along the coast of Peru, providing explanations for the warming of sea surface temperature that cannot be accounted for by local winds alone. The situation is reversed during La Nina years.
Keywords: annual cycle, circulation, costa-rica dome, dynamics, eastern tropical pacific, indonesian throughflow, ocean, sea-surface temperature, subsurface countercurrents, tsuchiya jet
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Dickey, J O; Marcus, S L; de Viron, O (2010). Closure in the Earth’s angular momentum budget observed from subseasonal periods down to four days: No core effects needed, Geophysical Research Letters (37), 10.1029/2009gl041118.
Title: Closure in the Earth’s angular momentum budget observed from subseasonal periods down to four days: No core effects needed
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Dickey, J O; Marcus, S L; de Viron, O
Year: 2010
Formatted Citation: Dickey, J. O., S. L. Marcus, and O. de Viron, 2010: Closure in the Earth's angular momentum budget observed from subseasonal periods down to four days: No core effects needed. Geophys. Res. Lett., 37, doi:10.1029/2009gl041118
Abstract: Short period variations in the Earth's rotation rate, length-of-day (LOD), are driven mainly by the atmosphere with smaller contributions by the oceans. Previous studies have noted a lag of atmospheric angular momentum (AAM) with LOD that would imply another source. We examine AAM from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP) reanalysis series, along with oceanic angular momentum (OAM) from the ECCO consortium; land hydrological effects made no discernible impact. The NCEP reanalysis together with OAM produces a significant lag with LOD, while the ECMWF reanalysis AAM with OAM shows no phase lag. We find significant coherence with LOD variations down to periods of 4 days; coherence losses at shorter periods likely arise from the inverted barometer assumption and unmodeled dynamical processes. Thus the inclusion of core effects is not needed to balance the axial angular momentum budget on sub-seasonal time scales. Citation: Dickey, J. O., S. L. Marcus, and O. de Viron (2010), Closure in the Earth's angular momentum budget observed from subseasonal periods down to four days: No core effects needed, Geophys. Res. Lett., 37, L03307, doi: 10.1029/2009GL041118.
Keywords: length, ocean, topography, variable rotation
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
García-García, D.; Chao, B. F.; Boy, J. P. (2010). Steric and mass-induced sea level variations in the Mediterranean Sea revisited, Journal of Geophysical Research: Oceans, 12 (115), 1-14, 10.1029/2009JC005928.
Title: Steric and mass-induced sea level variations in the Mediterranean Sea revisited
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): García-García, D.; Chao, B. F.; Boy, J. P.
Year: 2010
Formatted Citation: García-García, D., B. F. Chao, and J. P. Boy, 2010: Steric and mass-induced sea level variations in the Mediterranean Sea revisited. J. Geophys. Res. Ocean., 115(12), 1-14, doi:10.1029/2009JC005928
Abstract: The total sea level variation (SLV) is the combination of steric and mass-induced SLV, whose exact shares are key to understanding the oceanic response to climate system changes. Total SLV can be observed by radar altimetry satellites such as TOPEX/POSEIDON and Jason 1/2. The steric SLV can be computed through temperature and salinity profiles from in situ measurements or from ocean general circulation models (OGCM), which can assimilate the said observations. The mass-induced SLV can be estimated from its time-variable gravity (TVG) signals. We revisit this problem in the Mediterranean Sea estimating the observed, steric, and mass-induced SLV, for the latter we analyze the latest TVG data set from the GRACE (Gravity Recovery and Climate Experiment) satellite mission launched in 2002, which is 3.5 times longer than in previous studies, with the application of a two-stage anisotropic filter to reduce the noise in high-degree and -order spherical harmonic coefficients. We confirm that the intra-annual total SLV are only produced by water mass changes, a fact explained in the literature as a result of the wind field around the Gibraltar Strait. The steric SLV estimated from the residual of "altimetry minus GRACE" agrees in phase with that estimated from OGCMs and in situ measurements, although showing a higher amplitude. The net water fluxes through both the straits of Gibraltar and Sicily have also been estimated accordingly. Copyright 2010 by the American Geophysical Union.
Keywords:
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Dushaw, Brian D.; Au, Whitlow; Beszczynska-Möller, Agnieszka; Brainard, Rusty; Cornuelle, Bruce D; Duda, Tim; Dzieciuch, Matthew; Forbes, Andrew; Freitag, Lee; Gascard, Jean-Claude; Gavrilov, Alexander; Gould, John; Howe, Bruce; Jayne, Steven R; Johannessen, Ola M; Lynch, James F; Martin, David; Menemenlis, Dimitris; Mikhalevsky, Peter; Miller, James H; Moore, Sue E; Munk, Walter H; Nystuen, Jeff; Odom, Robert I; Orcutt, John; Rossby, Tom; Sagen, Hanne; Sandven, Stein; Simmen, Jeff; Skarsoulis, Emmanuel; Southall, Brandon; Stafford, Kate; Stephen, Ralph; Vigness-Raposa, Kathleen J; Vinogradov, Sergei; Wong, Kevin B; Worcester, Peter F; Wunsch, Carl (2010). A global ocean acoustic observing network, Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society (2), 10.5270/OceanObs09.cwp.25.
Title: A global ocean acoustic observing network
Type: Conference Proceedings
Publication: Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society
Author(s): Dushaw, Brian D.; Au, Whitlow; Beszczynska-Möller, Agnieszka; Brainard, Rusty; Cornuelle, Bruce D; Duda, Tim; Dzieciuch, Matthew; Forbes, Andrew; Freitag, Lee; Gascard, Jean-Claude; Gavrilov, Alexander; Gould, John; Howe, Bruce; Jayne, Steven R; Johannessen, Ola M; Lynch, James F; Martin, David; Menemenlis, Dimitris; Mikhalevsky, Peter; Miller, James H; Moore, Sue E; Munk, Walter H; Nystuen, Jeff; Odom, Robert I; Orcutt, John; Rossby, Tom; Sagen, Hanne; Sandven, Stein; Simmen, Jeff; Skarsoulis, Emmanuel; Southall, Brandon; Stafford, Kate; Stephen, Ralph; Vigness-Raposa, Kathleen J; Vinogradov, Sergei; Wong, Kevin B; Worcester, Peter F; Wunsch, Carl
Year: 2010
Formatted Citation: Dushaw, B. D. and Coauthors, 2010: A global ocean acoustic observing network. Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society, J. Hall, D. E. Harrison, and D. Stammer, Eds. ESA Publication WPP-306, Venice, Italy, 21-25 September 2009, 2 doi:10.5270/OceanObs09.cwp.25.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO2
URL:
Other URLs:
Chao, Benjamin F.; Yan, Haoming (2010). Relation between length-of-day variation and angular momentum of geophysical fluids, Journal of Geophysical Research, B10 (115), B10417, 10.1029/2009JB007024.
Title: Relation between length-of-day variation and angular momentum of geophysical fluids
Type: Journal Article
Publication: Journal of Geophysical Research
Author(s): Chao, Benjamin F.; Yan, Haoming
Year: 2010
Formatted Citation: Chao, B. F., and H. Yan, 2010: Relation between length-of-day variation and angular momentum of geophysical fluids. Journal of Geophysical Research, 115(B10), B10417, doi:10.1029/2009JB007024
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Lee, T; Awaji, T; Balmaseda, M; Ferry, N; Fujii, Y; Fukumori, I; Giese, B; Heimbach, P; Kohl, A; Masina, S; Remy, E; Rosati, A; Schodlok, M; Stammer, D; Weaver, A (2010). Consistency and fidelity of Indonesian-throughflow total volume transport estimated by 14 ocean data assimilation products, Dynamics of Atmospheres and Oceans, 2 (50), 201-223, 10.1016/J.Dynatmoce.2009.12.004.
Title: Consistency and fidelity of Indonesian-throughflow total volume transport estimated by 14 ocean data assimilation products
Type: Journal Article
Publication: Dynamics of Atmospheres and Oceans
Author(s): Lee, T; Awaji, T; Balmaseda, M; Ferry, N; Fujii, Y; Fukumori, I; Giese, B; Heimbach, P; Kohl, A; Masina, S; Remy, E; Rosati, A; Schodlok, M; Stammer, D; Weaver, A
Year: 2010
Formatted Citation: Lee, T. and Coauthors, 2010: Consistency and fidelity of Indonesian-throughflow total volume transport estimated by 14 ocean data assimilation products. Dynamics of Atmospheres and Oceans, 50(2), 201-223, doi:10.1016/J.Dynatmoce.2009.12.004
Abstract: Monthly averaged total volume transport of the Indonesian throughflow (ITF) estimated by 14 global ocean data assimilation (ODA) products that are decade to multi-decade long are compared among themselves and with observations from the INSTANT Program (2004-2006). The main goals of the comparisons are to examine the consistency and evaluate the skill of different ODA products in simulating ITF transport. The ensemble averaged, time-mean value of ODA estimates is 13.6 Sv (1 Sv = 10(6) m(3)/s) for the common 1993-2001 period and 13.9 Sv for the 2004-2006 INSTANT Program period. These values are close to the 15-Sv estimate derived from INSTANT observations. All hut one ODA time-mean estimate fall within the range of uncertainty of the INSTANT estimate. In terms of temporal variability, the scatter among different ODA estimates averaged over time is 1.7 Sv, which is substantially smaller than the magnitude of the temporal variability simulated by the ODA systems. Therefore, the overall "signal-to-noise" ratio for the ensemble estimates is larger than one. The best consistency among the products occurs on seasonal-to-interannual time scales, with generally stronger (weaker) ITF during boreal summer (winter) and during La Nina (El Nino) events. The scatter among different products for seasonal-to-interannual time scales is approximately 1 Sv. Despite the good consistency, systematic difference is found between most ODA products and the INSTANT observations. All but the highest-resolution (18 km) ODA product show a dominant annual cycle while the INSTANT estimate and the 18-km product exhibit a strong semi-annual signal. The coarse resolution is an important factor that limits the level of agreement between ODA and INSTANT estimates. Decadal signals with periods of 10-15 years are seen. The most conspicuous and consistent decadal change is a relatively sharp increase in ITF transport during 1993-2000 associated with the strengthening tropical Pacific trade wind. Most products do not show a weakening ITF after the mid-1970s' associated with the weakened Pacific trade wind. The scatter of ODA estimates is smaller after than before 1980, reflecting the impact of the enhanced observations after the 1980s. To assess the representativeness of using the average over a three-year period (e.g., the span of the INSTANT Program) to describe longer-term mean, we investigate the temporal variations of the three-year low-pass ODA estimates. The average variation is about 3.6 Sv, which is largely due to the increase of ITF transport from 1993 to 2000. However, the three-year average during the 2004-2006 INSTANT Program period is within 0.5 Sv of the long-term mean for the past few decades. (C) 2010 Elsevier B.V. All rights reserved.
Keywords: circulation model, climate system, gcm, global ocean, indonesian throughflow, interannual variability, north-atlantic, ocean data assimilation, pacific, temperature
ECCO Products Used: ECCO-KFS;ECCO-V1;ECCO-V3;ECCO2;GECCO
URL:
Other URLs:
Ferrari, Raffaele; Wunsch, Carl (2010). The distribution of eddy kinetic and potential energies in the global ocean, Tellus A, 2 (62), 92-108, 10.1111/j.1600-0870.2009.00432.x.
Title: The distribution of eddy kinetic and potential energies in the global ocean
Type: Journal Article
Publication: Tellus A
Author(s): Ferrari, Raffaele; Wunsch, Carl
Year: 2010
Formatted Citation: Ferrari, R., and C. Wunsch, 2010: The distribution of eddy kinetic and potential energies in the global ocean. Tellus A, 62(2), 92-108, doi:10.1111/j.1600-0870.2009.00432.x
Abstract: Understanding of the major sources, sinks, and reservoirs of energy in the ocean is briefly updated in a diagram. The nature of the dominant kinetic energy reservoir, that of the balanced variablity, is then found to be indistinguishable in the observations from a sum of barotropic and first baroclinic ordinary quasi-geostrophic modes. Little supporting evidence is available to partition the spectra among forced motions and turbulent cascades, along with significant energy more consistent with weakly non-linear wave dynamics. Linear-response wind-forced motions appear to dominate the high frequency (but subinertial) mooring frequency spectra. Turbulent cascades appear to fill the high wavenumber spectra in altimetric data and numerical simulations. Progress on these issues is hindered by the difficulty in connecting the comparatively easily available frequency spectra with the variety of theoretically predicted wavenumber spectra.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V2;ECCO2
Other URLs:
Vondrák, Jan; Ron, Cyril (2010). Study of atmospheric and oceanic excitations in the motion of earth’s spin axis in space, Acta Geodynamica et Geomaterialia, 1 (7), 19-28.
Title: Study of atmospheric and oceanic excitations in the motion of earth’s spin axis in space
Type: Journal Article
Publication: Acta Geodynamica et Geomaterialia
Author(s): Vondrák, Jan; Ron, Cyril
Year: 2010
Formatted Citation: Vondrák, J., and C. Ron, 2010: Study of atmospheric and oceanic excitations in the motion of earth's spin axis in space. Acta Geodynamica et Geomaterialia, 7(1), 19-28
Abstract:
Keywords: Earth orientation, Geophysical excitation, Nutation, VLBI
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Jin, S G; Chambers, D P; Tapley, B D (2010). Hydrological and oceanic effects on polar motion from GRACE and models, Journal of Geophysical Research-Solid Earth (115), 10.1029/2009jb006635.
Title: Hydrological and oceanic effects on polar motion from GRACE and models
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Jin, S G; Chambers, D P; Tapley, B D
Year: 2010
Formatted Citation: Jin, S. G., D. P. Chambers, and B. D. Tapley, 2010: Hydrological and oceanic effects on polar motion from GRACE and models. Journal of Geophysical Research-Solid Earth, 115, doi:10.1029/2009jb006635
Abstract: Terrestrial water storage (TWS) and ocean bottom pressure (OBP) are major contributors to the observed polar motion excitations, second only to atmospheric mass movement. However, quantitative assessment of the hydrological and oceanic effects on polar motion remains unclear because of the lack of global observations. In this paper, hydrological and oceanic mass excitations to polar motion are investigated using monthly TWS and OBP derived from the Gravity Recovery and Climate Experiment (GRACE) for January 2003 until December 2008. The results from this analysis are compared with hydrological model excitations from the European Center for Medium-Range Weather Forecasts (ECMWF) and oceanic model excitations obtained from the Jet Propulsion Laboratory (JPL) using Estimating the Circulation and Climate of the Ocean (ECCO). Results show that the GRACE-derived OBP and TWS better explain the geodetic residual polar motion excitations for the Px component at the annual period, while the GRACE OBP and ECMWF hydrological angular momentum agree better with the geodetic residuals for the annual Py excitation. GRACE ocean and hydrology excitations better explain the geodetic residuals for the semiannual Py excitation. However, the JPL ECCO and ECMWF models better explain the intraseasonal geodetic residual of polar motion excitation in the Px and Py components. The GRACE data demonstrate much higher intraseasonal variability than either the models or the geodetic observations.
Keywords: atmospheric excitation, chandler-wobble, climate, currents, earths variable rotation, gravity, length, seasonal-variations, variability, water
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Dobslaw, H.; Dill, R.; Grötzsch, A.; Brzeziński, Aleksander; Thomas, M. (2010). Seasonal polar motion excitation from numerical models of atmosphere, ocean, and continental hydrosphere, Journal of Geophysical Research, B10 (115), B10406, 10.1029/2009JB007127.
Title: Seasonal polar motion excitation from numerical models of atmosphere, ocean, and continental hydrosphere
Type: Journal Article
Publication: Journal of Geophysical Research
Author(s): Dobslaw, H.; Dill, R.; Grötzsch, A.; Brzeziński, Aleksander; Thomas, M.
Year: 2010
Formatted Citation: Dobslaw, H., R. Dill, A. Grötzsch, A. Brzeziński, and M. Thomas, 2010: Seasonal polar motion excitation from numerical models of atmosphere, ocean, and continental hydrosphere. Journal of Geophysical Research, 115(B10), B10406, doi:10.1029/2009JB007127
Abstract: Effective angular momentum functions from atmosphere, oceans, and terrestrial water storage are obtained from European Centre for Medium-Range Weather Forecasts atmospheric data and corresponding simulations with the Ocean Model for Circulation and Tides and the Land Surface and Discharge Model (LSDM). Mass exchanges among the subsystems are realized by means of freshwater fluxes, causing the total ocean mass to vary predominantly annually. Variations in total ocean mass affect the oceanic excitations of the annual wobble by almost 1 milliarc second (mas) for both prograde and retrograde components, whereas the motion term contributions of terrestrial water flow derived from LSDM are found to be 3 orders of magnitude smaller. Since differences to geodetic excitations are not substantially reduced and regional decompositions demonstrate the large spatial variability of contributions to seasonal polar motion excitation that compensate each other when integrated globally, it is concluded that the closure of the seasonal excitation budget is still inhibited by remaining model errors in all subsystems.
Keywords: Earth rotation variations., Geodesy and Gravity: Earth rotation variations, Geodesy and Gravity: Mass balance
ECCO Products Used: ECCO-KFS
Other URLs:
Kroner, C; Thomas, M; Dobslaw, H; Abe, M; Weise, A (2009). Seasonal effects of non-tidal oceanic mass shifts in observations with superconducting gravimeters, Journal of Geodynamics, 3-5 (48), 354-359, 10.1016/j.jog.2009.09.009.
Title: Seasonal effects of non-tidal oceanic mass shifts in observations with superconducting gravimeters
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Kroner, C; Thomas, M; Dobslaw, H; Abe, M; Weise, A
Year: 2009
Formatted Citation: Kroner, C., M. Thomas, H. Dobslaw, M. Abe, and A. Weise, 2009: Seasonal effects of non-tidal oceanic mass shifts in observations with superconducting gravimeters. Journal of Geodynamics, 48(3-5), 354-359, doi:10.1016/j.jog.2009.09.009
Abstract: in order to achieve a consistent combination of terrestrial and satellite-derived (GRACE) gravity field variations reductions of systematic perturbations must be applied to both data sets. At the same time evidence needs to be provided that these reductions are both necessary and sufficient. Based on the OMCT and the ECCO model the gravity effect of non-tidal oceanic mass shifts is computed for various sites equipped with a superconducting gravimeter (SG) and esp. the long-periodic contributions are studied. With these oceanic models the dynamic ocean response to atmospheric pressure loading is automatically computed, and thus goes beyond the more simplistic concepts of an inverted barometer, or alternately a rigid ocean, which is a clear advantage. The findings so far are ambiguous: for instance the systematic seasonal change of about 10 nm/s(2) in gravity for mid-European stations is presently not found in the observed gravity variations. Generally, the order of magnitude of the total effect of 22-27 nm/s(2) is surprisingly large for inland stations. in some data sections the reduction leads to the removal of some of the larger residuals. The results obtained for the South-African station Sutherland differ. Here the modelled seasonal variation caused by the non-tidal oceanic mass redistribution and gravity residuals generally correlate, and thus by the reduction an improvement of the signal-to-noise ratio in the gravity observations is achieved. An explanation for the different results might be found in the global hydrological models. Such a model is needed in order to remove the effect of large-scale variations in continental water storage in the gravity observations. This reduction plays a greater role for European stations than for the South African site. A critical impact of the land-sea-mask used in the oceanic models and the subsequent insufficient resolution of the North and Baltic Sea on the computations at the mid-European sites could not be confirmed. From a comparison between the OMCT and the ECCO model substantial discrepancies in some regions of the earth emerge, while both predict variations at inland stations in Europe, South Africa, and Asia of similar magnitude. We currently hesitate to recommend including this reduction in the routine processing of SG data because the seasonal order of magnitude for inland stations is unexpectedly large and partly significant deviations between the modelled oceanic effects exist. if the order of magnitude proves to be correct universally, this reduction has to be applied. (C) 2009 Elsevier Ltd. All rights reserved.
Keywords: GRACE validation, Long-periodic gravity variations, Ocean models, Superconducting gravimetry, atmospheric-pressure, earth, field, grace, ground gravity measurements, model, parameters, reduction, tides, validation
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
van der Werf, Petra M.; Schouten, M W; van Leeuwen, P J; Ridderinkhof, H; de Ruijter, W P M (2009). Observation and origin of an interannual salinity anomaly in the Mozambique Channel, Journal of Geophysical Research: Oceans, C3 (114), 10.1029/2008JC004911.
Title: Observation and origin of an interannual salinity anomaly in the Mozambique Channel
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): van der Werf, Petra M.; Schouten, M W; van Leeuwen, P J; Ridderinkhof, H; de Ruijter, W P M
Year: 2009
Formatted Citation: van der Werf, P. M., M. W. Schouten, P. J. van Leeuwen, H. Ridderinkhof, and W. P. M. de Ruijter, 2009: Observation and origin of an interannual salinity anomaly in the Mozambique Channel. J. Geophys. Res. Ocean., 114(C3), doi:10.1029/2008JC004911
Abstract: A positive salinity anomaly of 0.2 PSU was observed between 50 and 200 m over the years 2000-2001 across the Mozambique Channel at a section at 17°S which was repeated in 2003, 2005, 2006, and 2008. Meanwhile, a moored array is continued from 2003 to 2008. This anomaly was most distinct showing an interannual but nonseasonal variation. The possible origin of the anomaly is investigated using output from three ocean general circulation models (Estimating the Circulation and Climate of the Ocean, Ocean Circulation and Climate Advanced Modeling, and Parallel Ocean Program). The most probable mechanism for the salinity anomaly is the anomalous inflow of subtropical waters caused by a weakening of the northern part of the South Equatorial Current by weaker trade winds. This mechanism was found in all three numerical models. In addition, the numerical models indicate a possible salinization of one of the source water masses to the Mozambique Channel as an additional cause of the anomaly. The anomaly propagated southward into the Agulhas Current and northward along the African coast.
Keywords: 4223 Descriptive and regional oceanography, 4255 Numerical modeling, 4572 Upper ocean and mixed layer processes, Mozambique Channel, interannual variability, salinity anomaly
ECCO Products Used: ECCO-KFS
Other URLs:
Seitz, Florian; Krügel, Manuela (2009). Inverse Model Approach for vertical Load Deformations in Consideration of Crustal Inhomogeneities, Geodetic Reference Frames, 23-29, 10.1007/978-3-642-00860-3_4.
Title: Inverse Model Approach for vertical Load Deformations in Consideration of Crustal Inhomogeneities
Type: Book Section
Publication: Geodetic Reference Frames
Author(s): Seitz, Florian; Krügel, Manuela
Year: 2009
Formatted Citation: Seitz, F., and M. Krügel, 2009: Inverse Model Approach for vertical Load Deformations in Consideration of Crustal Inhomogeneities. Geodetic Reference Frames, H. Drewes, Eds., Springer, 23-29, doi:10.1007/978-3-642-00860-3_4
Abstract: Geodetic Reference Frames
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Brzeziński, Aleksander; Nastula, Jolanta; Kołaczek, Barbara (2009). Seasonal excitation of polar motion estimated from recent geophysical models and observations, Journal of Geodynamics, 3-5 (48), 235-240, 10.1016/j.jog.2009.09.021.
