Variability of the Beaufort Gyre freshwater content in 2003-2018 from observations and model results

Hydrographic data collected from research cruises, moorings, Ice-Tethered Profiler observations and satellite altimetry in the Beaufort Gyre document an increase of more than 6,400 cubic km of liquid freshwater content from 2003-2018, a 40% growth relative to the climatology of the 1970s. This freshwater accumulation was a result of persistent anticyclonic atmospheric wind forcing accompanied by sea ice melt, wind-forced redirection of Mackenzie River discharge, and a contribution of waters of Pacific Ocean origin via Bering Strait. The fresh water input to the Beaufort Gyre region from Siberian rivers in 2003-2018 was negligible. Remnants of Siberian river waters detected by geochemical analysis, presumably penetrated into the region in 1989-1996 during a cyclonic circulation regime. A slight decrease of freshwater content in the region between 2010 and 2013 was associated with a relaxation of anticyclonic winds; however, in 2015-2016, the volume of freshwater content was greater than ever measured previously due to the combination of reintensified anticyclonic winds and continued fresh water supply from both ice melt and North American rivers discharge. In 2017 and 2018, the freshwater content remained high due to a complex variability of winds resulting in forcing favorable for freshwater content stabilization.