The Role of the Russian Shelf in Seasonal and Interannual Variability of Arctic Sea Surface Salinity and Freshwater Content

Abstract

AbstractFresh water plays a pivotal role in the Arctic Ocean's climate, as salinity governs upper ocean stratification, convection, and the promotion of seasonal sea ice growth or melt. The Beaufort Gyre (BG) contains a significant amount of fresh water; however, there is limited understanding of the role that the Russian Arctic Shelf plays in the Arctic Ocean's freshwater content (FWC). Here, we use salinity from the European Centre for Medium‐Range Weather Forecasts' Ocean Reanalysis System 5 product to first compare with in situ and satellite observations. We then conduct analyses over the years 1979–2018 to examine FWC and salinity on the Russian Shelf (30°E−180°E; shallower than 200 m depth), in the BG (130°W–170°W, 70.5°N–80.5°N), and over the Arctic Ocean as a whole (northward of 66°N). Our results indicate that the Russian Shelf consists of ∼16% of the total freshwater volume (FWV) in the Arctic Ocean (80,7623 km3) and has a negative trend (−15.63 km3/yr), primarily influenced by negative trends in the Kara and Laptev Seas. We also find a notable regime shift during the summer of 2007 for both the BG (increased FWV) and Russian Shelf (decreased FWV). When computing Arctic FWV changes before and after this 2007 regime shift, there is up to a 25% error if the Russian Shelf's FWV is omitted.