Title: Seasonal excitation of polar motion estimated from recent geophysical models and observations
Type: Journal Article
Publication: Journal of Geodynamics
Author(s): Brzeziński, Aleksander; Nastula, Jolanta; Kołaczek, Barbara
Year: 2009
Formatted Citation: Brzeziński, A., J. Nastula, and B. Kołaczek, 2009: Seasonal excitation of polar motion estimated from recent geophysical models and observations. Journal of Geodynamics, 48(3-5), 235-240, doi:10.1016/j.jog.2009.09.021
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Ma, Jin; Zhou, Yong-Hong; Liao, De-Chun; Chen, Jian-Li (2009). Excitation of Chandler Wobble by Pacific, Indian and Atlantic Oceans from 1980 to 2005, Chinese Astronomy and Astrophysics, 4 (33), 410-420, 10.1016/j.chinastron.2009.09.007.
Title: Excitation of Chandler Wobble by Pacific, Indian and Atlantic Oceans from 1980 to 2005
Type: Journal Article
Publication: Chinese Astronomy and Astrophysics
Author(s): Ma, Jin; Zhou, Yong-Hong; Liao, De-Chun; Chen, Jian-Li
Year: 2009
Formatted Citation: Ma, J., Y. Zhou, D. Liao, and J. Chen, 2009: Excitation of Chandler Wobble by Pacific, Indian and Atlantic Oceans from 1980 to 2005. Chinese Astronomy and Astrophysics, 33(4), 410-420, doi:10.1016/j.chinastron.2009.09.007
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Halkides, D J; Lee, Tong (2009). Mechanisms controlling seasonal-to-interannual mixed layer temperature variability in the southeastern tropical Indian Ocean, Journal of Geophysical Research: Oceans, C2 (114), 10.1029/2008JC004949.
Title: Mechanisms controlling seasonal-to-interannual mixed layer temperature variability in the southeastern tropical Indian Ocean
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Halkides, D J; Lee, Tong
Year: 2009
Formatted Citation: Halkides, D. J., and T. Lee, 2009: Mechanisms controlling seasonal-to-interannual mixed layer temperature variability in the southeastern tropical Indian Ocean. J. Geophys. Res. Ocean., 114(C2), doi:10.1029/2008JC004949
Abstract: We use an Estimating the Circulation and Climate of the Ocean assimilation product to investigate seasonal-interannual mixed layer temperature (MLT) budgets in the southeastern tropical Indian Ocean (SETIO) during 1993-2006. We examine spatial inhomogeneity of the SETIO MLT budget, contrasting three subregions with different forcing/circulation characteristics to better understand the area mean budget over the full SETIO. The subregions are the equatorial zone (box 1), the Sumatra-Java upwelling zone (box 2), and east of the thermocline ridge (box 3). Seasonally, surface heat flux dominates MLT in all regions; advection and subsurface processes generally play secondary roles. On interannual scales, surface heat flux makes major contributions in all three boxes to termination of SETIO cooling associated with the Indian Ocean Zonal/Dipole Mode. Ocean dynamics show vital differences between regions: Subsurface processes cool box 1 and 2 but warm box 3. Horizontal advection warms box 1 but cools box 2 and 3. Averaging the MLT budget over the SETIO obscures regional physics. We explain spatial variations of the SETIO MLT budget in terms of differences in forcing, circulation, MLT distribution, and mixed layer and barrier layer thicknesses. We also examine SETIO MLT budget differences during 1994, 1997, and 2006, years exhibiting notable SETIO cooling events. In box 1, horizontal advection dominates warming after the 1994 and 2006 coolings, while in 1997, surface heat flux dominates warming. In box 2, cooling peaks earlier in 1994 than in 1997 and 2006 because of subsurface processes. Last, we show that the MLT budget is very different from heat budgets for fixed depth layers (e.g., the top 50-60 m).
Keywords: 4215 Climate and interannual variability, 4504 Air/sea interactions, 4572 Upper ocean and mixed layer processes, IOZDM, MLT, SETIO
ECCO Products Used: ECCO-KFS
Other URLs:
Cummings, James; Bertino, Laurent; Brasseur, Pierre; Fukumori, Ichiro; Kamachi, Masafumi; Martin, Matthew J; Mogensen, Kristian; Oke, Peter; Testut, Charles E; Verron, Jacques; Weaver, Anthony (2009). Ocean Data Assimilation Systems for GODAE, Oceanography, 3 (22), 96-109, 10.5670/oceanog.2009.69.
Title: Ocean Data Assimilation Systems for GODAE
Type: Journal Article
Publication: Oceanography
Author(s): Cummings, James; Bertino, Laurent; Brasseur, Pierre; Fukumori, Ichiro; Kamachi, Masafumi; Martin, Matthew J; Mogensen, Kristian; Oke, Peter; Testut, Charles E; Verron, Jacques; Weaver, Anthony
Year: 2009
Formatted Citation: Cummings, J. and Coauthors, 2009: Ocean Data Assimilation Systems for GODAE. Oceanography, 22(3), 96-109, doi:10.5670/oceanog.2009.69
Abstract: Ocean data assimilation has matured to the point that observations are now routinely combined with model forecasts to produce a variety of ocean products. Approaches to ocean data assimilation vary widely both in terms of the sophistication of the method and the observations assimilated, and also in terms of specification of the forecast error covariances, model biases, observation errors, and quality-control procedures. In this paper, we describe some of the ocean data assimilation systems that have been developed within the Global Ocean Data Assimilation Experiment (GODAE) community. We discuss assimilation methods, observations assimilated, and techniques used to specify error covariances. In addition, we describe practical implementation aspects and present analysis performance results for some of the analysis systems. Finally, we describe plans for improving the assimilation systems in the post-GODAE time period beyond 2008.
Keywords: kalman filter, model, salinity, smoother, temperature
ECCO Products Used: ECCO-KFS
Other URLs:
Fernández, L.I (2009). Analysis of Geophysical Variations of the C20 Coefficient of the Geopotential, Observing our Changing Earth (133), 493-500, 10.1007/978-3-540-85426-5_59.
Title: Analysis of Geophysical Variations of the C20 Coefficient of the Geopotential
Type: Book Section
Publication: Observing our Changing Earth
Author(s): Fernández, L.I
Year: 2009
Formatted Citation: Fernández, L., 2009: Analysis of Geophysical Variations of the C20 Coefficient of the Geopotential. Observing our Changing Earth, Springer Berlin Heidelberg, 133, 493-500, doi:10.1007/978-3-540-85426-5_59
Abstract: The temporal variations of the C 20 spherical harmonic coefficient of the geopotential are estimated from the length of day (LOD) and compared with the C 20 variations due to geophysical contributions. In particular, we analyzed the agreement of the hydrological C 20 changes as estimated by the Land Dynamics Model (LaD) model. The computation spans between January 1980 and May 2004 for the hydrological model The contribution of atmospheric mass redistributions, along with the oceanic mass terms and solid Earth tides were removed from the geodetic C 20 time series for computing residuals. Afterward the hydrological influence was investigated After eliminating seasonal variations, the hydrological excitation seems to be not adequate to explain the inter-annual variations found in the C 20 residuals The luni-solar precession and nutation of the Earth depend on the dynamical flattening (H); which is related to the principal moments of inertia of the whole planet. H is linked to the C 20 coefficient of the Earth's potential, which is regularly determined by space geodetic techniques In this work, we also estimate the seasonal variations on H due to geophysical causes. These results should be useful to investigate the geophysical considerations in the computation of the IAU 2000 precesion-nutation model. © Springer-Verlag Berlin Heidelberg 2009.
Keywords: Earth rotation, Geopotencial, Gravity, Hydrology, Length-of-day
ECCO Products Used: ECCO-KFS
Other URLs: http://link.springer.com/10.1007/978-3-540-85426-5_59
Dushaw, Brian D. (2009). North Pacific Acoustic Laboratory: Analysis of Shadow Zone Arrivals and Acoustic Propagation in Numerical Ocean Models.
Title: North Pacific Acoustic Laboratory: Analysis of Shadow Zone Arrivals and Acoustic Propagation in Numerical Ocean Models
Type: Report
Publication:
Author(s): Dushaw, Brian D.
Year: 2009
Formatted Citation: Dushaw, B. D., 2009: North Pacific Acoustic Laboratory: Analysis of Shadow Zone Arrivals and Acoustic Propagation in Numerical Ocean Models., 12 pp.
Abstract: Over the decade 1996-2006, acoustic sources located off central California and north of Kauai transmitted to receivers distributed throughout the northeast and north central Pacific. Some of the observations included shadow-zone arrivals, that appear at travel times aligned with the lower cusps of the acoustic time front predicted by ray calculations, but with the depth of the receiver lies well below the depths of the predicted cusps. Several models for the temperature and salinity in the North Pacific Ocean were obtained and processed to enable simulations of acoustic propagation for comparison to the observations. New tools were developed to manage the large size of the model output, to extract and construct the relevant acoustic properties from the model output, and to make the acoustic calculations. Computer codes using ray tracing and the parabolic equation to calculate acoustic properties were significantly developed. The acoustic data show that WOA05 is a better estimate of the time-mean hydrography than either the JPL-ECCO or the POP estimates, which proved incapable of reproducing the observed acoustic arrival patterns.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: https://apps.dtic.mil/docs/citations/ADA494669
Gross, Richard S. (2009). An improved empirical model for the effect of long-period ocean tides on polar motion, Journal of Geodesy, 7 (83), 635-644, 10.1007/s00190-008-0277-y.
Title: An improved empirical model for the effect of long-period ocean tides on polar motion
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Gross, Richard S.
Year: 2009
Formatted Citation: Gross, R. S., 2009: An improved empirical model for the effect of long-period ocean tides on polar motion. Journal of Geodesy, 83(7), 635-644, doi:10.1007/s00190-008-0277-y
Abstract: Because the tide-raising potential is symmetric about the Earth's polar axis it can excite polar motion only by acting upon non-axisymmetric features of the Earth like the oceans. In fact, after removing atmospheric and non-tidal oceanic effects, polar motion excitation observations show a strong fortnightly tidal signal that is not completely explained by existing dynamical and empirical ocean tide models. So a new empirical model for the effect of the termensual (Mtm and mtm), fortnightly (Mf and mf), and monthly (Mm) tides on polar motion is derived here by fitting periodic terms at these tidal frequencies to polar motion excitation observations that span 2 January 1980 to 8 September 2006 and from which atmospheric and non-tidal oceanic effects have been removed. While this new empirical tide model can fully explain the observed fortnightly polar motion excitation signal during this time interval it would still be desirable to have a model for the effect of long-period ocean tides on polar motion that is determined from a dynamical ocean tide model and that is therefore independent of polar motion observations. © 2008 The Author(s).
Keywords: Atmospheric angular Momentum, Earth rotation, Ocean tides, Oceanic angular momentum, Polar motion
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
van der Werf, Petra M. (2009). Variability of the Mozambique Channel Throughflow.
Title: Variability of the Mozambique Channel Throughflow
Type: Thesis
Publication:
Author(s): van der Werf, Petra M.
Year: 2009
Formatted Citation: van der Werf, P. M., 2009: Variability of the Mozambique Channel Throughflow., 147 pp.
Abstract: The Mozambique Channel is an important link in the thermohaline circulation, as the variability in its throughflow affects the exchange between the Indian and South Atlantic Ocean south of Africa. In this dissertation, we study the variability of the Mozambique Channel throughflow in the range from eddy to interannual time scales and investigate the origin of this variability. A 4.2-year time series obtained by a mooring array in the Mozambique Channel at 17S was the main object of study, together with output from (Ocean General Circulation) models and satellite observations. Over the length of the observational time series, the mean volume transport 16.7 Sv southward, with daily values ranging between 45 Sv northward and 65 Sv southward. The throughflow is highly variable on a large range of time scales. Interannual variability was observed both in the volume transport and subsurface salinity in the Mozambique Channel. The amplitude of these variations was large, in the order of 9 Sv for the transport time series and about 0.2 PSU for a salinity anomaly. The interannual variability of the transport time series has a dominant period of two years. This signal is related to the Indian Ocean Dipole index and is transported via the South Equatorial Current. A negative phase of the dipole induces an increase of the southward transport in the Mozambique Channel with a lag of roughly one year. The salinity anomaly in the years 2000 - 2001 is related to the weakening of the northern part of the South Equatorial Current. This results in a reduced inflow of tropical, relatively fresh waters. The seasonal cycle of the transport has an amplitude of about 5 Sv and originates from upstream variability in the wind forcing west of the Mascarene Ridge. In the observations, this signal is overshadowed by variability at other frequencies. In Ocean General Circulation Models on the other hand, this frequency dominates the throughflow, as these models underrepresent variability at other, especially higher, frequencies. Variability at the eddy time scale is very strong in the observed volume transport time series. This is due to the formation of Mozambique Channel eddies around the location of the mooring section. The alternation between a strong southward current and eddies formed out of this current is causing the strong variability. In eddy resolving Ocean General Circulation Models, eddies are formed further upstream and therefore no alternation takes place at the mooring section. Nevertheless, the velocity structure of eddies in these models is quite well simulated. Using relatively simple models, it is shown that the estimated transport through the channel is very sensitive to the model setup and the simulation of barotropic and / or baroclinic variability. Rectification of the mean flow by this variability was strongest along the north and south boundary of the island. Also, the amount of rectification was sensitive to the basin setup.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: http://members.casema.nl/p.m.vanderwerf
Balmaseda, Magdalena Alonso; Alves, Oscar J.; Arribas, Alberto; Awaji, Toshiyuki; Behringer, David W.; Ferry, Nicolas; Fujii, Yosuke; Lee, Tong; Rienecker, Michele; Rosati, Tony; Stammer, Detlef (2009). Ocean Initialization for Seasonal Forecasts, Oceanography, 3 (22), 154-159.
Title: Ocean Initialization for Seasonal Forecasts
Type: Journal Article
Publication: Oceanography
Author(s): Balmaseda, Magdalena Alonso; Alves, Oscar J.; Arribas, Alberto; Awaji, Toshiyuki; Behringer, David W.; Ferry, Nicolas; Fujii, Yosuke; Lee, Tong; Rienecker, Michele; Rosati, Tony; Stammer, Detlef
Year: 2009
Formatted Citation: Balmaseda, M. A. and Coauthors, 2009: Ocean Initialization for Seasonal Forecasts. Oceanography, 22(3), 154-159, https://www.jstor.org/stable/24860997?seq=1#page_scan_tab_contents
Abstract: Several operational centers routinely issue seasonal forecasts of Earth's climate using coupled ocean-atmosphere models, which require near-real- time knowledge of the state of the global ocean. This paper reviews existing ocean analysis efforts aimed at initializing seasonal forecasts. We show that ocean data assimilation improves the skill of seasonal forecasts in many cases, although its impact can be overshadowed by errors in the coupled models. The current practice, known as "uncoupled" initialization, has the advantage of better knowledge of atmospheric forcing fluxes, but it has the shortcoming of potential initialization shock. In recent years, the idea of obtaining truly "coupled" initialization, where the different components of the coupled system are well balanced, has stimulated several research activities that will be reviewed in light of their application to seasonal forecasts.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0
Other URLs:
Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D. (2009). The use of gravimetric data from GRACE mission in the understanding of polar motion variations, Geophysical Journal International, 2 (178), 614-622, 10.1111/j.1365-246X.2009.04181.x.
Title: The use of gravimetric data from GRACE mission in the understanding of polar motion variations
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Seoane, L.; Nastula, J.; Bizouard, C.; Gambis, D.
Year: 2009
Formatted Citation: Seoane, L., J. Nastula, C. Bizouard, and D. Gambis, 2009: The use of gravimetric data from GRACE mission in the understanding of polar motion variations. Geophysical Journal International, 178(2), 614-622, doi:10.1111/j.1365-246X.2009.04181.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V1
Other URLs:
Qu, T D; Gao, S; Fukumori, I; Fine, R A; Lindstrom, E J (2009). Origin and Pathway of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint, Journal of Physical Oceanography, 8 (39), 1836-1853, 10.1175/2009jpo4045.1.
Title: Origin and Pathway of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Qu, T D; Gao, S; Fukumori, I; Fine, R A; Lindstrom, E J
Year: 2009
Formatted Citation: Qu, T. D., S. Gao, I. Fukumori, R. A. Fine, and E. J. Lindstrom, 2009: Origin and Pathway of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint. Journal of Physical Oceanography, 39(8), 1836-1853, doi:10.1175/2009jpo4045.1
Abstract: The origin and pathway of the thermostad water in the eastern equatorial Pacific Ocean, often referred to as the equatorial 13 degrees C Water, are investigated using a simulated passive tracer and its adjoint, based on circulation estimates of a global general circulation model. Results demonstrate that the source region of the 13 degrees C Water lies well outside the tropics. In the South Pacific, some 13 degrees C Water is formed northeast of New Zealand, confirming an earlier hypothesis on the water's origin. The South Pacific origin of the 13 degrees C Water is also related to the formation of the Eastern Subtropical Mode Water (ESTMW) and the Sub-Antarctic Mode Water (SAMW). The portion of the ESTMW and SAMW that eventually enters the density range of the 13 degrees C Water (25.8 < sigma(theta) < 26.6 kg m(-3)) does so largely by mixing. Water formed in the subtropics enters the equatorial region predominantly through the western boundary, while its interior transport is relatively small. The fresher North Pacific ESTMW and Central Mode Water (CMW) are also important sources of the 13 degrees C Water. The ratio of the southern versus the northern origins of the water mass is about 2 to 1 and tends to increase with time elapsed from its origin. Of the total volume of initially tracer-tagged water in the eastern equatorial Pacific, approximately 47.5% originates from depths above sigma(theta) = 25.8 kg m(-3) and 34.6% from depths below sigma(theta) = 26.6 kg m(-3), indicative of a dramatic impact of mixing on the route of subtropical water to becoming the 13 degrees C Water. Still only a small portion of the water formed in the subtropics reaches the equatorial region, because most of the water is trapped and recirculates in the subtropical gyre.
Keywords: climatology, intermediate, ocean circulation, overturning circulations, south-pacific, subsurface countercurrents, subtropical mode water, thermocline, tropical pacific, undercurrent
ECCO Products Used: ECCO-KFS;adjoint
URL:
Other URLs:
Dushaw, Brian D.; Worcester, P F; Munk, W H; Spindel, R C; Mercer, J A; Howe, B M; Metzger, K; Birdsall, T G; Andrew, R K; Dzieciuch, M A; Cornuelle, B D; Menemenlis, Dimitris (2009). A decade of acoustic thermometry in the North Pacific Ocean, Journal of Geophysical Research, C7 (114), C07021, 10.1029/2008JC005124.
Title: A decade of acoustic thermometry in the North Pacific Ocean
Type: Journal Article
Publication: Journal of Geophysical Research
Author(s): Dushaw, Brian D.; Worcester, P F; Munk, W H; Spindel, R C; Mercer, J A; Howe, B M; Metzger, K; Birdsall, T G; Andrew, R K; Dzieciuch, M A; Cornuelle, B D; Menemenlis, Dimitris
Year: 2009
Formatted Citation: Dushaw, B. D. and Coauthors, 2009: A decade of acoustic thermometry in the North Pacific Ocean. Journal of Geophysical Research, 114(C7), C07021, doi:10.1029/2008JC005124
Abstract: Over the decade 1996-2006, acoustic sources located off central California (1996-1999) and north of Kauai (1997-1999, 2002-2006) transmitted to receivers distributed throughout the northeast and north central Pacific. The acoustic travel times are inherently spatially integrating, which suppresses mesoscale variability and provides a precise measure of ray-averaged temperature. Daily average travel times at 4-day intervals provide excellent temporal resolution of the large-scale thermal field. The interannual, seasonal, and shorter-period variability is large, with substantial changes sometimes occurring in only a few weeks. Linear trends estimated over the decade are small compared to the interannual variability and inconsistent from path to path, with some acoustic paths warming slightly and others cooling slightly. The measured travel times are compared with travel times derived from four independent estimates of the North Pacific: (1) climatology, as represented by the World Ocean Atlas 2005 (WOA05); (2) objective analysis of the upper-ocean temperature field derived from satellite altimetry and in situ profiles; (3) an analysis provided by the Estimating the Circulation and Climate of the Ocean project, as implemented at the Jet Propulsion Laboratory (JPL-ECCO); and (4) simulation results from a high-resolution configuration of the Parallel Ocean Program (POP) model. The acoustic data show that WOA05 is a better estimate of the time mean hydrography than either the JPL-ECCO or the POP estimates, both of which proved incapable of reproducing the observed acoustic arrival patterns. The comparisons of time series provide a stringent test of the large-scale temperature variability in the models. The differences are sometimes substantial, indicating that acoustic thermometry data can provide significant additional constraints for numerical ocean models.
Keywords: 4215 Climate and interannual variability, 4259 Ocean acoustics, 4262 Ocean observing systems, 4263 Ocean predictability and prediction, acoustic thermometry, basin-scale variability, model testing
ECCO Products Used: ECCO-KFS
Other URLs: http://doi.wiley.com/10.1029/2008JC005124
Nastula, J.; Kolaczek, B.; Salstein, D. A. (2008). Comparison of hydrological and GRACE-based excitation functions of polar motion in the seasonal spectral band, Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007, 220-221.
Title: Comparison of hydrological and GRACE-based excitation functions of polar motion in the seasonal spectral band
Type: Conference Proceedings
Publication: Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007
Author(s): Nastula, J.; Kolaczek, B.; Salstein, D. A.
Year: 2008
Formatted Citation: Nastula, J., B. Kolaczek, and D. A. Salstein, 2008: Comparison of hydrological and GRACE-based excitation functions of polar motion in the seasonal spectral band. Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007, N. Capitaine, Eds. Observatoire de Paris, Paris, France, 220-221 pp. http://syrte.obspm.fr/journees2007/pdf/s4_28_Nastula.pdf.
Abstract: Understanding changes in the global balance of the Earths angular momentum due to the mass redistribution of geophysical fluids is needed to explain the observed polar motion. The impact of continental hydrologic signals, from land water, snow, and ice, on polar motion excitation (hydrological angular momentum-HAM), is still inadequately known. Although estimates of HAM have been made from several models of global hydrology based upon the observed distribution of surface water, snow, and soil moisture, the relatively sparse observation network and the presence of errors in the data and the geophysical fluid models preclude a full understanding of the HAM influence on polar motion variations. Recently the GRACE mission monitoring Earths time variable gravity field has allowed us to determine the mass term of polar motion excitation functions and compare them with the mass term derivable as a residual from the geodetic excitation functions and geophysical fluid motion terms on seasonal time scales. Differences between these mass terms in the years 2004 - 2005.5 are still on the order of 20 mas. Besides the overall mass excitation of polar motion comparisons with GRACE (RL04-release), we also intercompare the non-atmospheric, non-oceanic signals in the mass term of geodetic polar motion excitation with hydrological excitation of polar motion.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Korbacz, A; Nski, A Brzezi; Thomas, M (2008). Geophysical excitation of LOD/UT1 estimated from the output of the global circulation models of the atmosphere - ERA-40 reanalysis and of the ocean - OMCT, Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007", 188-191.
