Meeting Documents

Group for High Resolution Sea Surface Temperature's 0.09 degree, level 4, globally gridded dataset (GHRSST-MWIR) comparison to the Arctic Great Rivers Observatory (Ar-GRO) Yukon River volumetric discharge dataset in the Gulf of Alaska from 2003-2020, and modelling outputs from the 'Estimating the State and Climate of the Ocean (ECCO)' model.

Abstract

In this study, we illustrate the versatility of the Group for High Resolution Sea Surface Temperature 0.09 degree, level 4, globally gridded microwave and infrared product (GHRSST-MWIR). Results indicate Yukon river warming, variations in conditions for fisheries, and more. We compare the SST dataset with the Arctic Great Rivers Observatory (Ar-GRO) Yukon River volumetric discharge dataset in the Gulf of Alaska and the Bering sea. We not only find a decadal scale pattern in the river discharge volume that is comparable to August SST anomalies from 2003–2020, but comparison of the Ar-GRO dataset with SST from the ‘Estimating the State and Climate of the Ocean (ECCO)’ model illustrates the usefulness of inverse modeling techniques to extend studies with limited-length datasets. (The GHRSST-MWIR dataset only extends to summer, 2002, whereas the ECCO model output fields reach back ten more years to 1992.)

Other datasets including MERRA-2 reanalysis fields of air temperature, and salinity fields from an ECCO model experiment indicate a relationship between the atmosphere and SST at the river mouth; SST closely follows August air temperature from 2003-2017. Rainfall and salinity at the river mouth alternate in relative magnitude by year, with the exception of 2010-2014 during a late summer cool SST anomaly in the Norton Sound when salinity remains relatively low, rainfall remains high. Maximum river discharge events may have occurred during years with high water vapor during the late summer at the river mouth. Years with high SST, and high rainfall in the late summer may have also promoted high river discharge events.

Future experiments will include comparing river discharge with a Yukon headwaters temperature dataset; headwater temperature from 2012-2020 is similar, but cooler by ~2 °C than river temperature. The VonFinster dataset (since 2012) revealed that when headwater temperature was ~6-8 °C, a greater volume of discharge occurred in late fall in 2015, 2016, 2018, and 2019, when the headwaters is approximately 1/2 of its maximum summer temperature. We plan to compare MERRA-2 air temperature to river discharge volume extended to 1992, to explore the possible causes of extreme river discharge events. Additional work will focus on satellite derived remote sensing data.