Anomalously fresh Chukchi Sea surface salinity in summer-autumn 2021

The Chukchi Sea is a marginal sea in the Arctic with a mixed layer that is a few psu units saltier than ambient open Arctic water. Such higher salinity is maintained by salty and warm Pacific water inflow through the Bering Strait, implying that changes in inflow characteristics should affect the thermohaline properties of the Chukchi Sea. Recently, two additional controlling factors have been highlighted - the strength of boundary currents along the Siberian coast, and meridional exchanges due to wind-driven transport. In this note, we illustrate that anomalous fresh Chukchi Sea surface salinity in summer-autumn 2021 may be related to the anomalous southward shift of the ice edge and its meltwater source. These anomalous ice conditions occur concurrently with anomalously low Beaufort High, anomalous westerly cyclonic winds over ice-covered and open water Chukchi Sea, and related southward Ekman transport of late season meltwater. The September 2021 ice expansion was the largest in 1981-2021 detrended ice records.

Automated summary

The thermohaline properties of the Chukchi Sea are affected by the influx of salty and warm Pacific water through the Bering Strait, as well as boundary currents and wind-driven transport. The anomalous southward shift of the ice edge and its meltwater source in summer-autumn 2021 led to an anomalous fresh Chukchi Sea surface salinity.