Title: Geophysical excitation of LOD/UT1 estimated from the output of the global circulation models of the atmosphere - ERA-40 reanalysis and of the ocean - OMCT
Type: Conference Proceedings
Publication: Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007"
Author(s): Korbacz, A; Nski, A Brzezi; Thomas, M
Year: 2008
Formatted Citation: Korbacz, A., A. B. Nski, and M. Thomas, 2008: Geophysical excitation of LOD/UT1 estimated from the output of the global circulation models of the atmosphere - ERA-40 reanalysis and of the ocean - OMCT. Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007", N. Capitaine, Eds. Observatoire de Paris, Paris, France, 188-191 pp. http://syrte.obspm.fr/jsr/journees2007/pdf/s4_12_Korbacz.pdf.
Abstract: We use new estimates of the global atmospheric and oceanic angular momenta (AAM, OAM) to study the influence on LOD/UT1. The AAM series was calculated from the output fields of the atmospheric general circulation model ERA-40 reanalysis. The OAM series is an outcome of global ocean model OMCT simulation driven by global fields of the atmospheric parameters from the ERA- 40 reanalysis. The excitation data cover the period between 1963 and 2001. Our calculations concern atmospheric and oceanic effects in LOD/UT1 over the periods between 20 days and decades. Results are compared to those derived from the alternative AAM/OAM data sets.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Cazes-Boezio, Gabriel; Menemenlis, Dimitris; Mechoso, Carlos R (2008). Impact of ECCO Ocean-State Estimates on the Initialization of Seasonal Climate Forecasts, Journal of Climate, 9 (21), 1929-1947, 10.1175/2007JCLI1574.1.
Title: Impact of ECCO Ocean-State Estimates on the Initialization of Seasonal Climate Forecasts
Type: Journal Article
Publication: Journal of Climate
Author(s): Cazes-Boezio, Gabriel; Menemenlis, Dimitris; Mechoso, Carlos R
Year: 2008
Formatted Citation: Cazes-Boezio, G., D. Menemenlis, and C. R. Mechoso, 2008: Impact of ECCO Ocean-State Estimates on the Initialization of Seasonal Climate Forecasts. J. Clim., 21(9), 1929-1947, doi:10.1175/2007JCLI1574.1
Abstract: The impact of ocean-state estimates generated by the consortium for Estimating the Circulation and Climate of the Ocean (ECCO) on the initialization of a coupled general circulation model (CGCM) for seasonal climate forecasts is examined. The CGCM consists of the University of California, Los Angeles, Atmospheric GCM (UCLA AGCM) and an ECCO ocean configuration of the Massachusetts Institute of Technology GCM (MITgcm). The forecasts correspond to ensemble seasonal hindcasts for the period 1993-2001. For the forecasts, the ocean component of the CGCM is initialized in either early March or in early June using ocean states provided either by an unconstrained forward ocean integration of the MITgcm (the "baseline" hindcasts) or by data-constrained ECCO results (the "ECCO" hindcasts). Forecast skill for both the baseline and the ECCO hindcasts is significantly higher than persistence and compares well with the skill of other state-of-the art CGCM forecast systems. For March initial conditions, the standard errors of sea surface temperature (SST) anomalies in ECCO hindcasts (relative to observed anomalies) are up to 1°C smaller than in the baseline hindcasts over the central and eastern equatorial Pacific (150°-120°W). For June initial conditions, the errors of ECCO hindcasts are up to 0.5°C smaller than in the baseline hindcasts. The smaller standard error of the ECCO hindcasts is, in part, due to a more realistic equatorial thermocline structure of the ECCO initial conditions. This study confirms the value of physically consistent ocean-state estimation for the initialization of seasonal climate forecasts.
Keywords: Hindcasts, Model initialization, Ocean models, Sea surface temperature, Seasonal forecasting
ECCO Products Used: ECCO-KFS
Other URLs:
Zhong, Min; Yan, Hao-ming (2008). Excitation of Annual Polar Wobble by Global Oceans, Chinese Astronomy and Astrophysics, 1 (32), 91-99, 10.1016/j.chinastron.2008.01.009.
Title: Excitation of Annual Polar Wobble by Global Oceans
Type: Journal Article
Publication: Chinese Astronomy and Astrophysics
Author(s): Zhong, Min; Yan, Hao-ming
Year: 2008
Formatted Citation: Zhong, M., and H. Yan, 2008: Excitation of Annual Polar Wobble by Global Oceans. Chinese Astronomy and Astrophysics, 32(1), 91-99, doi:10.1016/j.chinastron.2008.01.009
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V1
Other URLs:
Chen, J. L.; Wilson, C. R. (2008). Low degree gravity changes from GRACE, earth rotation, geophysical models, and satellite laser ranging, Journal of Geophysical Research: Solid Earth, 6 (113), 1-9, 10.1029/2007JB005397.
Title: Low degree gravity changes from GRACE, earth rotation, geophysical models, and satellite laser ranging
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Chen, J. L.; Wilson, C. R.
Year: 2008
Formatted Citation: Chen, J. L., and C. R. Wilson, 2008: Low degree gravity changes from GRACE, earth rotation, geophysical models, and satellite laser ranging. Journal of Geophysical Research: Solid Earth, 113(6), 1-9, doi:10.1029/2007JB005397
Abstract: [1] Several independent time series of variations ΔC21, ΔS21, and ΔC20 in Earth's gravity field are compared for the period April 2002 to May 2007. We examine estimates from the Gravity Recovery and Climate Experiment (GRACE), Earth rotation variations, climate models, and satellite laser ranging (SLR). Recently released GRACE solutions show significant improvement relative to earlier results, especially for ΔC21 and ΔS21. At the annual period, all estimates agree remarkably well, and good correlation is found among time series at intraseasonal periods. In general, Earth rotation values for ΔC21 and ΔS21, and SLR values for ΔC20 agree best with GRACE estimates. GRACE ΔC20 time series are contaminated by aliased ocean tide model errors. SLR ΔC21 and ΔS21 time series have been reported without an ocean pole tide (OPT) correction and with an older Solid Earth Pole Tide (SEPT) model. After correcting for OPT and SEPT deficiencies, SLR ΔC21 and ΔS21 time series show improved agreement with other estimates.
Keywords: Earth rotation, GRACE, SLR, doi:10.1029/2007JB005397, geophysical models, gravity, http://dx.doi.org/10.1029/2007JB005397
ECCO Products Used: ECCO-KFS
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Göttl, Franziska (2008). Earth rotation variations from geometric , gravimetric and altimetric observations and geophysical models.
Title: Earth rotation variations from geometric , gravimetric and altimetric observations and geophysical models
Type: Report
Publication:
Author(s): Göttl, Franziska
Year: 2008
Formatted Citation: Göttl, F., 2008: Earth rotation variations from geometric , gravimetric and altimetric observations and geophysical models., München, Germany(84), 16 pp. https://mediatum.ub.tum.de/doc/1300697/file.pdf.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Kuo, C Y; Shum, C K; Guo, J Y; Yi, Y C; Braun, A; Fukumori, I; Matsumoto, K; Sato, T; Shibuya, K (2008). Southern Ocean mass variation studies using GRACE and satellite altimetry, Earth Planets and Space, 5 (60), 477-485, 10.1186/BF03352814.
Title: Southern Ocean mass variation studies using GRACE and satellite altimetry
Type: Journal Article
Publication: Earth Planets and Space
Author(s): Kuo, C Y; Shum, C K; Guo, J Y; Yi, Y C; Braun, A; Fukumori, I; Matsumoto, K; Sato, T; Shibuya, K
Year: 2008
Formatted Citation: Kuo, C. Y. and Coauthors, 2008: Southern Ocean mass variation studies using GRACE and satellite altimetry. Earth Planets and Space, 60(5), 477-485, doi:10.1186/BF03352814
Abstract: The Southern Ocean is a major link between the world oceans via complicated processes associated with the melting and accumulation of the vast Antarctic ice sheets and the surrounding sea ice. The Southern Ocean sea level is poorly observed except from recent near-polar orbiting space geodetic satellites. In this study, the Southern Ocean mass variations at the seasonal scale are compared using three independent data sets: (1) the Gravity Recovery And Climate Recovery Experiment (GRACE) observed ocean bottom pressure (OBP), (2) steric-corrected satellite altimetry (ENVISAT) and, (3) the Estimating the Circulation and Climate of the Ocean (ECCO) model OBP data. The height difference between sea level derived from altimetry and steric sea level contains the vertical displacement of the Earth surface due to elastic loading. Here we provide a formulation of this loading term which has not been considered previously in other studies and demonstrate that it is not negligible, especially for regional studies. In this study, we first conduct a global comparison using steric-corrected JASON-1 altimetry with GRACE to validate our technique and to compare with recent studies. The global ocean mass variation comparison shows excellent agreement with high correlation (similar to 0.81) and with discrepancies at 3-5 mm RMS. However, the discrepancies in the Southern Ocean are much larger at 12-17 mm RMS. The mis-modeling of geocenter variations and the second degree zonal harmonic (J(2)) degrade the accuracy of GRACE-derived mass variations, and the choice of ocean temperature data sets and neglecting the loading correction on altimetry affect the OBP comparisons between GRACE and altimetry. This study indicates that the satellite observations (GRACE and ENVISAT) are capable of providing an improved constraint of oceanic mass variations in the Southern Ocean.
Keywords: altimetry, antarctic circumpolar current, grace, gravity, models, southern ocean, steric sea-level, variability, volume
ECCO Products Used: ECCO-KFS
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Seoane, L.; Bizouard, C.; Gambis, D. (2008). Polar motion interpretation using gravimetric observations, Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007".
Title: Polar motion interpretation using gravimetric observations
Type: Conference Proceedings
Publication: Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007"
Author(s): Seoane, L.; Bizouard, C.; Gambis, D.
Year: 2008
Formatted Citation: Seoane, L., C. Bizouard, and D. Gambis, 2008: Polar motion interpretation using gravimetric observations. Proceedings of the "Journées Systèmes de Référence Spatio-temporels 2007", Paris, France
Abstract: Polar motion is interpreted as the effect of i) the Earth's inertia moment changes asso- ciated with the so-called mass term of the Earth's angular momentum ii) the Earth's relative angular momentum in the terrestrial frame. Thanks to the GRACE mission and in a lesser extent to LAGEOS missions, the mass term is determined since 2002, independently from any geophysical model. Besides the modeled excitations of the polar motion, i.e the atmospheric angular momentum (AAM), the Oceanic Angular Momentum (OAM), the Hydrological Angular Momentum (HAM), this gravimetric mass term is a new kind of information which can be matched to the observed excitation of the polar motion after removal of the effect of the relative angular momentum, mostly caused by the wind and the oceanic cur- rents. Such comparison, already performed by various authors, is updated for the last releases (RL04) of the gravity field changes i.e. those of the GFZ, CSR, JPL and explored for the mixed LAGEOS-GRACE solution of the GRGS. We confirm that a fair general agreement, especially for the y-component of the equatorial excitation. After removing the modeled oceanic and atmospheric excitations from the signals, we obtain the non-modeled excitation, mostly of hydrological nature; this allows us to compare them to the existing hydrological models, differences might comes from others Earth's phenomena, for example, earthquakes.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: https://www.researchgate.net/profile/L_Seoane/publication/228422406_Polar_motion_interpretation_using_gravimetric_observations/links/54520d330cf2
Cabanes, C; Lee, T; Fu, L L (2008). Mechanisms of interannual variations of the meridional overturning circulation of the North Atlantic Ocean, Journal of Physical Oceanography, 2 (38), 467-480, 10.1175/2007jpo3726.1.
Title: Mechanisms of interannual variations of the meridional overturning circulation of the North Atlantic Ocean
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Cabanes, C; Lee, T; Fu, L L
Year: 2008
Formatted Citation: Cabanes, C., T. Lee, and L. L. Fu, 2008: Mechanisms of interannual variations of the meridional overturning circulation of the North Atlantic Ocean. Journal of Physical Oceanography, 38(2), 467-480, doi:10.1175/2007jpo3726.1
Abstract: The authors investigate the nature of the interannual variability of the meridional overturning circulation (MOC) of the North Atlantic Ocean using an Estimating the Circulation and Climate of the Ocean (ECCO) assimilation product for the period of 1993-2003. The time series of the first empirical orthogonal function of the MOC is found to be correlated with the North Atlantic Oscillation (NAO) index, while the associated circulation anomalies correspond to cells extending over the full ocean depth. Model sensitivity experiments suggest that the wind is responsible for most of this interannual variability, at least south of 40 degrees N. A dynamical decomposition of the meridional streamfunction allows a further look into the mechanisms. In particular, the contributions associated with 1) the Ekman flow and its depth-independent compensation, 2) the vertical shear flow, and 3) the barotropic gyre flowing over zonally varying topography are examined. Ekman processes are found to dominate the shorter time scales (1.5-3 yr), while for longer time scales (3-10 yr) the MOC variations associated with vertical shear flow are of greater importance. The latter is primarily caused by heaving of the pycnocline in the western subtropics associated with the stronger wind forcing. Finally, how these changes in the MOC affect the meridional heat transport (MHT) is examined. It is found that overall, Ekman processes explain a larger part of interannual variability (3-10 yr) for MHT (57%) than for the MOC (33%).
Keywords: heat-transport, model, pacific-ocean, sea-surface height, variability
ECCO Products Used: ECCO-KFS
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Cheng, Xuhua; Qi, Yiquan; Zhou, Wen (2008). Trends of sea level variations in the Indo-Pacific warm pool, Global and Planetary Change, 1 (63), 57-66, 10.1016/j.gloplacha.2008.06.001.
Title: Trends of sea level variations in the Indo-Pacific warm pool
Type: Journal Article
Publication: Global and Planetary Change
Author(s): Cheng, Xuhua; Qi, Yiquan; Zhou, Wen
Year: 2008
Formatted Citation: Cheng, X., Y. Qi, and W. Zhou, 2008: Trends of sea level variations in the Indo-Pacific warm pool. Global and Planetary Change, 63(1), 57-66, doi:10.1016/j.gloplacha.2008.06.001
Abstract: The long-term trends of sea level height in the Indo-Pacific warm pool (IPWP) were examined using merged altimetry data, and possible mechanisms were studied using multiple datasets. Sea level in the IPWP and the Western Pacific warm pool (WPWP) has distinct interannual variabilities related to ENSO (El Niño-Southern Oscillation) event. The mean sea level in the IPWP has a rising rate of 4.5 mm/yr over the 1993-2005 period, while the WPWP and the Indian Ocean warm pool (IOWP) have rising rate of 6.0 mm/yr and 1.6 mm/yr respectively. The trends of thermosteric sea level were also examined using Ishii data and MITgcm assimilation data and the results indicate that thermal change of upper layer has a significant contribution to the sea level variations in the WPWP. But the thermosteric sea level has little contribution to sea level change in the IOWP region. Apart from thermal contribution, the contribution of precipitation and evaporation to sea level change were also examined. © 2008 Elsevier B.V. All rights reserved.
Keywords: Indo-Pacific warm pool, merged altimetry data, sea level variations, thermosteric sea level
ECCO Products Used: ECCO-KFS
URL:
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Göttl, F; Seitz, F (2008). Contribution of Non-Tidal Oceanic Mass Variations to Polar Motion Determined from Space Geodesy and Ocean Data, Observing our Changing Earth, 439-445, 10.1007/978-3-540-85426-5_53.
Title: Contribution of Non-Tidal Oceanic Mass Variations to Polar Motion Determined from Space Geodesy and Ocean Data
Type: Book Section
Publication: Observing our Changing Earth
Author(s): Göttl, F; Seitz, F
Year: 2008
Formatted Citation: Göttl, F., and F. Seitz, 2008: Contribution of Non-Tidal Oceanic Mass Variations to Polar Motion Determined from Space Geodesy and Ocean Data. Observing our Changing Earth, Springer Berlin Heidelberg, 439-445, doi:10.1007/978-3-540-85426-5_53
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Yulaeva, E.; Kanamitsu, M.; Roads, J. (2008). The ECPC Coupled Prediction Model, Monthly Weather Review, 1 (136), 295-316, 10.1175/2007MWR1929.1.
Title: The ECPC Coupled Prediction Model
Type: Journal Article
Publication: Monthly Weather Review
Author(s): Yulaeva, E.; Kanamitsu, M.; Roads, J.
Year: 2008
Formatted Citation: Yulaeva, E., M. Kanamitsu, and J. Roads, 2008: The ECPC Coupled Prediction Model. Monthly Weather Review, 136(1), 295-316, doi:10.1175/2007MWR1929.1
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Munekane, H. (2007). Ocean mass variations from GRACE and tsunami gauges, Journal of Geophysical Research, B7 (112), B07403, 10.1029/2006JB004618.
Title: Ocean mass variations from GRACE and tsunami gauges
Type: Journal Article
Publication: Journal of Geophysical Research
Author(s): Munekane, H.
Year: 2007
Formatted Citation: Munekane, H., 2007: Ocean mass variations from GRACE and tsunami gauges. Journal of Geophysical Research, 112(B7), B07403, doi:10.1029/2006JB004618
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Cheng, Xuhua; Qi, Yiquan (2007). Trends of sea level variations in the South China Sea from merged altimetry data, Global and Planetary Change, 3-4 (57), 371-382, 10.1016/j.gloplacha.2007.01.005.
Title: Trends of sea level variations in the South China Sea from merged altimetry data
Type: Journal Article
Publication: Global and Planetary Change
Author(s): Cheng, Xuhua; Qi, Yiquan
Year: 2007
Formatted Citation: Cheng, X., and Y. Qi, 2007: Trends of sea level variations in the South China Sea from merged altimetry data. Global and Planetary Change, 57(3-4), 371-382, doi:10.1016/j.gloplacha.2007.01.005
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Kim, S B; Lee, T; Fukumori, I (2007). Mechanisms controlling the interannual variation of mixed layer temperature averaged over the Nino-3 region, Journal of Climate, 15 (20), 3822-3843, 10.1175/Jcli4206.1.
Title: Mechanisms controlling the interannual variation of mixed layer temperature averaged over the Nino-3 region
Type: Journal Article
Publication: Journal of Climate
Author(s): Kim, S B; Lee, T; Fukumori, I
Year: 2007
Formatted Citation: Kim, S. B., T. Lee, and I. Fukumori, 2007: Mechanisms controlling the interannual variation of mixed layer temperature averaged over the Nino-3 region. J. Clim., 20(15), 3822-3843, doi:10.1175/Jcli4206.1
Abstract: Processes controlling the interannual variation of mixed layer temperature (MLT) averaged over the Nino-3 domain (5 degrees N-5 degrees S, 150 degrees-90 degrees W) are studied using an ocean data assimilation product that covers the period of 1993-2003. The overall balance is such that surface heat flux opposes the MLT change but horizontal advection and subsurface processes assist the change. Advective tendencies are estimated here as the temperature fluxes through the domain's boundaries, with the boundary temperature referenced to the domain-averaged temperature to remove the dependence on temperature scale. This allows the authors to characterize external advective processes that warm or cool the water within the domain as a whole. The zonal advective tendency is caused primarily by large-scale advection of warm-pool water through the western boundary of the domain. The meridional advective tendency is contributed to mostly by Ekman current advecting large-scale temperature anomalies through the southern boundary of the domain. Unlike many previous studies, the subsurface processes that consist of vertical mixing and entrainment are explicitly evaluated. In particular, a rigorous method to estimate entrainment allows an exact budget closure. The vertical mixing across the mixed layer (ML) base has a contribution in phase with the MLT change. The entrainment tendency due to the temporal change in ML depth is negligible compared to other subsurface processes. The entrainment tendency by vertical advection across the ML base is dominated by large-scale changes in upwelling and the temperature of upwelling water. Tropical instability waves (TIWs) result in smaller-scale vertical advection that warms the domain during La Nina cooling events. However, such a warming tendency is overwhelmed by the cooling tendency associated with the large-scale upwelling by a factor of 2. In summary, all the balance terms are important in the MLT budget except the entrainment due to lateral induction and temporal variation in ML depth. All three advective tendencies are primarily caused by large-scale and low-frequency processes, and they assist the Nino-3 MLT change. When the advective tendencies are evaluated by spatially averaging the conventional local advection of temperature, the apparent effects of currents with spatial scales smaller than the domain (such as TIWs) become very important as they redistribute heat within the Nino-3 domain. As a result, for example, the averaged zonal advective tendency counteracts rather than assists the Nino-3 MLT change. However, such internal redistribution of heat does not represent external processes that control the domain-averaged MLT.
Keywords: 1997-98 el-nino, atlantic-ocean, circulation model, conceptual-model, equatorial pacific-ocean, heat-budget, part i, sea-surface temperature, tropical instability waves, variability
ECCO Products Used: ECCO-KFS
URL:
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Fernández, L. I.; Schuh, H.; Schmidt, M.; Seitz, F. (2007). Effects of inter-annual water storage variations on polar motion, Geophysical Journal International, 1 (169), 12-18, 10.1111/j.1365-246X.2006.03304.x.
Title: Effects of inter-annual water storage variations on polar motion
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Fernández, L. I.; Schuh, H.; Schmidt, M.; Seitz, F.
Year: 2007
Formatted Citation: Fernández, L. I., H. Schuh, M. Schmidt, and F. Seitz, 2007: Effects of inter-annual water storage variations on polar motion. Geophysical Journal International, 169(1), 12-18, doi:10.1111/j.1365-246X.2006.03304.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Masaki, Yoshimitsu (2007). Expected Seasonal Excitations of Earth Rotation by Unmodeled Geophysical Fluids, Bulletin of the Geographical Survey Institute (54), 65-73.
Title: Expected Seasonal Excitations of Earth Rotation by Unmodeled Geophysical Fluids
Type: Journal Article
Publication: Bulletin of the Geographical Survey Institute
Author(s): Masaki, Yoshimitsu
Year: 2007
Formatted Citation: Masaki, Y., 2007: Expected Seasonal Excitations of Earth Rotation by Unmodeled Geophysical Fluids. Bulletin of the Geographical Survey Institute, 54, 65-73, http://www.gsi.go.jp/common/000001215.pdf
Abstract: We compare modeled (atmospheric and oceanic) seasonal excitations of the Earth rotation with the observed ones and estimate expected seasonal excitations from unmodeled geophysical fluids, primarily attributable to the hydrologic excitations. Through budget analysis of the seasonal excitations, maximum deficits in geophysical excitations occur in boreal spring to summer. If we assume a mass source on the Earth to compensate the deficits, a positive mass excess is expected around longitudes 90°E to 120°E or from 60°W to 90°W. Observation of the Earth rotation is useful for constraining geophysical excitations with some errors. The interannual variability in seasonal excitations also affects the estimation of Chandler parameters.
Keywords:
ECCO Products Used: ECCO-KFS
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Zlotnicki, V; Wahr, J; Fukumori, I; Song, Y T (2007). Antarctic circumpolar current transport variability during 2003-05 from GRACE, Journal of Physical Oceanography, 2 (37), 230-244, 10.1175/Jpo3009.1.
