Comparison of Freshwater Content and Variability in the Arctic Ocean Using Observations and Model Simulations

Freshwater content (FWC), generally characterized in the Arctic Ocean by salinities lower than 34.8 psu, has shifted in both quantity and distribution in recent decades in the Arctic Ocean. This has been largely driven by changes in the volume and salinity of freshwater sources and the direction and magnitude of major currents. In this study, we analyze the variability in FWC and other physical oceanographic variables from 1993 to 2021 in the Arctic Ocean and Beaufort Gyre (BG) using in situ and remote sensing observations and five ocean models and reanalysis products. Generally, ocean models and reanalysis products underestimate FWC in the BG when compared with observations. Modeled FWC and sea surface height (SSH) in the BG are well correlated during the time period and are similar to correlations of the observational data of these variables. ORAS5 compares best to EN4 salinity over the entire study period, although GLORYS12 agrees well pre-2007 and SODA post-2007. Outside the BG, consistency between modeled SSH, FWC, and limited observations varies between models. These comparisons help identify discrepancies in ocean model and reanalysis products while highlighting areas where future improvements are necessary to further our understanding of Arctic FWC. As observations are scarce in the Arctic, these products and their accuracy are important to studying this dynamic and vulnerable ocean.

Automated summary

Freshwater content (FWC) in the Arctic Ocean has changed in quantity and distribution, driven by changes in freshwater sources and major currents. This study analyzed FWC variability from 1993 to 2021 using observations, ocean models, and reanalysis products. Models underestimated FWC in the Beaufort Gyre, but correlated well with observations. ORAS5 showed the best agreement with salinity data. Comparisons between models and observations identified discrepancies and highlighted areas for improvement in understanding Arctic FWC. These products are crucial for studying the dynamic and vulnerable Arctic Ocean.