Title: Antarctic circumpolar current transport variability during 2003-05 from GRACE
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Zlotnicki, V; Wahr, J; Fukumori, I; Song, Y T
Year: 2007
Formatted Citation: Zlotnicki, V., J. Wahr, I. Fukumori, and Y. T. Song, 2007: Antarctic circumpolar current transport variability during 2003-05 from GRACE. Journal of Physical Oceanography, 37(2), 230-244, doi:10.1175/Jpo3009.1
Abstract: Gravity Recovery and Climate Experiment ( GRACE) gravity data spanning January 2003 - November 2005 are used as proxies for ocean bottom pressure ( BP) averaged over 1 month, spherical Gaussian caps 500 km in radius, and along paths bracketing the Antarctic Circumpolar Current's various fronts. The GRACE BP signals are compared with those derived from the Estimating the Circulation and Climate of the Ocean ( ECCO) ocean modeling - assimilation system, and to a non-Boussinesq version of the Regional Ocean Model System ( ROMS). The discrepancy found between GRACE and the models is 1.7 cm(H2O) ( 1 cm(H2O) similar to 1 hPa), slightly lower than the 1.9 cm(H2O) estimated by the authors independently from propagation of GRACE errors. The northern signals are weak and uncorrelated among basins. The southern signals are strong, with a common seasonality. The seasonal cycle GRACE data observed in the Pacific and Indian Ocean sectors of the ACC are consistent, with annual and semiannual amplitudes of 3.6 and 0.6 cm(H2O) ( 1.1 and 0.6 cm(H2O) with ECCO), the average over the full southern path peaks ( stronger ACC) in the southern winter, on days of year 197 and 97 for the annual and semiannual components, respectively; the Atlantic Ocean annual peak is 20 days earlier. An approximate conversion factor of 3.1 Sv ( Sv equivalent to 106 m(3) s(-1)) of barotropic transport variability per cm(H2O) of BP change is estimated. Wind stress data time series from the Quick Scatterometer ( QuikSCAT), averaged monthly, zonally, and over the latitude band 40 degrees - 65 degrees S, are also constructed and subsampled at the same months as with the GRACE data. The annual and semiannual harmonics of the wind stress peak on days 198 and 82, respectively. A decreasing trend over the 3 yr is observed in the three data types.
Keywords: annular mode, bottom pressure measurements, climate experiment, drake passage, earth, global ocean circulation, sea-level, surface, time-variable gravity, wind
ECCO Products Used: ECCO-KFS
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Johnson, E S; Bonjean, F; Lagerloef, G S E; Gunn, J T; Mitchum, G T (2007). Validation and error analysis of OSCAR sea surface currents, Journal of Atmospheric and Oceanic Technology, 4 (24), 688-701, 10.1175/jtech1971.1.
Title: Validation and error analysis of OSCAR sea surface currents
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Johnson, E S; Bonjean, F; Lagerloef, G S E; Gunn, J T; Mitchum, G T
Year: 2007
Formatted Citation: Johnson, E. S., F. Bonjean, G. S. E. Lagerloef, J. T. Gunn, and G. T. Mitchum, 2007: Validation and error analysis of OSCAR sea surface currents. Journal of Atmospheric and Oceanic Technology, 24(4), 688-701, doi:10.1175/jtech1971.1
Abstract: Comparisons of OSCAR satellite- derived sea surface currents with in situ data from moored current meters, drifters, and shipboard current profilers indicate that OSCAR presently provides accurate time means of zonal and meridional currents, and in the near- equatorial region reasonably accurate time variability ( correlation = 0.5 - 0.8) of zonal currents at periods as short as 40 days and meridional wavelengths as short as 8. At latitudes higher than 10 the zonal current correlation remains respectable, but OSCAR amplitudes diminish unrealistically. Variability of meridional currents is poorly reproduced, with severely diminished amplitudes and reduced correlations relative to those for zonal velocity on the equator. OSCAR's RMS differences from drifter velocities are very similar to those experienced by the ECCO ( Estimating the Circulation and Climate of the Ocean) data- assimilating models, but OSCAR generally provides a larger ocean- correlated signal, which enhances its ratio of estimated signal over noise. Several opportunities exist for modest improvements in OSCAR fidelity even with presently available datasets.
Keywords: altimetry, equatorial pacific, in-situ, model, ocean circulation, topex/poseidon, velocity
ECCO Products Used: ECCO-KFS;ECCO-V1
URL:
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Fenoglio-Marc, L; Kusche, J; Becker, M; Fukumori, I (2007). Comment on "On the steric and mass-induced contributions to the annual sea level variations in the Mediterranean Sea’’ by David Garcia et al., Journal of Geophysical Research-Oceans, C12 (112), 10.1029/2007jc004196.
Title: Comment on "On the steric and mass-induced contributions to the annual sea level variations in the Mediterranean Sea’’ by David Garcia et al.
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Fenoglio-Marc, L; Kusche, J; Becker, M; Fukumori, I
Year: 2007
Formatted Citation: Fenoglio-Marc, L., J. Kusche, M. Becker, and I. Fukumori, 2007: Comment on "On the steric and mass-induced contributions to the annual sea level variations in the Mediterranean Sea'' by David Garcia et al. J. Geophys. Res. Ocean., 112(C12), doi:10.1029/2007jc004196
Abstract:
Keywords: grace, model, temperature, time-variable gravity, water
ECCO Products Used: ECCO-KFS
URL:
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Schrama, E. J.O.; Visser, P. N.A.M. (2007). Accuracy assessment of the monthly GRACE geoids based upon a simulation, Journal of Geodesy, 1 (81), 67-80, 10.1007/s00190-006-0085-1.
Title: Accuracy assessment of the monthly GRACE geoids based upon a simulation
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Schrama, E. J.O.; Visser, P. N.A.M.
Year: 2007
Formatted Citation: Schrama, E. J., and P. N. Visser, 2007: Accuracy assessment of the monthly GRACE geoids based upon a simulation. Journal of Geodesy, 81(1), 67-80, doi:10.1007/s00190-006-0085-1
Abstract: The purpose of this paper is to demonstrate the effect of geophysical background model errors that affects temporal gravity solutions provided by the Gravity Recovery And Climate Experiment (GRACE). Initial performance estimates by Dickey et al. (1997) suggested a formal geoid RMS error better than 0.1 mm up to spherical harmonic degree 5. Now that the GRACE gravity models and data are available, it is evident that these original expectations were too optimistic. Our hypothesis is that this is partially explained by errors in geophysical background models that need to be applied in the GRACE data reduction, and that this effect was not considered by Dickey et al. (1997). We discuss the results of a closed-loop simulation, where satellite trajectory prediction software is used for the generation of GRACE range-rate data and GRACE orbit solutions with the help of the Global Positioning System (GPS). During the recovery step in our closed-loop simulation, we show that simulated nuisance signals (based on tide and air pressure model differences) map to a 0.7 mm geoid effect for periods longer than 3 months and to less than 0.4 mm for periods shorter than 3 months. The long-period geoid hydrology signal is at a level of 4.5 mm, while the short-period hydrology is at 0.25 mm. The long-period ocean bottom pressure (OBP) signal maps at 0.8 mm and for short periods it is 0.4 mm. We conclude that short-period effects are difficult to observe by GRACE and that long-period effects, like hydrology, are easier to recover than OBP variations.
Keywords: Air pressure, GPS, GRACE, Hydrology, Ocean bottom pressure, Temporal gravity, Tides
ECCO Products Used: ECCO-KFS
URL:
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Menemenlis, Dimitris; Fukumori, I; Lee, T (2007). Atlantic to Mediterranean sea level difference driven by winds near Gibraltar strait, Journal of Physical Oceanography, 2 (37), 359-376, 10.1175/Jpo3015.1.
Title: Atlantic to Mediterranean sea level difference driven by winds near Gibraltar strait
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Menemenlis, Dimitris; Fukumori, I; Lee, T
Year: 2007
Formatted Citation: Menemenlis, D., I. Fukumori, and T. Lee, 2007: Atlantic to Mediterranean sea level difference driven by winds near Gibraltar strait. Journal of Physical Oceanography, 37(2), 359-376, doi:10.1175/Jpo3015.1
Abstract: Observations and numerical simulations show that winds near Gibraltar Strait cause an Atlantic Ocean to Mediterranean Sea sea level difference of 20 cm peak to peak with a 3-cm standard deviation for periods of days to years. Theoretical arguments and numerical experiments establish that this wind-driven sea level difference is caused in part by storm surges due to alongshore winds near the North African coastline on the Atlantic side of Gibraltar. The fraction of the Moroccan coastal current offshore of the 284-m isobath is deflected across Gibraltar Strait, west of Camarinal Sill, resulting in a geostrophic surface pressure gradient that contributes to a sea level difference at the stationary limit. The sea level difference is also caused in part by the along-strait wind setup, with a contribution proportional to the along- strait wind stress and to the length of Gibraltar Strait and adjoining regions and inversely proportional to its depth. In the 20 - 360-day band, average transfer coefficients between the Atlantic - Alboran sea level difference and surface wind stress at 36 degrees N, 6.5 degrees W, estimated from barometrically corrected Ocean Topography Experiment ( TOPEX)/Poseidon data and NCEP - NCAR reanalysis data, are 0.10 +/- 0.04 m Pa(-1) with 1 +/- 5-day lag and 0.19 +/- 0.08 m Pa(-1) with 5 +/- 4-day lag for the zonal and meridional wind stresses, respectively. This transfer function is consistent with equivalent estimates derived from a 1992 - 2003 high-resolution barotropic simulation forced by the NCEP - NCAR wind stress. The barotropic simulation explains 29% of the observed Atlantic - Alboran sea level difference in the 20 - 360-day band. In turn, the Alboran and Mediterranean mean sea level time series are highly correlated, rho = 0.7 in the observations and rho = 0.8 in the barotropic simulation, hence providing a pathway for winds near Gibraltar Strait to affect the mean sea level of the entire Mediterranean.
Keywords: altimetry, atmospheric-pressure, circulation, exchange, flows, fluctuations, model, ocean, topography, variability
ECCO Products Used: ECCO-KFS
URL:
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Nastula, J.; Kolaczek, B. (2007). Spectral Characteristic of Polar Motion in the 2005-2006 and 1999-2000 Winters Seasons, Artificial Satellites, 1 (42), 1-7, 10.2478/v10018-007-0013-5.
Title: Spectral Characteristic of Polar Motion in the 2005-2006 and 1999-2000 Winters Seasons
Type: Journal Article
Publication: Artificial Satellites
Author(s): Nastula, J.; Kolaczek, B.
Year: 2007
Formatted Citation: Nastula, J., and B. Kolaczek, 2007: Spectral Characteristic of Polar Motion in the 2005-2006 and 1999-2000 Winters Seasons. Artificial Satellites, 42(1), 1-7, doi:10.2478/v10018-007-0013-5
Abstract:
Keywords: 1, 10, 2006 and 1999-2000 winters, 2007, 2478, 42, doi, ificial satellites, motion in the 2005-, no, seasons, spectral characteristic of polar, v10018-007-0013-5, vol
ECCO Products Used: ECCO-KFS
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Fukumori, I; Menemenlis, Dimitris; Lee, T (2007). A near-uniform basin-wide sea level fluctuation of the Mediterranean Sea, Journal of Physical Oceanography, 2 (37), 338-358, 10.1175/Jpo3016.1.
Title: A near-uniform basin-wide sea level fluctuation of the Mediterranean Sea
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Fukumori, I; Menemenlis, Dimitris; Lee, T
Year: 2007
Formatted Citation: Fukumori, I., D. Menemenlis, and T. Lee, 2007: A near-uniform basin-wide sea level fluctuation of the Mediterranean Sea. Journal of Physical Oceanography, 37(2), 338-358, doi:10.1175/Jpo3016.1
Abstract: A new basin-wide oscillation of the Mediterranean Sea is identified and analyzed using sea level observations from the Ocean Topography Experiment ( TOPEX)/Poseidon satellite altimeter and a numerical ocean circulation model. More than 50% of the large-scale, nontidal, and non-pressure-driven variance of sea level can be attributed to this oscillation, which is nearly uniform in phase and amplitude across the entire basin. The oscillation has periods ranging from 10 days to several years and has a magnitude as large as 10 cm. The model suggests that the fluctuations are driven by winds at the Strait of Gibraltar and its neighboring region, including the Alboran Sea and a part of the Atlantic Ocean immediately to the west of the strait. Winds in this region force a net mass flux through the Strait of Gibraltar to which the Mediterranean Sea adjusts almost uniformly across its entire basin with depth-independent pressure perturbations. The wind-driven response can be explained in part by wind setup; a near-stationary balance is established between the along-strait wind in this forcing region and the sea level difference between the Mediterranean Sea and the Atlantic Ocean. The amplitude of this basin-wide wind-driven sea level fluctuation is inversely proportional to the setup region's depth but is insensitive to its width including that of Gibraltar Strait. The wind-driven fluctuation is coherent with atmospheric pressure over the basin and contributes to the apparent deviation of the Mediterranean Sea from an inverse barometer response.
Keywords: atlantic, atmospheric-pressure, black-sea, exchange, flow-through, general-circulation, model, pacific-ocean, strait-of-gibraltar, variability
ECCO Products Used: Adjoint;ECCO-KFS
URL:
Other URLs:
Bingham, R. J.; Hughes, C. W. (2006). Observing seasonal bottom pressure variability in the North Pacific with GRACE, Geophysical Research Letters, 8 (33), L08607, 10.1029/2005GL025489.
Title: Observing seasonal bottom pressure variability in the North Pacific with GRACE
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Bingham, R. J.; Hughes, C. W.
Year: 2006
Formatted Citation: Bingham, R. J., and C. W. Hughes, 2006: Observing seasonal bottom pressure variability in the North Pacific with GRACE. Geophys. Res. Lett., 33(8), L08607, doi:10.1029/2005GL025489
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Matsumoto, K; Sato, T; Fujimoto, H; Tamura, Y; Nishino, M; Hino, R; Higashi, T; Kanazawa, T (2006). Ocean bottom pressure observation off Sanriku and comparison with ocean tide models, altimetry, and barotropic signals from ocean models, Geophysical Research Letters, 16 (33), 10.1029/2006gl026706.
Title: Ocean bottom pressure observation off Sanriku and comparison with ocean tide models, altimetry, and barotropic signals from ocean models
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Matsumoto, K; Sato, T; Fujimoto, H; Tamura, Y; Nishino, M; Hino, R; Higashi, T; Kanazawa, T
Year: 2006
Formatted Citation: Matsumoto, K., T. Sato, H. Fujimoto, Y. Tamura, M. Nishino, R. Hino, T. Higashi, and T. Kanazawa, 2006: Ocean bottom pressure observation off Sanriku and comparison with ocean tide models, altimetry, and barotropic signals from ocean models. Geophys. Res. Lett., 33(16), doi:10.1029/2006gl026706
Abstract: We discuss tidal and non-tidal signals which are obtained from ocean bottom pressure (OBP) measurements at two sites off Sanriku, Japan. Comparison between the observed tidal component and five ocean tide models shows that recent models have accuracy better than 1.3 cm in terms of root sum square of vector differences for eight principal constituents. The empirical estimates of non-tidal signal from TOPEX/POSEIDON (T/P) and JASON-1 deviate from barotropic signals observed by OBP recorders, which can be attributed to baroclinic component in the altimeter data. We also compared the non-tidal barotropic signal derived from the observation with those from ECCO model (wind-driven) and Kyushu University model (pressure-driven). The comparison indicates that the pressure-driven model increases explained variance and it is suggested to combine the wind-driven model and the pressure-driven model in order to describe non-tidal ocean mass variability in particular at period shorter than 30 days.
Keywords:
ECCO Products Used: ECCO-KFS
URL:
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Takiguchi, Hiroshi; Fukuda, Yoichi; Otsubo, Toshimichi (2006). Mass-redistribution-induced crustal deformation of global satellite laser ranging stations due to non-tidal ocean and land water circulation, Earth, Planets and Space, 2 (58), E13-E16, 10.1186/BF03353365.
Title: Mass-redistribution-induced crustal deformation of global satellite laser ranging stations due to non-tidal ocean and land water circulation
Type: Journal Article
Publication: Earth, Planets and Space
Author(s): Takiguchi, Hiroshi; Fukuda, Yoichi; Otsubo, Toshimichi
Year: 2006
Formatted Citation: Takiguchi, H., Y. Fukuda, and T. Otsubo, 2006: Mass-redistribution-induced crustal deformation of global satellite laser ranging stations due to non-tidal ocean and land water circulation. Earth, Planets and Space, 58(2), E13-E16, doi:10.1186/BF03353365
Abstract: The effect of the non-tidal ocean load (NTOL) and the continental water load (CWL) on crustal deformation are calculated for global satellite laser ranging (SLR) stations and on 4 degrees x 4 degrees grids (only over the land). For the regions most severely affected, the peak-to-peak displacements due to the NTOL are found to be as large as 3 mm for the horizontal components and 10 mm for the vertical component. The peak-to-peak displacements due to the CWL reach 3 mm for the horizontal components and 15 mm for the vertical component. We apply the time series of NTOL and CWL to precise SLR analysis. The LAGEOS orbit analysis reveals that the Estimating the Circulation and Climate of the Ocean (ECCO) model makes the root mean square (RMS) of the range residual 0.2% smaller, and that the CWL makes it 0.8% smaller, compared with the case where loading displacement is neglected. On the other hand, with the NTOL derived from Topex/Poseidon altimetry data, the SLR orbit fit is not improved.
Keywords: ECCO, Satellite laser ranging, Topex/Poseidon, continental water load, crustal deformation, non-tidal ocean load
ECCO Products Used: ECCO-KFS
URL:
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Spiridonov, E. A.; Tsurkis, I. Ya. (2006). Modeling of the Earth’s pole motion from data on the atmospheric and oceanic angular momenta over 1980-2002, Izvestiya, Physics of the Solid Earth, 2 (42), 149-155, 10.1134/S1069351306020066.
Title: Modeling of the Earth’s pole motion from data on the atmospheric and oceanic angular momenta over 1980-2002
Type: Journal Article
Publication: Izvestiya, Physics of the Solid Earth
Author(s): Spiridonov, E. A.; Tsurkis, I. Ya.
Year: 2006
Formatted Citation: Spiridonov, E. A., and I. Y. Tsurkis, 2006: Modeling of the Earth's pole motion from data on the atmospheric and oceanic angular momenta over 1980-2002. Izvestiya, Physics of the Solid Earth, 42(2), 149-155, doi:10.1134/S1069351306020066
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Fukumori, Ichiro (2006). What is data assimilation really solving, and how is the calculation actually done?, Ocean Weather Forecasting: An Integrated View of Oceanography, 317-342, 10.1007/1-4020-4028-8_11.
Title: What is data assimilation really solving, and how is the calculation actually done?
Type: Book Section
Publication: Ocean Weather Forecasting: An Integrated View of Oceanography
Author(s): Fukumori, Ichiro
Year: 2006
Formatted Citation: Fukumori, I., 2006: What is data assimilation really solving, and how is the calculation actually done?. Ocean Weather Forecasting: An Integrated View of Oceanography, E. Chassignet, and J. Verron, Eds., Springer Netherlands, 317-342, doi:10.1007/1-4020-4028-8_11
Abstract: Data assimilation is reviewed in the context of an inverse problem. The mathematical nature of the problem is examined and some of its common solutions are described, clarifying some of the implicit assumptions that underlie both problem and solution. For instance, Kalman filtering and Rauch-Tung-Striebel smoothing can be identified as recursive least-squares inversions of the assimilation problem but of different parts of the problem. The temporal evolution of a filtered solution is not physically consistent, but that of a smoothed solution is. Understanding these characteristics is essential in effectively assimilating observations as well as in utilizing and further improving the assimilated solution. Practical steps in implementing a filtering and smoothing algorithm are illustrated by examples from the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). © 2006 Springer.
Keywords: Data assimilation, ECCO, Kalman filter, consistency, smoother
ECCO Products Used: ECCO-KFS
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Kim, S B; Fukumori, I; Lee, T (2006). The closure of the ocean mixed layer temperature budget using level-coordinate model fields, Journal of Atmospheric and Oceanic Technology, 6 (23), 840-853, 10.1175/Jtech1883.1.
Title: The closure of the ocean mixed layer temperature budget using level-coordinate model fields
Type: Journal Article
Publication: Journal of Atmospheric and Oceanic Technology
Author(s): Kim, S B; Fukumori, I; Lee, T
Year: 2006
Formatted Citation: Kim, S. B., I. Fukumori, and T. Lee, 2006: The closure of the ocean mixed layer temperature budget using level-coordinate model fields. Journal of Atmospheric and Oceanic Technology, 23(6), 840-853, doi:10.1175/Jtech1883.1
Abstract: Entrainment is an important element of the mixed layer mass, heat, and temperature budgets. Conventional procedures to estimate entrainment heat advection often do not permit the closure of heat and temperature budgets because of inaccuracies in its formulation. In this study a rigorous approach to evaluate the effect of entrainment using the output of a general circulation model ( GCM) that does not have an explicit prognostic mixed layer model is described. The integral elements of the evaluation are 1) the rigorous estimates of the temperature difference between mixed layer water and entrained water at each horizontal grid point, 2) the formulation of the temperature difference such that the budget closes over a volume greater than one horizontal grid point, and 3) the apparent warming of the mixed layer during the mixed layer shoaling to account for the weak vertical temperature gradient within the mixed layer. This evaluation of entrainment heat advection is compared with the estimates by other commonly used ad hoc formulations by applying them in three regions: the north-central Pacific, the Kuroshio Extension, and the Nino-3 areas in the tropical Pacific. In all three areas the imbalance in the mixed layer temperature budget by the ad hoc estimates is significant, reaching a maximum of about 4 K yr(-1).
Keywords: cycle, el-nino, equatorial pacific, heat-balance, kuroshio extension region, sea-surface temperature, sst, tropical pacific, variability
ECCO Products Used: ECCO-KFS
URL:
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Benjamin, David; Wahr, John; Ray, Richard D.; Egbert, Gary D.; Desai, Shailen D. (2006). Constraints on mantle anelasticity from geodetic observations, and implications for the J 2 anomaly, Geophysical Journal International, 1 (165), 3-16, 10.1111/j.1365-246X.2006.02915.x.
Title: Constraints on mantle anelasticity from geodetic observations, and implications for the J 2 anomaly
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Benjamin, David; Wahr, John; Ray, Richard D.; Egbert, Gary D.; Desai, Shailen D.
Year: 2006
Formatted Citation: Benjamin, D., J. Wahr, R. D. Ray, G. D. Egbert, and S. D. Desai, 2006: Constraints on mantle anelasticity from geodetic observations, and implications for the J 2 anomaly. Geophysical Journal International, 165(1), 3-16, doi:10.1111/j.1365-246X.2006.02915.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Wu, X P; Heflin, M B; Ivins, E R; Fukumori, I (2006). Seasonal and interannual global surface mass variations from multisatellite geodetic data, Journal of Geophysical Research-Solid Earth, B9 (111), B09401, 10.1029/2005jb004100.
Title: Seasonal and interannual global surface mass variations from multisatellite geodetic data
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Wu, X P; Heflin, M B; Ivins, E R; Fukumori, I
Year: 2006
Formatted Citation: Wu, X. P., M. B. Heflin, E. R. Ivins, and I. Fukumori, 2006: Seasonal and interannual global surface mass variations from multisatellite geodetic data. Journal of Geophysical Research-Solid Earth, 111(B9), B09401, doi:10.1029/2005jb004100
Abstract: [ 1] Monthly global surface mass distribution changes are estimated in the spherical harmonic domain with a complete spectrum up to degree and order 50. The estimates are derived by inverting GPS displacement series measured at roughly 450 continuously tracking sites and ocean bottom pressure (OBP) estimates of a data assimilated ocean circulation model from 1993 to 2004. The inversion uses a hybrid estimator after singular value decomposition of the normalized measurement equations with reduced reliance on a priori spectral information. The results are then compared and combined with Gravity Recovery and Climate Experiment ( GRACE) gravity data to provide enhanced spectral and geographic coverage. High fidelity degree-1 surface mass variation coefficients are recovered, corresponding to equivalent geocenter motion with better than 0.5 mm annual amplitude precisions in all three components. A clear annual surface mass cycle occurs in both GPS/OBP- and GRACE-derived results. There is very good agreement among the low-degree spherical harmonic coefficients and in global geographic pattern but with significant regional differences in amplitudes. Annual variations of average mass over the global oceans, Antarctica, and Greenland are then derived. Total surface mass over both Antarctica and Greenland peak in their respective summers due to increased atmospheric mass. Large interannual variations have also been found involving several continents in the 11-year GPS/OBP solution. The patterns of variation suggest that the recent satellite laser ranging (SLR) observation of a reversal in trend of the Earth's oblateness may be largely an interannual surface mass cycle with considerable contribution from the northern continents.
Keywords: deformation, earth, field, geocenter variations, gps data, motion, sea-level, system, time-variable gravity, variability
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Han, Shin-Chan; Shum, C. K.; Jekeli, Christopher; Kuo, Chung-Yen; Wilson, Clark; Seo, Ki-Weon (2005). Non-isotropic filtering of GRACE temporal gravity for geophysical signal enhancement, Geophysical Journal International, 1 (163), 18-25, 10.1111/j.1365-246X.2005.02756.x.
Title: Non-isotropic filtering of GRACE temporal gravity for geophysical signal enhancement
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Han, Shin-Chan; Shum, C. K.; Jekeli, Christopher; Kuo, Chung-Yen; Wilson, Clark; Seo, Ki-Weon
Year: 2005
Formatted Citation: Han, S., C. K. Shum, C. Jekeli, C. Kuo, C. Wilson, and K. Seo, 2005: Non-isotropic filtering of GRACE temporal gravity for geophysical signal enhancement. Geophysical Journal International, 163(1), 18-25, doi:10.1111/j.1365-246X.2005.02756.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chen, Jianli (2005). Global mass balance and the length-of-day variation, Journal of Geophysical Research, B8 (110), B08404, 10.1029/2004JB003474.
Title: Global mass balance and the length-of-day variation
Type: Journal Article
Publication: Journal of Geophysical Research
Author(s): Chen, Jianli
Year: 2005
Formatted Citation: Chen, J., 2005: Global mass balance and the length-of-day variation. Journal of Geophysical Research, 110(B8), B08404, doi:10.1029/2004JB003474
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Gross, R S; Fukumori, I; Menemenlis, Dimitris (2005). Atmospheric and oceanic excitation of decadal-scale Earth orientation variations, Journal of Geophysical Research-Solid Earth, B9 (110), B09405, 10.1029/2004jb003565.
Title: Atmospheric and oceanic excitation of decadal-scale Earth orientation variations
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Gross, R S; Fukumori, I; Menemenlis, Dimitris
Year: 2005
Formatted Citation: Gross, R. S., I. Fukumori, and D. Menemenlis, 2005: Atmospheric and oceanic excitation of decadal-scale Earth orientation variations. Journal of Geophysical Research-Solid Earth, 110(B9), B09405, doi:10.1029/2004jb003565
Abstract: The contribution of atmospheric wind and surface pressure and oceanic current and bottom pressure variations during 1949-2002 to exciting changes in the Earth's orientation on decadal timescales is investigated using an atmospheric angular momentum series computed from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis project and an oceanic angular momentum series computed from a near-global ocean model that was forced by surface fluxes from the NCEP/NCAR reanalysis project. Not surprisingly, since decadal-scale variations in the length of day are caused mainly by interactions between the mantle and core, the effect of the atmosphere and oceans is found to be only about 14% of that observed. More surprisingly, it is found that the effect of atmospheric and oceanic processes on decadal-scale changes in polar motion is also only about 20% (x component) and 38% (y component) of that observed. Therefore redistribution of mass within the atmosphere and oceans does not appear to be the main cause of the Markowitz wobble. It is also found that on timescales between 10 days and 4 years the atmospheric and oceanic angular momentum series used here have very little skill in explaining Earth orientation variations before the mid to late 1970s. This is attributed to errors in both the Earth orientation observations prior to 1976 when measurements from the accurate space-geodetic techniques became available and to errors in the modeled atmospheric fields prior to 1979 when the satellite era of global weather observing systems began.
Keywords: angular-momentum, core, fluctuations, ice, model, polar motion, reanalysis, representation, rotation, tides
ECCO Products Used: ECCO-KFS
URL:
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Menemenlis, Dimitris; Fukumori, I; Lee, T (2005). Using Green’s functions to calibrate an ocean general circulation model, Monthly Weather Review, 5 (133), 1224-1240, 10.1175/Mwr2912.1.
Title: Using Green’s functions to calibrate an ocean general circulation model
Type: Journal Article
Publication: Monthly Weather Review
Author(s): Menemenlis, Dimitris; Fukumori, I; Lee, T
Year: 2005
Formatted Citation: Menemenlis, D., I. Fukumori, and T. Lee, 2005: Using Green's functions to calibrate an ocean general circulation model. Monthly Weather Review, 133(5), 1224-1240, doi:10.1175/Mwr2912.1
Abstract: Green's functions provide a simple yet effective method to test and to calibrate general circulation model (GCM) parameterizations, to study and to quantify model and data errors, to correct model biases and trends, and to blend estimates from different solutions and data products. The method is applied to an ocean GCM, resulting in substantial improvements of the solution relative to observations when compared to prior estimates: overall model bias and drift are reduced and there is a 10%-30% increase in explained variance. Within the context of this optimization, the following new estimates for commonly used ocean GCM parameters are obtained. Background vertical diffusivity is (15.1 +/- 0.1) X 10(-6) m(2) s(-2). Background vertical viscosity is (18 +/- 3) x 10(-6) m(2) s(-2). The critical bulk Richardson number, which sets boundary layer depth, is Ri(c), = 0.354 +/- 0.004. The threshold gradient Richardson number for shear instability vertical mixing is Rio = 0.699 +/- 0.008. The estimated isopycnal diffusivity coefficient ranges from 550 to 1350 m(2) s(-2), with the largest values occurring at depth in regions of increased mesoscale eddy activity. Surprisingly, the estimated isopycnal diffusivity exhibits a 5%-35% decrease near the surface. Improved estimates of initial and boundary conditions are also obtained. The above estimates are the backbone of a quasi-operational, global-ocean circulation analysis system.
Keywords: boundary, climate, data assimilation, fluxes, heat, pacific-ocean, satellite altimetry, transports, volume
ECCO Products Used: ECCO-KFS
URL:
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Thomas, M.; Dobslaw, H.; Stuck, J.; Seitz, F. (2005). The ocean’s contribution to polar motion excitation - as many solutions as numerical models?, Forcing of polar motion in the Chandler frequency band: A contribution to understanding interannual climate variations, Cahiers du Centre Européen de Géodynamique et de Séismologie, 143-148.
Title: The ocean’s contribution to polar motion excitation - as many solutions as numerical models?
Type: Book Section
Publication: Forcing of polar motion in the Chandler frequency band: A contribution to understanding interannual climate variations, Cahiers du Centre Européen de Géodynamique et de Séismologie
Author(s): Thomas, M.; Dobslaw, H.; Stuck, J.; Seitz, F.
Year: 2005
Formatted Citation: Thomas, M., H. Dobslaw, J. Stuck, and F. Seitz, 2005: The ocean's contribution to polar motion excitation - as many solutions as numerical models?. Forcing of polar motion in the Chandler frequency band: A contribution to understanding interannual climate variations, Cahiers du Centre Européen de Géodynamique et de Séismologie, European Center for Geodynamics and Seismology (ECGS), 143-148, https://mediatum.ub.tum.de/1367787
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Davis, R E (2005). Intermediate-depth circulation of the Indian and South Pacific Oceans measured by autonomous floats, Journal of Physical Oceanography, 5 (35), 683-707, 10.1175/jpo2702.1.
Title: Intermediate-depth circulation of the Indian and South Pacific Oceans measured by autonomous floats
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Davis, R E
Year: 2005
Formatted Citation: Davis, R. E., 2005: Intermediate-depth circulation of the Indian and South Pacific Oceans measured by autonomous floats. Journal of Physical Oceanography, 35(5), 683-707, doi:10.1175/jpo2702.1
Abstract: As part of the World Ocean Circulation Experiment, 306 autonomous floats were deployed in the tropical and South Pacific Ocean and 228 were deployed in the Indian Ocean to observe the basinwide circulation near 900-m depth. Mean velocities, seasonal variability, and lateral eddy diffusivity from the resultant 2583 float-years of data are presented. Area averages, local function fits, and a novel application of objective mapping are used to estimate the mean circulation. Patterns of mean circulation resemble those at the surface in both basins. Well-developed subtropical gyres, twice as strong in the Indian Ocean as in the Pacific, feed western boundary currents. Tropical gyres are separated by eastward flow along the equator in both hemispheres of both basins, although the Indian subcontinent splits the north Indian tropical gyre. The Antarctic Circumpolar Current (ACC) and west wind drifts are prominent in both basins, generally tending slightly southward but deviating to the north behind the Del Cano, Kerguelen, and Campbell Plateaus and, of course, South America. Remarkably, the eastern boundaries of the southern subtropical gyres in all three basins apparently occur in the ocean interior, away from land. The Indian Ocean's subtropical gyre, and perhaps part of the South Atlantic's, reaches east to a retroflection just upstream of the Campbell Plateau south of New Zealand. Seasonal variability at 900 m is focused around the equator with weaker variability found near certain bathymetric features. There is a remarkable agreement between the observed seasonable variability and that predicted by the Jet Propulsion Laboratory (JPL)-Estimating the Circulation and Climate of the Ocean (ECCO) data-assimilating numerical model. Aside from seasonal effects, eddy variability is greatest along the equator, in tropical and subtropical western basins, and along the ACC. Integrals of velocity across regional passages (Tasman Sea, Mozambique Channel) provide useful reference for hydrographic analyses of transport. Across whole ocean basins, however, the uncertainty associated with the appropriate continuity relation for horizontal flow (e.g., geostrophy vs nondivergence) is comparable to the mean flow.
Keywords: alace, flow patterns, north-atlantic, topography, total geostrophic circulation, tracers, trajectories, transports, variability, velocity
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Holme, R.; de Viron, O. (2005). Geomagnetic jerks and a high-resolution length-of-day profile for core studies, Geophysical Journal International, 2 (160), 435-439, 10.1111/j.1365-246X.2004.02510.x.
Title: Geomagnetic jerks and a high-resolution length-of-day profile for core studies
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Holme, R.; de Viron, O.
Year: 2005
Formatted Citation: Holme, R., and O. de Viron, 2005: Geomagnetic jerks and a high-resolution length-of-day profile for core studies. Geophysical Journal International, 160(2), 435-439, doi:10.1111/j.1365-246X.2004.02510.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chen, J. L.; Wilson, C. R. (2005). Hydrological excitations of polar motion, 1993-2002, Geophysical Journal International, 3 (160), 833-839, 10.1111/j.1365-246X.2005.02522.x.
Title: Hydrological excitations of polar motion, 1993-2002
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Chen, J. L.; Wilson, C. R.
Year: 2005
Formatted Citation: Chen, J. L., and C. R. Wilson, 2005: Hydrological excitations of polar motion, 1993-2002. Geophysical Journal International, 160(3), 833-839, doi:10.1111/j.1365-246X.2005.02522.x
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Worcester, Peter F.; Cornuelle, Bruce D.; Dzieciuch, Matthew A.; Munk, Walter H. (2005). North Pacific Acoustic Laboratory : Deep Water Acoustic Propagation in the Philippine Sea, Munk, Walter H, 1-11.
Title: North Pacific Acoustic Laboratory : Deep Water Acoustic Propagation in the Philippine Sea
Type: Report
Publication: Munk, Walter H
Author(s): Worcester, Peter F.; Cornuelle, Bruce D.; Dzieciuch, Matthew A.; Munk, Walter H.
Year: 2005
Formatted Citation: Worcester, P. F., B. D. Cornuelle, M. A. Dzieciuch, and W. H. Munk, 2005: North Pacific Acoustic Laboratory : Deep Water Acoustic Propagation in the Philippine Sea. Munk, Walter H, La Jolla, CA, 1-11 pp.
Abstract: The North Pacific Acoustic Laboratory (NPAL) program is intended to improve our understanding of (i) the basic physics of low-frequency, broadband propagation in deep water, including the effects of oceanographic variability on signal stability and coherence, (ii) the structure of the ambient noise field in deep water at low frequencies, and (iii) the extent to which acoustic methods, together with other measurements and coupled with ocean modeling, can yield estimates of the time-evolving ocean state useful for acoustic predictions. The goal is to determine the fundamental limits to signal processing in deep water imposed by ocean processes, enabling advanced signal processing techniques to capitalize on the three-dimensional character of the sound and noise fields.
Keywords: acoust, coherence, deep water acoustic propagation
ECCO Products Used: ECCO-KFS
Other URLs: https://apps.dtic.mil/dtic/tr/fulltext/u2/a531825.pdf
Seo, K.-W.; Wilson, C. R. (2005). Simulated estimation of hydrological loads from GRACE, Journal of Geodesy, 7-8 (78), 442-456, 10.1007/s00190-004-0410-5.
Title: Simulated estimation of hydrological loads from GRACE
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Seo, K.-W.; Wilson, C. R.
Year: 2005
Formatted Citation: Seo, K., and C. R. Wilson, 2005: Simulated estimation of hydrological loads from GRACE. Journal of Geodesy, 78(7-8), 442-456, doi:10.1007/s00190-004-0410-5
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Zhou, Y H; Chen, J L; Liao, X H; Wilson, C R (2005). Oceanic excitations on polar motion: a cross comparison among models, Geophysical Journal International, 2 (162), 390-398, 10.1111/j.1365-246X.2005.02694.x.
Title: Oceanic excitations on polar motion: a cross comparison among models
Type: Journal Article
Publication: Geophysical Journal International
Author(s): Zhou, Y H; Chen, J L; Liao, X H; Wilson, C R
Year: 2005
Formatted Citation: Zhou, Y. H., J. L. Chen, X. H. Liao, and C. R. Wilson, 2005: Oceanic excitations on polar motion: a cross comparison among models. Geophysical Journal International, 162(2), 390-398, doi:10.1111/j.1365-246X.2005.02694.x
Abstract: Recent studies based on various ocean general circulation models (OGCMs) demonstrate that the oceans are a major contributor to polar motion excitations. In this paper, we analyse and compare observed non-atmospheric polar motion excitations with oceanic angular momentum (OAM) variations determined from four OGCMs, which include the parallel ocean climate model (POCM), a barotropic ocean model (BOM), the Estimating the Circulation and Climate of the Ocean (ECCO) non-data-assimilating model (ECCO-NDA) and the ECCO data-assimilating model (ECCO-DA). The data to be analysed span a 5-yr overlapped period from 1993 to 1997. At annual timescale, considerable discrepancies exist between POCM and the other three models, which result mainly from differences in annual components of the forcing wind fields. At semi-annual timescale, however, POCM shows better phase agreement with observed non-atmospheric polar motion excitation than the other three ocean models. At intraseasonal timescales, ECCO-DA yields better agreement with observations, and reduces the variance of non-atmospheric excitations by similar to 60 per cent, 10-20 per cent more than those explained by the other three models. However, at the very short periods of 4-20 days, the BOM estimates could explain about half of the observed variance, twice as much as that by ECCO-NDA, and also shows considerably better correlation with observations. Due to different modelling schemes and methods, significant discrepancies could arise with respect to the quality of modelling large-scale oceanic mass redistribution and current variation. A complete understanding of global oceanic contributions to polar motion excitation still remains a challenge.
Keywords: angular-momentum, atmosphere, circulation model, earths wobble, equations, excitation, momentum (OAM), ocean general circulation model (OGCM), oceanic angular, polar motion, pressure, rotation, sea-level, signals, variability
ECCO Products Used: ECCO-KFS
URL:
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Lee, Tong; Liu, Timothy W (2005). Effects of high-frequency wind sampling on simulated mixed layer depth and upper ocean temperature, Journal of Geophysical Research: Oceans, C5 (110), 10.1029/2004JC002746.
Title: Effects of high-frequency wind sampling on simulated mixed layer depth and upper ocean temperature
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Lee, Tong; Liu, Timothy W
Year: 2005
Formatted Citation: Lee, T., and T. W. Liu, 2005: Effects of high-frequency wind sampling on simulated mixed layer depth and upper ocean temperature. J. Geophys. Res. Ocean., 110(C5), doi:10.1029/2004JC002746
Abstract: Effects of high-frequency wind sampling on a near-global ocean model are studied by forcing the model with a 12 hourly averaged wind product and its 24 hourly subsamples in separate experiments. The differences in mixed layer depth and sea surface temperature resulting from these experiments are examined, and the underlying physical processes are investigated. The 24 hourly subsampling not only reduces the high-frequency variability of the wind but also affects the annual mean wind because of aliasing. While the former effect largely impacts mid- to high-latitude oceans, the latter primarily affects tropical and coastal oceans. At mid- to high-latitude regions the subsampled wind results in a shallower mixed layer and higher sea surface temperature because of reduced vertical mixing associated with weaker high-frequency wind. In tropical and coastal regions, however, the change in upper ocean structure due to the wind subsampling is primarily caused by the difference in advection resulting from aliased annual mean wind, which varies with the subsampling time. The results of the study indicate a need for more frequent sampling of satellite wind measurement and have implications for data assimilation in terms of identifying the nature of model errors.
Keywords: high-frequency wind, mixed layer, sea surface temperature
ECCO Products Used: ECCO-KFS
Other URLs:
Glazman, Roman E; Golubev, Yury N (2005). Variability of the ocean-induced magnetic field predicted at sea surface and at satellite altitudes, Journal of Geophysical Research: Oceans, C12 (110), 10.1029/2005JC002926.
Title: Variability of the ocean-induced magnetic field predicted at sea surface and at satellite altitudes
Type: Journal Article
Publication: Journal of Geophysical Research: Oceans
Author(s): Glazman, Roman E; Golubev, Yury N
Year: 2005
Formatted Citation: Glazman, R. E., and Y. N. Golubev, 2005: Variability of the ocean-induced magnetic field predicted at sea surface and at satellite altitudes. J. Geophys. Res. Ocean., 110(C12), doi:10.1029/2005JC002926
Abstract: Spatial and temporal variability of the magnetic field component induced by ocean circulation is investigated on the basis of a standard thin-shell approximation of electro- and magneto-static equations. Well-known difficulties of numerical solution of the governing equations are resolved by reducing the problem to an equation for the electric field potential, Φ, as opposed to a more conventional approach focused on the vertical jump, ψ, of the magnetic field potential across a combined ocean/marine-sediment-layer spherical shell. The present formulation permits using more realistic input data on ocean currents and ultimately yields much greater (by at least an order of magnitude) values of the magnetic field at sea surface than predicted in earlier studies. Such large values are comparable to, and in some cases exceed, magnetic field variations caused by lithospheric and ionospheric sources on monthly to interannual timescales. At the 400-km altitude (of CHAMP satellite), the field attains 6 nT. The model predictions show favorable comparisons with some in situ measurements as well as with Challenging Minisatellite Payload (CHAMP) satellite magnetometer data.
Keywords: 0619 Electromagnetic theory, 0689 Wave propagation, 1517 Magnetic anomalies: modeling and interpretati, 1545 Spatial variations: all harmonics and anomali, 4275 Remote sensing and electromagnetic processes, Earth's magnetic field, ocean induction, ocean remote sensing
ECCO Products Used: ECCO-KFS;ECCO2
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Žuvela-Aloise, Maja (2005). Modelling of the Indonesian Throughflow on glacial-interglacial time-scales.
Title: Modelling of the Indonesian Throughflow on glacial-interglacial time-scales
Type: Thesis
Publication:
Author(s): Žuvela-Aloise, Maja
Year: 2005
Formatted Citation: Žuvela-Aloise, M., 2005: Modelling of the Indonesian Throughflow on glacial-interglacial time-scales, December
Abstract: The Indonesian Throughflow transports warm and fresh Pacific waters into the Indian Ocean and is a major tropical pathway of the global thermohaline circulation. An important paleoclimatic question is to what extent lowered sea level at the Last Glacial Maximum effected the Indonesian Throughflow by restricting the gateways aperture. In this study, a regional dynamics of the Indonesian Throughflow are analysed for present- day and Last Glacial Maximum conditions. The focus of the study is on the impact of changes in Indonesian Gateways configuration on ocean circulation and distribution of marine organisms. A high resolution regional ocean model with seasonal forcing is used to simulate mean climatic circulation through the Indonesian Gateways. During the Last Glacial Maximum, both bathymetry and climate conditions were different. Relative importance of individual effects is investigated by separately testing the sensitivity of the ITF volume and heat transport to the sea level lowering and to the glacial climate conditions. The closure of the main passages is expected to reduce mean ITF transport during the glacial period. However, model results show that reduction in the glacial sea level of 120 m does not seem to be sufficient to severely block the flow within the Makassar Strait as the main passage of the Throughflow. An important impact of topographic changes is found in the vertical profile of the flow. Reduction in sill depth and absence of low buoyancy surface waters due to the exposure of shelf area lead to intensification of surface flow within Makassar Strait. Moreover, the seasonality of the surface flow is changed compared to the present-day. Both effects might have significant impact on the heat transport towards the Indian Ocean. A strong impact of individual passages on ITF profile and seasonal variability emphasis the role of Indonesian Gateways on modulating the water masses exchange between the Pacific and the Indian Ocean. However, the intensity of the Throughflow seems to be highly dependant on the boundary conditions. Glacial climate conditions lead to reduction in ITF transport which might be related to several factors out of scope of regional dynamics. Such factors could include glacial changes in wind stress over Pacific, changes in density gradient between Pacific and Indian Ocean or overall El- Niño conditions over the tropical Pacific. In addition, by calculating Lagrangian trajectories, main pathways, velocities of propagation and probabilities of exchange of marine biota between the Pacific and the Indian Ocean can be assessed. The developed patterns of distribution can be in the future compared with sedimentological evidence from the region.
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0;ECCO2
URL:
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Mechoso, Carlos R; Cazes-Boezio, Gabriel; Menemenlis, Dimitris (2005). Experimental ENSO predictions by the UCLA atmospheric GCM coupled to the MIT and POP Oceanic GCMs using the Earth System Modeling Framework (ESMF), Proceedings of the NASA Earth Science Technology Conference 2005, 1-5.
Title: Experimental ENSO predictions by the UCLA atmospheric GCM coupled to the MIT and POP Oceanic GCMs using the Earth System Modeling Framework (ESMF)
Type: Conference Proceedings
Publication: Proceedings of the NASA Earth Science Technology Conference 2005
Author(s): Mechoso, Carlos R; Cazes-Boezio, Gabriel; Menemenlis, Dimitris
Year: 2005
Formatted Citation: Mechoso, C. R., G. Cazes-Boezio, and D. Menemenlis, 2005: Experimental ENSO predictions by the UCLA atmospheric GCM coupled to the MIT and POP Oceanic GCMs using the Earth System Modeling Framework (ESMF). Proceedings of the NASA Earth Science Technology Conference 2005, College Park, MD, 1-5 pp. https://esto.nasa.gov/conferences/estc2005/papers/a7p1.pdf.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Chen, J.L.; Wilson, C.R.; Tapley, B.D. (2005). Interannual variability of low-degree gravitational change, 1980-2002, Journal of Geodesy, 9 (78), 535-543, 10.1007/s00190-004-0417-y.
Title: Interannual variability of low-degree gravitational change, 1980-2002
Type: Journal Article
Publication: Journal of Geodesy
Author(s): Chen, J.L.; Wilson, C.R.; Tapley, B.D.
Year: 2005
Formatted Citation: Chen, J., C. Wilson, and B. Tapley, 2005: Interannual variability of low-degree gravitational change, 1980-2002. Journal of Geodesy, 78(9), 535-543, doi:10.1007/s00190-004-0417-y
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Worcester, Peter F; Cornuelle, Bruce D; Dushaw, Brian D.; Dzieciuch, Matthew A; Howe, Bruce M; Menemenlis, Dimitris; Mercer, James A; Munk, Walter H; Spindel, Robert C; Stammer, Detlef; Zarnetske, Michael (2004). ACOUSTIC REMOTE SENSING OF LARGE-SCALE TEMPERATURE VARIABILITY IN THE NORTH PACIFIC OCEAN, Gayana (Concepción), 2 (68), 576-577, 10.4067/S0717-65382004000300047.
Title: ACOUSTIC REMOTE SENSING OF LARGE-SCALE TEMPERATURE VARIABILITY IN THE NORTH PACIFIC OCEAN
Type: Journal Article
Publication: Gayana (Concepción)
Author(s): Worcester, Peter F; Cornuelle, Bruce D; Dushaw, Brian D.; Dzieciuch, Matthew A; Howe, Bruce M; Menemenlis, Dimitris; Mercer, James A; Munk, Walter H; Spindel, Robert C; Stammer, Detlef; Zarnetske, Michael
Year: 2004
Formatted Citation: Worcester, P. F. and Coauthors, 2004: ACOUSTIC REMOTE SENSING OF LARGE-SCALE TEMPERATURE VARIABILITY IN THE NORTH PACIFIC OCEAN. Gayana (Concepción), 68(2), 576-577, doi:10.4067/S0717-65382004000300047
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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McKinley, Galen A.; Follows, Michael J.; Marshall, J (2004). Mechanisms of air-sea CO2 flux variability in the equatorial Pacific and the North Atlantic, Global Biogeochemical Cycles, 2 (18), 10.1029/2003gb002179.
Title: Mechanisms of air-sea CO2 flux variability in the equatorial Pacific and the North Atlantic
Type: Journal Article
Publication: Global Biogeochemical Cycles
Author(s): McKinley, Galen A.; Follows, Michael J.; Marshall, J
Year: 2004
Formatted Citation: McKinley, G. A., M. J. Follows, and J. Marshall, 2004: Mechanisms of air-sea CO2 flux variability in the equatorial Pacific and the North Atlantic. Global Biogeochemical Cycles, 18(2), doi:10.1029/2003gb002179
Abstract: A global ocean general circulation model is used to estimate the magnitude of interannual variability in air-sea fluxes of CO2 and O-2 from 1980-1998 and to examine the controlling mechanisms. The global variability in the air-sea flux of carbon (+/-0.5 x 10(15) grams Carbon yr(-1) (PgC yr(-1))) is forced by changes of DeltapCO(2) and wind speeds related to the El Nino/Southern Oscillation (ENSO) cycle in the equatorial Pacific. In contrast the air-sea O-2 flux is controlled by two regions: the equatorial Pacific and North Atlantic. The model captures much of the interannual variability of the CO2 flux observed at Bermuda, with some correlation with the North Atlantic Oscillation (NAO) index. However, basin-scale air-sea CO2 flux anomalies are not correlated with the NAO due to a rapid neutralization of entrained DIC anomalies by biological uptake and export production in the subpolar gyre. CO2 flux variability estimates from our ocean model and the mean atmospheric inversion results of Bousquet et al. [2000] are in broad agreement in the equatorial Pacific, but not in the North Atlantic. This model suggests that the projection of air-sea flux anomalies onto the large-scale, mean air-sea flux pattern in atmospheric inversions may lead to an overestimate of the flux variability in the extra-tropics where the patterns of variability do not correspond to those of the mean flux.
Keywords: air-sea exchange, atmospheric transport, carbon flux, carbon-cycle, circulation model, el-nino, gas-exchange, interannual variability, nino-southern oscillation, ocean, ocean modeling, subtropical gyre, surface temperature
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Wang, O; Fukumori, I; Lee, T; Johnson, G C (2004). Eastern equatorial Pacific Ocean T-S variations with El Nino, Geophysical Research Letters, 4 (31), L04305, 10.1029/2003gl019087.
Title: Eastern equatorial Pacific Ocean T-S variations with El Nino
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Wang, O; Fukumori, I; Lee, T; Johnson, G C
Year: 2004
Formatted Citation: Wang, O., I. Fukumori, T. Lee, and G. C. Johnson, 2004: Eastern equatorial Pacific Ocean T-S variations with El Nino. Geophys. Res. Lett., 31(4), L04305, doi:10.1029/2003gl019087
Abstract: Temperature-Salinity (T-S) relationship variability in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5 degreesS - 5 degreesN, 150 degreesW - 90 degreesW) over the last two decades is investigated using observational data and model simulation. A numerical model simulation using the MITgcm ( Massachusetts Institute of Technology General Circulation Model) suggests that, during El Nino years, the water in the eastern equatorial Pacific Ocean becomes saltier (by 0.1 to 0.2) and warmer (by 0.5 to 1 degreesC) on density surfaces within the pycnocline. This simulation is consistent with Conductivity-Temperature-Depth (CTD) data collected mostly during Tropical Atmosphere Ocean (TAO) mooring maintenance cruises.
Keywords: circulation, la-nina, model, volume
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Vivier, Frédéric; Maier-Reimer, Ernst; Tyler, Robert H. (2004). Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow?, Geophysical Research Letters, 10 (31), 1-5, 10.1029/2004GL019804.
Title: Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow?
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Vivier, Frédéric; Maier-Reimer, Ernst; Tyler, Robert H.
Year: 2004
Formatted Citation: Vivier, F., E. Maier-Reimer, and R. H. Tyler, 2004: Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow? Geophys. Res. Lett., 31(10), 1-5, doi:10.1029/2004GL019804
Abstract: With a volume transport of ~134
Keywords:
ECCO Products Used: ECCO-KFS
URL:
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Chen, J. L.; Wilson, C. R.; Tapley, B. D.; Ries, J. C. (2004). Low degree gravitational changes from GRACE: Validation and interpretation, Geophysical Research Letters, 22 (31), 10.1029/2004GL021670.
Title: Low degree gravitational changes from GRACE: Validation and interpretation
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Chen, J. L.; Wilson, C. R.; Tapley, B. D.; Ries, J. C.
Year: 2004
Formatted Citation: Chen, J. L., C. R. Wilson, B. D. Tapley, and J. C. Ries, 2004: Low degree gravitational changes from GRACE: Validation and interpretation. Geophys. Res. Lett., 31(22), doi:10.1029/2004GL021670
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
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Gross, R S; Fukumori, I; Menemenlis, Dimitris; Gegout, P (2004). Atmospheric and oceanic excitation of length-of-day variations during 1980-2000, Journal of Geophysical Research-Solid Earth, B1 (109), B01406, 10.1029/2003jb002432.
Title: Atmospheric and oceanic excitation of length-of-day variations during 1980-2000
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Gross, R S; Fukumori, I; Menemenlis, Dimitris; Gegout, P
Year: 2004
Formatted Citation: Gross, R. S., I. Fukumori, D. Menemenlis, and P. Gegout, 2004: Atmospheric and oceanic excitation of length-of-day variations during 1980-2000. Journal of Geophysical Research-Solid Earth, 109(B1), B01406, doi:10.1029/2003jb002432
Abstract: [1] Although nontidal changes in the Earth's length-of-day on timescales of a few days to a few years are primarily caused by changes in the angular momentum of the zonal winds, other processes can be expected to cause the length-of-day to change as well. Here the relative contribution of upper atmospheric winds, surface pressure, oceanic currents, and ocean-bottom pressure to changing the length-of-day during 1980 - 2000 is evaluated using estimates of atmospheric angular momentum from the National Centers for Environmental Prediction/ National Center for Atmospheric Research reanalysis project, estimates of the angular momentum of the zonal winds in the upper atmosphere from the United Kingdom Meteorological Office, and estimates of oceanic angular momentum from the Estimating the Circulation and Climate of the Ocean consortium's simulation of the general circulation of the oceans. On intraseasonal timescales, atmospheric surface pressure, oceanic currents, and ocean-bottom pressure are found to be about equally important in causing the length-of-day to change, while upper atmospheric winds are found to be less important than these mechanisms. On seasonal timescales, the upper atmospheric winds are more important than the sum of currents and bottom pressure in causing the length-of-day to change and, except at the annual frequency, are even more important than surface pressure changes. On interannual timescales, oceanic currents and ocean-bottom pressure are found to be only marginally effective in causing the length-of-day to change.
Keywords: axial angular-momentum, bottom pressure, boussinesq approximation, earth rotation, earths rotation, general-circulation, global ocean, length-of-day, model, oceanic angular momentum, polar motion, sea-level, seasonal budget
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Wang, O; Fukumori, I; Lee, T; Cheng, B (2004). On the cause of eastern equatorial Pacific Ocean T-S variations associated with El Nino, Geophysical Research Letters, 15 (31), 10.1029/2004gl020188.
Title: On the cause of eastern equatorial Pacific Ocean T-S variations associated with El Nino
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Wang, O; Fukumori, I; Lee, T; Cheng, B
Year: 2004
Formatted Citation: Wang, O., I. Fukumori, T. Lee, and B. Cheng, 2004: On the cause of eastern equatorial Pacific Ocean T-S variations associated with El Nino. Geophys. Res. Lett., 31(15), doi:10.1029/2004gl020188
Abstract: The nature of observed variations in temperature-salinity (T-S) relationship between El Nino and non-El Nino years in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5degreesS-5degreesN, 150degreesW-90degreesW) is investigated using an ocean general circulation model. The origin of the subject water mass is identified using the adjoint of a simulated passive tracer. The higher salinity during El Nino is attributed to larger convergence of saltier water from the Southern Hemisphere and smaller convergence of fresher water from the Northern Hemisphere.
Keywords: boundary, circulation, model, salinity variability, tropical pacific
ECCO Products Used: ECCO-KFS
URL:
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Lee, T; Fukumori, I; Tang, B (2004). Temperature advection: Internal versus external processes, Journal of Physical Oceanography, 8 (34), 1936-1944, 10.1175/1520-0485(2004)034<1936:Taivep>2.0.Co;2.
Title: Temperature advection: Internal versus external processes
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Lee, T; Fukumori, I; Tang, B
Year: 2004
Formatted Citation: Lee, T., I. Fukumori, and B. Tang, 2004: Temperature advection: Internal versus external processes. Journal of Physical Oceanography, 34(8), 1936-1944, doi:10.1175/1520-0485(2004)034<1936:Taivep>2.0.Co;2
Abstract: Local advection of temperature is the inner product of vector velocity and spatial gradient of temperature. This product is often integrated spatially to infer temperature advection over a region. However, the contribution along an individual direction can be dominated by internal processes that redistribute heat within the domain but do not control the heat content of the domain. A new formulation of temperature advection is introduced to elucidate external heat source and sink that control the spatially averaged temperature. It is expressed as the advection of interfacial temperature relative to the spatially averaged temperature of the domain by inflow normal to the interface. It gives a total advection of temperature that is identical to the spatial integration of local temperature advection, yet the contributions along individual directions depict external processes. The differences between the two formulations are illustrated by analyzing zonal advection of near-surface temperature in the eastern equatorial Pacific during the 1997-98 El Nino and the subsequent La Nina by an ocean general circulation model. The new formulation highlights the advection of warmer water at the western side of the Nino-3 region into (out of) the region to create part of the warming (cooling) tendency during El Nino (La Nina). In contrast, the traditional formulation is dominated by the effect of tropical instability waves within the region that redistribute heat internally. The difference between the two formulations suggests a need for caution in discerning mechanisms controlling heat content of a region. Spatial integration of local temperature advection does not explain external processes that control a domain's heat content. The conclusion applies not only to the advection of oceanic temperature, but also to that of any property in any medium.
Keywords: 1997-98 el-nino, equatorial pacific, heat-budget, mechanisms, model, ocean
ECCO Products Used: ECCO-KFS
URL:
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Chen, J.-L.; Wilson, C R; Hu, X.-G.; Zhou, Y.-H.; Tapley, B D (2004). Oceanic effects on polar motion determined from an ocean model and satellite altimetry: 1993-2001, Journal of Geophysical Research: Solid Earth, B2 (109), 10.1029/2003JB002664.
Title: Oceanic effects on polar motion determined from an ocean model and satellite altimetry: 1993-2001
Type: Journal Article
Publication: Journal of Geophysical Research: Solid Earth
Author(s): Chen, J.-L.; Wilson, C R; Hu, X.-G.; Zhou, Y.-H.; Tapley, B D
Year: 2004
Formatted Citation: Chen, J., C. R. Wilson, X. Hu, Y. Zhou, and B. D. Tapley, 2004: Oceanic effects on polar motion determined from an ocean model and satellite altimetry: 1993-2001. Journal of Geophysical Research: Solid Earth, 109(B2), doi:10.1029/2003JB002664
Abstract: Mass redistribution and motion in the oceans are major driving forces of geodetic variations, including polar motion, length of day, geocenter, and gravity field changes. We examine oceanic contribution to polar motion using estimates from a data-assimilating ocean general circulation model and satellite radar altimeter observations. The data include model estimates of variations in oceanic mass (OBP) and meridional and zonal velocities. Sea level anomalies from TOPEX/Poseidon (T/P) satellite altimeter measurements and steric sea surface height changes deduced from the model are also used to estimate OBP effects. Estimated oceanic contributions from both the model and T/P show considerably better agreement with polar motion observations compared with results from previous studies. The improvement is particularly significant at intraseasonal timescales. Both OBP and ocean current variations provide important contributions to polar motion. At intraseasonal timescales the oceans appear to be a dominant contributor to residual polar motion not accounted for by the atmosphere. The oceans also play an important role in seasonal excitation. Combined OBP and ocean current contributions explain much of the residual semiannual variability.
Keywords: OGCM, ocean, polar motion, satellite altimeter
ECCO Products Used: ECCO-KFS
Other URLs:
Kolaczek, B.; Nastula, J. (2004). Impact of the addition of the ocean to the atmospheric excitation ofpolar motion on variability of spectra and correlation with polar motion, Proceedings of the Journées 2003 "Systèmes deréférence spatio-temporels": Astrometry, Geodynamics and Solar System Dynamics: from milliarcseconds to microarcseconds, held at IAA, , 22-25 September 2003, 150-155.
Title: Impact of the addition of the ocean to the atmospheric excitation ofpolar motion on variability of spectra and correlation with polar motion
Type: Conference Proceedings
Publication: Proceedings of the Journées 2003 "Systèmes deréférence spatio-temporels": Astrometry, Geodynamics and Solar System Dynamics: from milliarcseconds to microarcseconds, held at IAA, , 22-25 September 2003
Author(s): Kolaczek, B.; Nastula, J.
Year: 2004
Formatted Citation: Kolaczek, B., and J. Nastula, 2004: Impact of the addition of the ocean to the atmospheric excitation ofpolar motion on variability of spectra and correlation with polar motion. Proceedings of the Journées 2003 "Systèmes deréférence spatio-temporels": Astrometry, Geodynamics and Solar System Dynamics: from milliarcseconds to microarcseconds, held at IAA, , 22-25 September 2003, A. Finkelstein, and N. Capitaine, Eds., St.Petersburg, Russia, 150-155 pp. http://syrte.obspm.fr/jsr/journees2003/pdf/s2_09_Kolaczek.pdf.
Abstract: Impact of the addition of the ocean to the atmospheric excitation ofpolar motion on variability of spectra of polar motion and correlationwith polar motion is investigated. Variations of the seasonal andsubseasonal spectra of the atmospheric and joint atmospheric plusoceanic excitation functions of polar motion and their time variationsare computed by the Fourier Transform Function and compared. Thesespectra are very similar. Correlations between geodetic and eitheratmospheric or joint atmospheric plus oceanic excitation functions arecomputed in four spectra bands range from 10 to 500 days. In all casescorrelation coefficients for joint atmospheric plus oceanic excitationfunctions are higher and more stable than for atmospheric excitationfunction.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Howe, Bruce M.; Cornuelle, Bruce D.; Dushaw, Brian D.; Dzieciuch, Matthew A.; Menemenlis, Dimitris; Mercer, James A.; Munk, Walter H.; Spindel, Robert C.; Stammer, Detlef; Worcester, Peter F.; Zarnetske, M. R. (2004). Acoustic remote sensing of large-scale temperature variability in the North Pacific Ocean, OCEANS `04 MTS/IEEE TECHNO-OCEAN, 1504-1506.
Title: Acoustic remote sensing of large-scale temperature variability in the North Pacific Ocean
Type: Conference Proceedings
Publication: OCEANS `04 MTS/IEEE TECHNO-OCEAN
Author(s): Howe, Bruce M.; Cornuelle, Bruce D.; Dushaw, Brian D.; Dzieciuch, Matthew A.; Menemenlis, Dimitris; Mercer, James A.; Munk, Walter H.; Spindel, Robert C.; Stammer, Detlef; Worcester, Peter F.; Zarnetske, M. R.
Year: 2004
Formatted Citation: Howe, B. M. and Coauthors, 2004: Acoustic remote sensing of large-scale temperature variability in the North Pacific Ocean. OCEANS `04 MTS/IEEE TECHNO-OCEAN, 1504-1506 pp.
Abstract: Large-scale, depth-averaged temperatures have been measured by long-range acoustic transmissions in the North Pacific Ocean for the past nine years. Acoustic sources located off central California and north of Kauai transmitted to receivers distributed throughout the North Pacific from 1996 through 1999 during the Acoustic Thermometry of Ocean Climate (ATOC) project. The Kauai transmissions resumed in early 2002 and are now continuing as part of the North Pacific Acoustic Laboratory (NPAL) project; a six-year time series has been obtained so far. Even at long time and large spatial scales the ocean is highly variable. The paths from Kauai to California show a modest cooling trend (longer travel times) until the present time. A path to the northwest showed modest warming and a weak annual cycle from 1999 until early 2003, when a strong annual cycle returned. In retrospect, these changes stemmed from the warming of the central Pacific that occurred in this interval, possibly associated with the Pacific Decadal Oscillation (PDO). Comparisons between measured travel times and those predicted using ocean models, constrained by satellite altimeter and other data, show significant similarities and differences. Comparison between upper-ocean Argo profiling float temperatures and the acoustically measured temperature along one path illustrates the strength of the integral measurements, with substantially lower uncertainty. The acoustic data ultimately need to be combined with sea-surface height Argo float data to determine the complementarity of the various data types. In particular, combining the acoustic and Argo data by inverse techniques will quantify the ability of the float data to resolve large-scale, upper-ocean heat content and the ability of the acoustic data to resolve abyssal temperature changes.
Keywords:
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
di Leonardo, Susan M.; Dickman, S. R. (2004). Isolation of atmospheric effects on rapid polar motion through Wiener filtering, Geophysical Journal International, 3 (159), 863-873, 10.1111/j.1365-246X.2004.02445.x.
Title: Isolation of atmospheric effects on rapid polar motion through Wiener filtering
Type: Journal Article
Publication: Geophysical Journal International
Author(s): di Leonardo, Susan M.; Dickman, S. R.
Year: 2004
Formatted Citation: di Leonardo, S. M., and S. R. Dickman, 2004: Isolation of atmospheric effects on rapid polar motion through Wiener filtering. Geophysical Journal International, 159(3), 863-873, doi:10.1111/j.1365-246X.2004.02445.x
Abstract:
Keywords: Atmospheric excitation, Ocean tides, Ocean-atmosphere interactions, Rapid polar motion, Rotational variations, Wiener filtering
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Nastula, J.; Gambis, D. (2004). Excitation of Polar Motion By Atmospheric and Oceanic, Journées 2004, Systèmes de référence spatio-temporels, Fundamental Astronomy: New concepts and models for high accuracy observations, 148-149.
Title: Excitation of Polar Motion By Atmospheric and Oceanic
Type: Conference Proceedings
Publication: Journées 2004, Systèmes de référence spatio-temporels, Fundamental Astronomy: New concepts and models for high accuracy observations
Author(s): Nastula, J.; Gambis, D.
Year: 2004
Formatted Citation: Nastula, J., and D. Gambis, 2004: Excitation of Polar Motion By Atmospheric and Oceanic. Journées 2004, Systèmes de référence spatio-temporels, Fundamental Astronomy: New concepts and models for high accuracy observations, N. Capitaine, Eds. Observatoire de Paris, Paris, 148-149 pp. https://www.researchgate.net/profile/Tim_Van_Hoolst/publication/237726688_THE_COUPLING_EQUATIONS_BETWEEN_THE_NUTATION_AND_THE_GEOMAGNETIC_FIELD_IN_GSH_EXPANSION/links/0f31752df85bf82ff5000000/THE-COUPLING-EQUATIONS-BETWEEN-THE-NUTATION-AND-THE-GEOMAGNETIC.
Abstract: It is widely accepted that atmospheric and oceanic variabilities play a major role in the excitation of polar motion at period longer than 10 days. However for shorter periods the effect is not clear. We have reanalysed the role of Atmospheric Angular Momentum (AAM) and Oceanic Angular Momentum (OAM) variabilities on the excitation of high frequency polar motion variations taking advantage of a recent Oceanic Angular Momentum (OAM) series derived by Ponte and Ali. We show that the correlation significant at periods between 2 and 10 days.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Fukumori, I; Lee, T; Cheng, B; Menemenlis, Dimitris (2004). The origin, pathway, and destination of Nino-3 water estimated by a simulated passive tracer and its adjoint, Journal of Physical Oceanography, 3 (34), 582-604, 10.1175/2515.1.
Title: The origin, pathway, and destination of Nino-3 water estimated by a simulated passive tracer and its adjoint
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Fukumori, I; Lee, T; Cheng, B; Menemenlis, Dimitris
Year: 2004
Formatted Citation: Fukumori, I., T. Lee, B. Cheng, and D. Menemenlis, 2004: The origin, pathway, and destination of Nino-3 water estimated by a simulated passive tracer and its adjoint. Journal of Physical Oceanography, 34(3), 582-604, doi:10.1175/2515.1
Abstract: The nature of subtropical - tropical water mass exchange in the Pacific Ocean is investigated, focusing on the origin, pathway, and destination of water occupying the surface layer of the eastern equatorial Pacific Ocean (Nino-3 region; 5degreesS - 5degreesN, 150degrees - 90degreesW). Simulated passive tracers and their adjoint are employed to explicitly follow the circulation of specific water masses accounting for advective and diffusive effects and their time variabilities. The evolution of the forward passive tracer and adjoint passive tracer can be identified as describing where the tracer-tagged water mass goes and from where it comes, respectively. Over 10 years on average, water mass of the Nino-3 region can be traced back to eastern subtropical thermocline waters of the Northern (27%) and Southern Hemispheres (39%). The Nino-3 water subsequently returns to these subtropical latitudes in the upper ocean. In contrast to the hypothesized "subtropical cell,'' however, this circulation is an open circuit with water returning to the western regions of the two hemispheres ( subtropical gyres) and to the Indian Ocean, instead of returning to its origins. The representative transit time scale from the subtropics to the Tropics is 10 15 yr. Temporal variability causes the tropical circulation inferred from a time-mean state to differ significantly from the average circulation. In particular, stirring due to nonseasonal, intra-annual variability significantly enhances the transport magnitude of the so-called interior pathways relative to that of the circuitous low-latitude western boundary pathways. Such short-circuit in the subtropical - tropical exchange may help better to explain tracer distributions, such as the observed midbasin tritium maximum in the equatorial Pacific Ocean. Significant differences in circulation pathways are also identified that are associated with El Nino and La Nina events. The strength of the subtropical - tropical water mass exchange is estimated to have weakened during the 1990s.
Keywords: circulation model, el-nino, environmental prediction, equatorial pacific-ocean, exchange, national centers, north pacific, thermocline water, tritium maximum, tropical pacific
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Kim, S B; Lee, T; Fukumori, I (2004). The 1997-1999 abrupt change of the upper ocean temperature in the north central Pacific, Geophysical Research Letters, 22 (31), 10.1029/2004gl021142.
Title: The 1997-1999 abrupt change of the upper ocean temperature in the north central Pacific
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Kim, S B; Lee, T; Fukumori, I
Year: 2004
Formatted Citation: Kim, S. B., T. Lee, and I. Fukumori, 2004: The 1997-1999 abrupt change of the upper ocean temperature in the north central Pacific. Geophys. Res. Lett., 31(22), doi:10.1029/2004gl021142
Abstract: The abrupt warming of the north central Pacific Ocean from 1997 to 1999 is studied using an ocean data assimilation product. During this period, the average mixed-layer temperature in the region of 170 - 210 degreesE, 25 - 40 degreesN rises by 1.8 K. The major contributors to the warming are surface heat flux ( 1.3 K), geostrophic advection (0.7 K), and entrainment ( 0.7 K). For the geostrophic advection, the contributions by the zonal, meridional, and vertical components are 0.4, - 0.1 and 0.3 K, respectively. Mixing and meridional Ekman advection have cooling effect. The significance of the geostrophic advection indicates the importance of ocean dynamics in controlling the abrupt warming tendency during the 1997 - 99 period and the inadequacy of a slabmixed-layer model in simulating such warming tendency.
Keywords: america, anomalies, decadal climate variability, dynamics, ecosystems, flux, heat-budget, model
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Chen, J. L.; Wilson, C. R. (2003). Low degree gravitational changes from earth rotation and geophysical models, Geophysical Research Letters, 24 (30), 10.1029/2003GL018688.
Title: Low degree gravitational changes from earth rotation and geophysical models
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Chen, J. L.; Wilson, C. R.
Year: 2003
Formatted Citation: Chen, J. L., and C. R. Wilson, 2003: Low degree gravitational changes from earth rotation and geophysical models. Geophys. Res. Lett., 30(24), doi:10.1029/2003GL018688
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Stammer, Detlef (2003). Routine ECCO ocean syntheses available through the internet, CLIVAR Exchanges, 1 (8), 14.
Title: Routine ECCO ocean syntheses available through the internet
Type: Magazine Article
Publication: CLIVAR Exchanges
Author(s): Stammer, Detlef
Year: 2003
Formatted Citation: Stammer, D., 2003: Routine ECCO ocean syntheses available through the internet. CLIVAR Exchanges, 8(1), 14 pp. http://eprints.uni-kiel.de/7837/1/Exchanges26.pdf#page=14.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0
Other URLs:
Lee, Tong; Fukumori, Ichiro (2003). Interannual-to-Decadal Variations of Tropical-Subtropical Exchange in the Pacific Ocean: Boundary versus Interior Pycnocline Transports, Journal of Climate, 24 (16), 4022-4042, 10.1175/1520-0442(2003)016<4022:IVOTEI>2.0.CO;2.
Title: Interannual-to-Decadal Variations of Tropical-Subtropical Exchange in the Pacific Ocean: Boundary versus Interior Pycnocline Transports
Type: Journal Article
Publication: Journal of Climate
Author(s): Lee, Tong; Fukumori, Ichiro
Year: 2003
Formatted Citation: Lee, T., and I. Fukumori, 2003: Interannual-to-Decadal Variations of Tropical-Subtropical Exchange in the Pacific Ocean: Boundary versus Interior Pycnocline Transports. J. Clim., 16(24), 4022-4042, doi:10.1175/1520-0442(2003)016<4022:IVOTEI>2.0.CO;2
Abstract: Interannual-to-decadal variations of tropical - subtropical mass exchange in the Pacific Ocean are investigated using a near-global ocean general circulation model along with satellite observations of sea level and wind and a data assimilation product. The analysis focuses on the variability of pycnocline transports through the western boundary and interior near 10degreesN and 10degreesS. In contrast to time-mean exchange, where boundary and interior pycnocline transports are both equatorward, the variations of boundary and interior pycnocline transports are found to be generally anticorrelated to each other. Moreover, the variation of the boundary pycnocline transport is smaller than that of the interior, again different from time-mean exchange, where the boundary transport at 10degreesN is substantially larger than that through the interior. Interannual variations of the boundary and interior transports are consistent with near-surface geostrophic flow inferred from sea level data. Interior pycnocline flow into the Tropics is weaker in the 1990s than that in the 1980s, in agreement with recent observations. However, approximately half of it is compensated by an opposite change in boundary flow at 10degreesN. The results indicate that the interior pathway is more important to interannual and decadal variability of tropical - subtropical exchange than the boundary pathway, despite a much larger time-mean transport of the western boundary current at 10degreesN. To a large extent, the counteracting tendency of the boundary and interior flow and the larger variation of the latter can be explained by the combined effect of variability in off-equatorial wind stress curl in the western Pacific and near-equatorial zonal wind stress. The former changes the strength of horizontal circulation and results in a variation of boundary pycnocline flow that is opposite in direction but comparable in magnitude to that of the interior pycnocline flow. The latter primarily affects the strength of the shallow meridional overturning circulation with net pycnocline flow ( mostly in the interior) opposing the surface Ekman flow. The covariability of these two forcings leads to an enhancement of interior transport. The relative variability of boundary and interior pycnocline flow is insensitive to whether the Indonesian Throughflow is present or not.
Keywords: circulation, el-nino, equatorial pacific, heat-content variability, indonesian throughflow, mindanao current, model, north pacific, thermocline, water exchange
ECCO Products Used: ECCO-KFS
Other URLs:
Gross, R S; Fukumori, I; Menemenlis, Dimitris (2003). Atmospheric and oceanic excitation of the Earth’s wobbles during 1980-2000, Journal of Geophysical Research-Solid Earth, B8 (108), 10.1029/2002jb002143.
Title: Atmospheric and oceanic excitation of the Earth’s wobbles during 1980-2000
Type: Journal Article
Publication: Journal of Geophysical Research-Solid Earth
Author(s): Gross, R S; Fukumori, I; Menemenlis, Dimitris
Year: 2003
Formatted Citation: Gross, R. S., I. Fukumori, and D. Menemenlis, 2003: Atmospheric and oceanic excitation of the Earth's wobbles during 1980-2000. Journal of Geophysical Research-Solid Earth, 108(B8), doi:10.1029/2002jb002143
Abstract: Because of the action of various geophysical excitation mechanisms, the Earth does not rotate about its figure axis, so it wobbles as it rotates. Here, the effectiveness of atmospheric and oceanic processes in exciting the Earth's wobbles during 1980-2000 is evaluated using estimates of atmospheric angular momentum from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis project and estimates of oceanic angular momentum from the Estimating the Circulation and Climate of the Ocean (ECCO) consortium's simulation of the general circulation of the oceans. On intraseasonal timescales, atmospheric surface pressure changes are found to be the single most effective process exciting the Earth's wobbles, explaining about twice as much of the observed variance as do either atmospheric wind or ocean bottom pressure changes and nearly 4 times as much of the observed variance as do oceanic currents. However, on interannual timescales, ocean bottom pressure changes are found to be the single most effective process exciting the Earth's wobbles, explaining more than 5 times as much of the observed variance as do atmospheric wind and pressure changes combined, and more than twice as much of the observed variance as do oceanic currents. Within the Chandler band it is found that during 1980-2000 atmospheric and oceanic processes have enough power to excite the Chandler wobble and are significantly coherent with it. The single most important mechanism exciting the Chandler wobble is found to be ocean bottom pressure variations. Atmospheric and oceanic processes do not appear to have enough power to excite the Earth's wobbles to their observed levels on pentadal and longer timescales, although series longer than the 21-year long series used here need to be studied in order to obtain greater statistical significance of this result.
Keywords: angular-momentum, atmospheric angular momentum, base-line interferometry, chandler wobble, chandler-wobble, earth rotation, gravitational-field, model, oceanic angular momentum, orientation, polar motion, polar motion excitation, rotation, sea-level, short periodic variations
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Fieguth, P W; Menemenlis, Dimitris; Fukumori, I (2003). Mapping and pseudoinverse algorithms for ocean data assimilation, Ieee Transactions on Geoscience and Remote Sensing, 1 (41), 43-51, 10.1109/Tgrs.2002.808058.
Title: Mapping and pseudoinverse algorithms for ocean data assimilation
Type: Journal Article
Publication: Ieee Transactions on Geoscience and Remote Sensing
Author(s): Fieguth, P W; Menemenlis, Dimitris; Fukumori, I
Year: 2003
Formatted Citation: Fieguth, P. W., D. Menemenlis, and I. Fukumori, 2003: Mapping and pseudoinverse algorithms for ocean data assimilation. Ieee Transactions on Geoscience and Remote Sensing, 41(1), 43-51, doi:10.1109/Tgrs.2002.808058
Abstract: Among existing ocean data assimilation methodologies, reduced-state Kalman filters are a widely studied compromise between resolution, optimality, error specification, and computational feasibility. In such reduced-state filters, the measurement update takes place on a coarser grid than that of the general circulation model (GCM); therefore, these filters require mapping operators from the GCM grid to the reduced state and vice versa. The general requirements are that the state-reduction and interpolation operators be pseudoinverses of each other, that the coarse state define a closed dynamical system, that the mapping operations be insensitive to noise, and that they be appropriate for regions with irregular coastlines and bathymetry. In this paper, we describe three efficient algorithms for computing the pseudoinverse: a fast Fourier transform algorithm that serves for illustration purposes, an exact implicit method that is recommended for most applications, and an efficient iterative algorithm that can be used for the largest problems. The mapping performance of 11 interpolation kernels is evaluated. Surprisingly, common kernels such as bilinear, exponential, Gaussian, and sine perform only moderately well. We recommend instead three kernels, smooth, thin-plate, and optimal interpolation, which have superior properties. This study removes the computational bottleneck of mapping and pseudoinverse algorithms and makes possible the application of reduced-state filters to global problems at state-of-the-art resolutions.
Keywords: altimeter data, circulation model, climatological models, data assimilation, extended kalman filter, interscale transforms, pseudoinverse methods, remote sensing, sea-level, sparse pseudoinverses, tropical pacific-ocean
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Hu, X.-G.; Chen, J.-L.; Huang, C.; Tapley, B.D.; Wilson, C.R. (2003). Non-tidal oceanic contribution to the variation of the earth oblateness, Acta Geophysica Sinica, 3 (47), 484-489.
Title: Non-tidal oceanic contribution to the variation of the earth oblateness
Type: Journal Article
Publication: Acta Geophysica Sinica
Author(s): Hu, X.-G.; Chen, J.-L.; Huang, C.; Tapley, B.D.; Wilson, C.R.
Year: 2003
Formatted Citation: Hu, X., J. Chen, C. Huang, B. Tapley, and C. Wilson, 2003: Non-tidal oceanic contribution to the variation of the earth oblateness. Acta Geophysica Sinica, 47(3), 484-489
Abstract: We investigate two ocean models for model validation and the altimetry data from TOPEX/Poseidon (T/P) and conclude that the mass transfer within the oceans, specifically within the Pacific Ocean, contribute to at least part of the variation of the Earth oblateness ( J 2 ) since 1997/1998. The abnormal J 2 variation since 1997/1998 may be from the variations of the steric effects, which are the result of thermal and saline variation, and might not be easily discerned from the sea surface height variations observed with the T/P data.
Keywords: Gravity change, Mass transfer, Oceanic circulation, Satellite laser ranging
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Chao, B F; Au, A Y; Boy, J P; Cox, C M (2003). Time-variable gravity signal of an anomalous redistribution of water mass in the extratropic Pacific during 1998-2002, Geochemistry Geophysics Geosystems (4), 10.1029/2003gc000589.
Title: Time-variable gravity signal of an anomalous redistribution of water mass in the extratropic Pacific during 1998-2002
Type: Journal Article
Publication: Geochemistry Geophysics Geosystems
Author(s): Chao, B F; Au, A Y; Boy, J P; Cox, C M
Year: 2003
Formatted Citation: Chao, B. F., A. Y. Au, J. P. Boy, and C. M. Cox, 2003: Time-variable gravity signal of an anomalous redistribution of water mass in the extratropic Pacific during 1998-2002. Geochemistry Geophysics Geosystems, 4, doi:10.1029/2003gc000589
Abstract: Cox and Chao [2002] reported the detection of a large anomaly in the time series of Earth's dynamic oblateness J(2), the lowest-degree gravity spatial harmonic, in the form of a positive jump since 1998 overshadowing the decreasing secular trend in J(2) caused primarily by the postglacial rebound (PGR). Here we report that recent data show that J(2) has been rapidly returning toward "normal'' (with PGR considered) since early 2001. In search of the geophysical and climatic causes for this "1998-2002 J(2) anomaly,'' we report an oceanographic event that took place in the extratropic north and south Pacific basins that was found to match remarkably well with the time evolution of the anomaly. We examine the leading (nonseasonal, extratropic Pacific) Empirical Orthogonal Function/Principal Component modes in the sea-surface height (SSH) data from TOPEX/Poseidon, sea surface temperature (SST) data from the National Center for Environmental Predictions, and output fields of the Estimating the Circulation and the Climate of the Ocean (ECCO) ocean general circulation model (OGCM), including ocean bottom pressure (OBP) and temperature and salinity profiles. The phenomenon appears to be part of the Pacific Decadal Oscillation, and temporal correlations are made. However, quantitatively, the OBP field of the ECCO model predicts a J(2) anomaly that is smaller in magnitude than the observed by a factor of about 3. We discuss various possibilities for reconciling this discrepancy in terms of inadequacies of present OGCMs and considering other geophysical contributions; a complete resolution of the J(2) enigma awaits further studies.
Keywords: J(2) anomaly, circulation, climate, distribution, earth rotation, el-nino, extratropic Pacific, field, geodesy and gravity : ocean/earth/atmosphere inter, interdecadal variability, lageos, model, ocean, oceanography : general : climate and interannual v, oscillation, time-variable gravity, water mass
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Howe, B.M.; Dushaw, Brian D.; Mercer, J.A.; Worcester, P.F.; Colosi, J.A.; Cornuelle, B.C.; Dzieciuch, M.A.; Spindel, R.C. (2003). Acoustic thermometry time series in the North Pacific, 2003 International Conference Physics and Control. Proceedings (Cat. No.03EX708), 111-114, 10.1109/SSC.2003.1224123.
Title: Acoustic thermometry time series in the North Pacific
Type: Conference Proceedings
Publication: 2003 International Conference Physics and Control. Proceedings (Cat. No.03EX708)
Author(s): Howe, B.M.; Dushaw, Brian D.; Mercer, J.A.; Worcester, P.F.; Colosi, J.A.; Cornuelle, B.C.; Dzieciuch, M.A.; Spindel, R.C.
Year: 2003
Formatted Citation: Howe, B., B. D. Dushaw, J. Mercer, P. Worcester, J. Colosi, B. Cornuelle, M. Dzieciuch, and R. Spindel, 2003: Acoustic thermometry time series in the North Pacific. 2003 International Conference Physics and Control. Proceedings (Cat. No.03EX708) IEEE, 111-114 pp. doi:10.1109/SSC.2003.1224123.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Dushaw, Brian D. (2003). Acoustic thermometry in the North Pacific, CLIVAR Exchanges, 1 (8), 15-22.
Title: Acoustic thermometry in the North Pacific
Type: Magazine Article
Publication: CLIVAR Exchanges
Author(s): Dushaw, Brian D.
Year: 2003
Formatted Citation: Dushaw, B. D., 2003: Acoustic thermometry in the North Pacific. CLIVAR Exchanges, 8(1), 15-22 pp. http://eprints.uni-kiel.de/7837/1/Exchanges26.pdf#page=14.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Chen, J. L.; Wilson, C. R.; Hu, X. G.; Tapley, B. D. (2003). Large-scale mass redistribution in the oceans, 1993-2001, Geophysical Research Letters, 20 (30), 10.1029/2003GL018048.
Title: Large-scale mass redistribution in the oceans, 1993-2001
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): Chen, J. L.; Wilson, C. R.; Hu, X. G.; Tapley, B. D.
Year: 2003
Formatted Citation: Chen, J. L., C. R. Wilson, X. G. Hu, and B. D. Tapley, 2003: Large-scale mass redistribution in the oceans, 1993-2001. Geophys. Res. Lett., 30(20), doi:10.1029/2003GL018048
Abstract: A recent study of satellite laser ranging measurements by Cox and Chao[2002] indicates that large-scale mass redistribution has caused a rapid change in Earth's dynamic oblateness (J2) since 1998. Using satellite altimeter observations and two runs of an ocean general circulation models (OGCM), we examine mass variations in the oceans and their estimated effect on J2. Combined altimeter and OGCM results indicate variations similar to the J2 changes in 1998, and predict considerably larger oceanic effects on the J2 anomaly than purely OGCM estimates, suggesting that the oceans should not be ruled out by any means as a significant source of this interesting geodetic anomaly, until they have been studied further.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
McKinley, Galen A.; Follows, Michael J.; Marshall, J; Fan, S M (2003). Interannual variability of air-sea O2 fluxes and the determination of CO2 sinks using atmospheric O2/N2, Geophysical Research Letters, 3 (30), 10.1029/2002gl016044.
Title: Interannual variability of air-sea O2 fluxes and the determination of CO2 sinks using atmospheric O2/N2
Type: Journal Article
Publication: Geophysical Research Letters
Author(s): McKinley, Galen A.; Follows, Michael J.; Marshall, J; Fan, S M
Year: 2003
Formatted Citation: McKinley, G. A., M. J. Follows, J. Marshall, and S. M. Fan, 2003: Interannual variability of air-sea O2 fluxes and the determination of CO2 sinks using atmospheric O2/N2. Geophys. Res. Lett., 30(3), doi:10.1029/2002gl016044
Abstract: Motivated by the use of atmospheric O-2/N-2 to determine CO2 sinks under the assumption of negligible interannual variability in air-sea O-2 fluxes, we examine interannual fluctuations of the global air-sea flux of O-2 during the period 1980-1998 using a global ocean circulation and biogeochemistry model along with an atmospheric transport model. It is found that both the El Nino/Southern Oscillation (ENSO) cycle and wintertime convection in the North Atlantic are primary drivers of global air-sea oxygen flux interannual variability. Model estimated extremes of O-2 flux variability are -70/+100 x 10 12 mol/yr (Tmol/yr), where positive fluxes are to the atmosphere. O-2/N-2 variability could cause an up to +/-1.0 PgC/yr error in estimates of interannual variability in land and ocean CO2 sinks derived from atmospheric O-2/N-2 observations.
Keywords: carbon-cycle, circulation, model, north-atlantic, oxygen
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Ménard, Yves; Fu, Lee Lueng; Escudier, P.; Parisot, F.; Perbos, J.; Vincent, P.; Desai, S.; Haines, B.; Kunstmann, G. (2003). The Jason-1 Mission, Marine Geodesy, 3-4 (26), 131-146, 10.1080/714044514.
Title: The Jason-1 Mission
Type: Journal Article
Publication: Marine Geodesy
Author(s): Ménard, Yves; Fu, Lee Lueng; Escudier, P.; Parisot, F.; Perbos, J.; Vincent, P.; Desai, S.; Haines, B.; Kunstmann, G.
Year: 2003
Formatted Citation: Ménard, Y. and Coauthors, 2003: The Jason-1 Mission. Marine Geodesy, 26(3-4), 131-146, doi:10.1080/714044514
Abstract: On December 7, 2001, the Jason-1 satellite was successfully launched by a Boeing Delta II rocket from the Vandenberg site in California, USA. Its main mission was to maintain the high accuracy altimeter measurements, provided since 1992 by TOPEX/Poseidon (T/P), ensuring continuity in observing and monitoring the ocean for intraseasonal to interannual changes, mean sea level, tides, and so forth. Despite four times less mass and power, the Jason-1 system has been designed to have the same performances as T/P, measuring sea surface topography at the centimeter level. This new Centre National d'Etudes Spatiales/National Aeronautics and Space Administration (CNES/NASA) mission also provides near real-time data for sea state and ocean forecast. The first 10 months of the Jason mission were dedicated to the verification of the system performance and cross-calibration with T/P measurements. A complete CALVAL plan was conducted by the Science and Project Teams of the mission based on in situ and regional experiments, global statistical approaches, and multisatellite comparisons, taking advantage of the T/P-Jason overlap during the first months of the mission. CALVAL and first science results showed that the Jason-1 performances were compliant with prelaunch specifications. This was a needed preamble before starting the routine phase of the mission in July 2003 with generation and distribution of validated geophysical data records to the whole user community. [ABSTRACT FROM AUTHOR]
Keywords: Altimetry, CALVAL, JASON-1, Ocean dynamic topography, Operational oceonography, Satellite, Sea level, TOPEX/POSEIDON
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Fieguth, Paul W; Menemenlis, Dimitris; Fukumori, Ichiro (2002). Mapping and pseudo-inverse algorithms for data assimilation, IEEE International Geoscience and Remote Sensing Symposium (6), 3221-3223, 10.1109/IGARSS.2002.1027136.
Title: Mapping and pseudo-inverse algorithms for data assimilation
Type: Conference Proceedings
Publication: IEEE International Geoscience and Remote Sensing Symposium
Author(s): Fieguth, Paul W; Menemenlis, Dimitris; Fukumori, Ichiro
Year: 2002
Formatted Citation: Fieguth, P. W., D. Menemenlis, and I. Fukumori, 2002: Mapping and pseudo-inverse algorithms for data assimilation. IEEE International Geoscience and Remote Sensing Symposium IEEE, 6, 3221-3223 pp. doi:10.1109/IGARSS.2002.1027136.
Abstract: Among existing ocean data assimilation methodologies, reduced-state Kalman filters are a widely-studied compromise between resolution, optimality, error specification, and computational feasibility. In such reduced-state filters, the measurement update takes place on a coarser grid than that of the general circulation model (GCM); therefore, these filters require mapping operators from the GCM grid to the reduced state and vice-versa. The general requirements are that the state-reduction and interpolation operators be pseudo-inverses of each other, that the coarse state defines a closed dynamical system, that the mapping operations be insensitive to noise, and that they be appropriate for regions with irregular coastlines and bathymetry. In this paper we investigate a variety of approaches, including computing the pseudoinverse by brute force, using the FFT, subsampling methods, implicit methods, and finally develop a novel iterative approach. We also evaluate the mapping performance of eleven interpolation kernels; surprisingly, common kernels such as bilinear, exponential, Gaussian, and sinc, performed only moderately well. This comprehensive study greatly reduces the computational bottleneck and guesswork of pseudo-inverse algorithms, making possible the application of reduced-state filters to global problems at state-of-the-art resolution.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Halpern, David (2002). 2001 Annual Report- Climate Variability Program.
Title: 2001 Annual Report- Climate Variability Program
Type: Report
Publication:
Author(s): Halpern, David
Year: 2002
Formatted Citation: Halpern, D., 2002: 2001 Annual Report- Climate Variability Program., Pasadena, CA, 78 pp. https://ntrs.nasa.gov/search.jsp?R=20020048546.
Abstract: The Annual Report of the Climate Variability Program briefly describes research activities of Principal Investigators who are funded by NASA's Earth Science Enterprise Research Division. The report is focused on the year 2001. Utilization of satellite observations is a singularity of research on climate science and technology at JPL. Research at JPL has two foci: generate new knowledge and develop new technology.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Lee, T; Fukumori, I; Menemenlis, Dimitris; Xing, Z F; Fu, L L (2002). Effects of the Indonesian Throughflow on the Pacific and Indian oceans, Journal of Physical Oceanography, 5 (32), 1404-1429, 10.1175/1520-0485(2002)032<1404:Eotito>2.0.Co;2.
Title: Effects of the Indonesian Throughflow on the Pacific and Indian oceans
Type: Journal Article
Publication: Journal of Physical Oceanography
Author(s): Lee, T; Fukumori, I; Menemenlis, Dimitris; Xing, Z F; Fu, L L
Year: 2002
Formatted Citation: Lee, T., I. Fukumori, D. Menemenlis, Z. F. Xing, and L. L. Fu, 2002: Effects of the Indonesian Throughflow on the Pacific and Indian oceans. Journal of Physical Oceanography, 32(5), 1404-1429, doi:10.1175/1520-0485(2002)032<1404:Eotito>2.0.Co;2
Abstract: Effects of the Indonesian Throughflow (ITF) on the circulation and thermal structure of the Pacific and Indian Oceans are studied by comparing solutions of a near-global ocean general circulation model with open and closed Indonesian passages from 1981 to 1997. The ITF contributes to the maintenance of the model circulation system around eastern Australia and the southern Indian Ocean. Blockage of the ITF weakens the Indian Ocean South Equatorial Current and Agulhas Current and strengthens the East Australian Current. The ITF does not affect the Mindanao Current, but drains waters carried by this current into the Indian Ocean and thus reduces tropical-subtropical exchange in the North Pacific. Meanwhile, it helps maintain a stronger New Guinea Coastal Undercurrent and thus enhances tropical-subtropical exchange in the south. Water parcels traveling along the western boundary of the South Pacific cross the equator in the presence of the ITF but are confined to the Southern Hemisphere without the ITF. The southern "exchange window'' in which subducted waters can reach the Tropics is wider with than without the ITF. Some parcels from the southern subtropics can reach the Tropics with open ITF, but recirculate back to the subtropical gyre when the ITF is closed. These "excess'' recirculated parcels reach several degrees farther south and outcrop north of Tasmania. The consequence on sea surface temperature (SST) there may have an important implication to the local climate. Blockage of the ITF depresses the mean thermocline of the tropical Pacific, increases SST in the central to eastern equatorial Pacific, and thus reduces the SST difference between the warm pool and cold tongue. It also raises the mean thermocline of the Indian Ocean (especially the southern Indian Ocean) and decreases SST in the southern Indian Ocean. Blockage of the ITF reduces seasonal-to-interannual thermocline fluctuations in the central to eastern equatorial Pacific because the resulting deeper thermocline attenuates fluctuations in response to local Ekman pumping. The opposite is true in the southern Indian Ocean for the interannual timescale. However, seasonal thermocline fluctuation in that area is weakened when the ITF is blocked (despite a shallower thermocline). It indicates that local Ekman pumping is not the dominant mechanism controlling seasonal thermocline variability there as previously suggested. Radiation of planetary waves from the ITF area and advection by the ITF-dependent South Equatorial Current could also be important. Blockage of the ITF also reduces interannual variability of SST in the eastern equatorial Pacific and enhances those in the tropical southern Indian Ocean and south of Tasmania. The results indicate that the ITF may affect El Nino-Southern Oscillation by modifying tropical-subtropical exchanges, mean tropical thermocline structure, mean SST difference between the warm pool and cold tongue, and seasonal-to-interannual variabilities of thermocline depth and SST.
Keywords: appearance reality, climatology, el-nino, exchange, general-circulation model, north pacific, originate, parameterization, thermocline, water
ECCO Products Used: ECCO-KFS
URL:
Other URLs:
Lee, Tong; Fukumori, Ichiro; Menemenlis, Dimitris; Fu, Lee-Lueng (2002). Upper-ocean Heat Budget Inferred From ECCO-2 Ocean Data Assimilation, 2002 International Symposium En Route to GODAE, 2.
Title: Upper-ocean Heat Budget Inferred From ECCO-2 Ocean Data Assimilation
Type: Conference Proceedings
Publication: 2002 International Symposium En Route to GODAE
Author(s): Lee, Tong; Fukumori, Ichiro; Menemenlis, Dimitris; Fu, Lee-Lueng
Year: 2002
Formatted Citation: Lee, T., I. Fukumori, D. Menemenlis, and L. Fu, 2002: Upper-ocean Heat Budget Inferred From ECCO-2 Ocean Data Assimilation. 2002 International Symposium En Route to GODAE, Biarritz, France, 2 pp.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: http://hdl.handle.net/2014/8786
McKinley, Galen Anile (2002). Interannual variability of air-sea fluxes of carbon dioxide and oxygen.
Title: Interannual variability of air-sea fluxes of carbon dioxide and oxygen
Type: Thesis
Publication:
Author(s): McKinley, Galen Anile
Year: 2002
Formatted Citation: McKinley, G. A., 2002: Interannual variability of air-sea fluxes of carbon dioxide and oxygen., 169 pp.
Abstract: The currently observed increase in atmospheric CO 2 due anthropogenic emissions is sub- stantially slowed by natural processes that incorporate CO 2 into the terrestrial biota and the ocean. Year-to-year changes in the CO 2 growth rate that exceed variations in the fossil fuel source indicate a significant variability in these global CO 2 sinks. However, the enormous complexity of the terrestrial and oceanic biogeochemical systems that absorb atmospheric CO 2 makes these sinks extremely difficult to understand and precisely quantify. Many techniques, including the interpretation of the relative changes in atmospheric CO 2 and O 2 /N 2 , ocean modeling, and atmospheric data inversions, have been employed to estimate the mean and variability of global CO 2 sinks. However, uncertainty remains large. The goal of this thesis is to improve understanding of global CO 2 sinks by considering (1) the error in the atmospheric O 2 /N 2 partitioning method due to the neglect of interannual variability in the air-sea fluxes of O 2 , and (2) the interannual variability of the ocean CO 2 sink. A global, high-resolution ocean general circulation model is used to estimate the magnitude and understand the mechanisms of interannual variability in air-sea fluxes of both CO 2 and O 2 . I find that the global variability in the fluxes of both gases are dominantly forced by large-scale physical processes governing upper ocean dynamics, particularly El Niño / Southern Oscillation (ENSO) and, for O 2 , the North Atlantic Oscillation (NAO). Estimates of the extremes of CO 2 and O 2 flux variability for the period 1980-1998 are ±0.5x10 15 grams Carbon/yr (PgC/yr) and -70/+100x10 12 mol/yr (Tmol/yr), respectively. Global O 2 flux variability implies up to a 1.0 PgC/yr error in estimates of interannual variability in land and ocean CO 2 sinks derived from atmospheric O 2 /N 2 observations. This error is significant for estimates of annual sinks, but it is cumulatively negligible for estimates of mean sinks from October 1991 to April 1998. Increasing convergence of estimates of land and ocean carbon sink variability from independent methods is also found.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: https://dspace.mit.edu/bitstream/handle/1721.1/16824/51042777-MIT.pdf?sequence=2
Fukumori, I (2002). A partitioned Kalman filter and smoother, Monthly Weather Review, 5 (130), 1370-1383, 10.1175/1520-0493(2002)130<1370:Apkfas>2.0.Co;2.
Title: A partitioned Kalman filter and smoother
Type: Journal Article
Publication: Monthly Weather Review
Author(s): Fukumori, I
Year: 2002
Formatted Citation: Fukumori, I., 2002: A partitioned Kalman filter and smoother. Monthly Weather Review, 130(5), 1370-1383, doi:10.1175/1520-0493(2002)130<1370:Apkfas>2.0.Co;2
Abstract: A new approach is advanced for approximating Kalman filtering and smoothing suitable for oceanic and atmospheric data assimilation. The method solves the larger estimation problem by partitioning it into a series of smaller calculations. Errors with small correlation distances are derived by regional approximations, and errors associated with independent processes are evaluated separately from one another. The overall uncertainty of the model state, as well as the Kalman filter and smoother, is approximated by the sum of the corresponding individual components. The resulting smaller dimensionality of each separate element renders application of Kalman filtering and smoothing to the larger problem much more practical than otherwise. In particular, the approximation makes high-resolution global eddy-resolving data assimilation computationally viable. The approach is described and its efficacy demonstrated using a simple one-dimensional shallow water model.
Keywords: data assimilation, el-nino, nino-southern oscillation, ocean circulation model, oceanography, sea-level, topex/poseidon, tropical pacific-ocean
ECCO Products Used: ECCO-KFS
URL:
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Dickey, J O; Marcus, S L; de Viron, O; Fukumori, I (2002). Recent Earth oblateness variations: Unraveling climate and postglacial rebound effects, Science, 5600 (298), 1975-1977, 10.1126/Science.1077777.
Title: Recent Earth oblateness variations: Unraveling climate and postglacial rebound effects
Type: Journal Article
Publication: Science
Author(s): Dickey, J O; Marcus, S L; de Viron, O; Fukumori, I
Year: 2002
Formatted Citation: Dickey, J. O., S. L. Marcus, O. de Viron, and I. Fukumori, 2002: Recent Earth oblateness variations: Unraveling climate and postglacial rebound effects. Science, 298(5600), 1975-1977, doi:10.1126/Science.1077777
Abstract: Earth's dynamic oblateness (J(2)) has been decreasing due to postglacial rebound (PGR). However, J(2) began to increase in 1997, indicating a pronounced global-scale mass redistribution within Earth's system. We have determined that the observed increases in J(2) are caused primarily by a recent surge in subpolar glacial melting and by mass shifts in the Southern, Pacific, and Indian oceans. When these effects are removed, the residual trend in J(2) (-2.9 x 10(-11) year(-1)) becomes consistent with previous estimates of PGR from satellite and eclipse data. The climatic significance of these rapid shifts in glacial and oceanic mass, however, remains to be investigated.
Keywords: glaciers, reanalysis, rotation
ECCO Products Used: ECCO-KFS
URL:
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Wang, Shizhen (2002). Sea Level Change and Crustal Motion around Taiwan Observed by Satellite Altimetry and Tide Gauge.
Title: Sea Level Change and Crustal Motion around Taiwan Observed by Satellite Altimetry and Tide Gauge
Type: Thesis
Publication:
Author(s): Wang, Shizhen
Year: 2002
Formatted Citation: Wang, S., 2002: Sea Level Change and Crustal Motion around Taiwan Observed by Satellite Altimetry and Tide Gauge., 113 pp. doi:10.6844/NCKU.2013.00281.
Abstract: Taiwan is an island, where most of mountains located at the central area, and most highly developed cities are located near the coasts. Compared with other countries, sea level rise could cause a relative significant impact on Taiwan. In addition, resulting from the over-withdrawal of groundwater, the western area of Taiwan suffers from a severe subsidence. Therefore, monitoring sea level variations and vertical motions have become a very important issue for Taiwan. Traditionally, the most common instruments used to measure sea surface heights tide gauges and satellite altimetry; however, the tide gauge records contain the crustal vertical motions and the data span of satellite altimetry data is too short to avoid low-frequency effects on the trend determination. Since tide gauge records contain sea level and vertical motion signals and altimetry data contains sea level information only, vertical motions at gauges can be accurately computed by the differences of tide gauges and satellite altimetry. The estimated vertical motions show that most gauge stations in Taiwan and Philippines were subsiding except for in China. The vertical uplift in China is related to the geological tectonics and geomorphology. In order to determine sea level accurately around Taiwan, we adopted a novel algorithm to determine accurate sea level trend by combining tide gauges and satellite altimeter data in the study. First of all, Hilbert-Huang Transformation (HHT) method is used to decompose the selected tide gauge records completely into few independent monotones cycles, which called Intrinsic Mode Functions (IMFs). Afterwards, the residual time series computed by subtracting sea level time series reconstructed using specific IMFs, which represent low frequencies and cannot be clearly detected in altimeter data, from the corresponding altimetry data is fitted to derive the sea level trend. According to the result, the estimated sea level trend around Taiwan is 4.23 mm/yr, which is higher than global mean sea level of 3.11 mm/yr [Ablain et al., 2009]. A comparison of steric sea level (SSL), GRACE derived ocean mass change and total sea level around Taiwan is also investigated in the study. The result indicates that SSL contributes more than ocean mass does and dominates sea level trends around Taiwan. Finally, the global sea level trend derived from the reconstructed latitude-weighted time series using the last two IMFs by HHT is determined at 3.12 mm/yr, agreeing well with previous studies.
Keywords: Crustal motion, HHT, Satellite altimetry, Sea level change, Tide gauge
ECCO Products Used: ECCO-KFS
Other URLs: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0026-0502201301312300
Menemenlis, Dimitris; Fu, Lee-Lueng; Lee, Tong; Fukumori, Ichiro (2002). Calibrating the ECCO ocean general circulation model using Green’s functions, 2002 International Symposium En Route to GODAE, 2.
Title: Calibrating the ECCO ocean general circulation model using Green’s functions
Type: Conference Proceedings
Publication: 2002 International Symposium En Route to GODAE
Author(s): Menemenlis, Dimitris; Fu, Lee-Lueng; Lee, Tong; Fukumori, Ichiro
Year: 2002
Formatted Citation: Menemenlis, D., L. Fu, T. Lee, and I. Fukumori, 2002: Calibrating the ECCO ocean general circulation model using Green's functions. 2002 International Symposium En Route to GODAE, Biarritz, France, 2 pp. http://hdl.handle.net/2014/8710.
Abstract: Green's functions provide a simple, yet effective, method to test and calibrate General-Circulation-Model(GCM) parameterizations, to study and quantify model and data errors, to correct model biases and trends, and to blend estimates from different solutions and data products.
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs:
Schröter, Jens; Fukumori, Ichiro; Stammer, Detlef; Wenzel, Manfred; Wolf-Gladrow, Dieter (2002). Research and climate applications, Proceedings "En route to GODAE".
Title: Research and climate applications
Type: Conference Proceedings
Publication: Proceedings "En route to GODAE"
Author(s): Schröter, Jens; Fukumori, Ichiro; Stammer, Detlef; Wenzel, Manfred; Wolf-Gladrow, Dieter
Year: 2002
Formatted Citation: Schröter, J., I. Fukumori, D. Stammer, M. Wenzel, and D. Wolf-Gladrow, 2002: Research and climate applications. Proceedings "En route to GODAE" http://epic.awi.de/5690/1/Sch2002q.pdf.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0
Other URLs:
Stammer, D.; Wunsch, C.; Fukumori, I.; Marshall, J. (2001). State Estimation In Modern Oceanographic Research.
Title: State Estimation In Modern Oceanographic Research
Type: Report
Publication:
Author(s): Stammer, D.; Wunsch, C.; Fukumori, I.; Marshall, J.
Year: 2001
Formatted Citation: Stammer, D., C. Wunsch, I. Fukumori, and J. Marshall, 2001: State Estimation In Modern Oceanographic Research., 18 pp. http://www.ecco-group.org/ecco1/report/report_14.pdf.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0
Other URLs:
Fukumori, I.; Lee, T.; Menemenlis, Dimitris; Fu, L.; Cheng, B.; Tang, B.; Xing, Z.; Giering, R. (2001). Towards operational ocean state estimation, Fifth Symposium on Integrated Observing Systems, 4.
Title: Towards operational ocean state estimation
Type: Conference Proceedings
Publication: Fifth Symposium on Integrated Observing Systems
Author(s): Fukumori, I.; Lee, T.; Menemenlis, Dimitris; Fu, L.; Cheng, B.; Tang, B.; Xing, Z.; Giering, R.
Year: 2001
Formatted Citation: Fukumori, I., T. Lee, D. Menemenlis, L. Fu, B. Cheng, B. Tang, Z. Xing, and R. Giering, 2001: Towards operational ocean state estimation. Fifth Symposium on Integrated Observing Systems, Alburquerque, New Mexico, 4 pp.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS
Other URLs: https://trs.jpl.nasa.gov/handle/2014/16207
Stammer, D.; Davis, R.; Fu, L.-L.; Fukumori, I.; Giering, R.; Lee, T.; Marotzke, J.; Marshall, J.; Menemenlis, Dimitris; Niiler, P.; Wunsch, C.; Zlotnicki, V. (2000). Ocean state estimation in support of CLIVAR and GODAE, CLIVAR Exchanges, 3 (5), 3-5.
Title: Ocean state estimation in support of CLIVAR and GODAE
Type: Magazine Article
Publication: CLIVAR Exchanges
Author(s): Stammer, D.; Davis, R.; Fu, L.-L.; Fukumori, I.; Giering, R.; Lee, T.; Marotzke, J.; Marshall, J.; Menemenlis, Dimitris; Niiler, P.; Wunsch, C.; Zlotnicki, V.
Year: 2000
Formatted Citation: Stammer, D. and Coauthors, 2000: Ocean state estimation in support of CLIVAR and GODAE. CLIVAR Exchanges, 5(3), 3-5 pp. http://puddle.mit.edu/~mick/manuscripts.html.
Abstract:
Keywords:
ECCO Products Used: ECCO-KFS;ECCO-V0
Other URLs:
Fukumori, I; Raghunath, R; Fu, L L; Chao, Y (1999). Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results?, Journal of Geophysical Research-Oceans, C11 (104), 25647-25665, 10.1029/1999jc900193.
Title: Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results?
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Fukumori, I; Raghunath, R; Fu, L L; Chao, Y
Year: 1999
Formatted Citation: Fukumori, I., R. Raghunath, L. L. Fu, and Y. Chao, 1999: Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results? J. Geophys. Res. Ocean., 104(C11), 25647-25665, doi:10.1029/1999jc900193
Abstract: The feasibility of assimilating satellite altimetry data into a global ocean general circulation model is studied. Three years of TOPEX/Poseidon data are analyzed using a global, three-dimensional, nonlinear primitive equation model. The assimilation's success is examined by analyzing its consistency and reliability measured by formal error estimates with respect to independent measurements. Improvements in model solution are demonstrated, in particular, properties not directly measured. Comparisons are performed with sea level measured by tide gauges, subsurface temperatures and currents from moorings, and bottom pressure measurements. Model representation errors dictate what can and cannot be resolved by assimilation, and its identification is emphasized.
Keywords: gulf-stream model, height, kalman filter, sea-surface, tropical pacific-ocean, variability, wind-stress
ECCO Products Used: ECCO-KFS
URL:
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Fukumori, I; Raghunath, R; Fu, L L (1998). Nature of global large-scale sea level variability in relation to atmospheric forcing: A modeling study, Journal of Geophysical Research-Oceans, C3 (103), 5493-5512, 10.1029/97jc02907.
Title: Nature of global large-scale sea level variability in relation to atmospheric forcing: A modeling study
Type: Journal Article
Publication: Journal of Geophysical Research-Oceans
Author(s): Fukumori, I; Raghunath, R; Fu, L L
Year: 1998
Formatted Citation: Fukumori, I., R. Raghunath, and L. L. Fu, 1998: Nature of global large-scale sea level variability in relation to atmospheric forcing: A modeling study. J. Geophys. Res. Ocean., 103(C3), 5493-5512, doi:10.1029/97jc02907
Abstract: The relation between large-scale sea level variability and ocean circulation is studied using a numerical model. A global primitive equation model of the ocean is forced by daily winds and climatological heat fluxes corresponding to the period from January 1992 to January 1994. The physical nature of sea level's temporal variability from periods of days to a year is examined on the basis of spectral analyses of model results and comparisons with satellite altimetry and tide gauge measurements. The study elucidates and diagnoses the inhomogeneous physics of sea level change in space and frequency domain. At midlatitudes, large-scale sea level variability is primarily due to steric changes associated with the seasonal heating and cooling cycle of the surface layer. In comparison, changes in the tropics and high latitudes are mainly wind driven. Wind-driven variability exhibits a strong latitudinal dependence in itself. Wind-driven changes are largely baroclinic in the tropics but barotropic at higher latitudes. Baroclinic changes are dominated by the annual harmonic of the first baroclinic mode and is largest off the equator; variabilities associated with equatorial waves are smaller in comparison. Wind-driven barotropic changes exhibit a notable enhancement over several abyssal plains in the Southern Ocean, which is likely due to resonant planetary wave modes in basins semienclosed by discontinuities in potential vorticity. Otherwise, barotropic sea level changes are typically dominated by high frequencies with as much as half the total variance in periods shorter than 20 days, reflecting the frequency spectra of wind stress curl. Implications of the findings with regards to analyzing observations and data assimilation are discussed.
Keywords: data assimilation, fluctuations, general-circulation model, ocean circulation, pacific-ocean, satellite altimetry, surface, wind-stress, world ocean
ECCO Products Used: ECCO-KFS
URL:
Other URLs: