Pronounced ocean thermal variability triggered by synoptic forcing in the Eastern Eurasian Arctic

Rapid Arctic warming has diminished sea-ice cover, increasing ocean exposure to synoptic atmospheric forcing. Here we examine how such forcing redistributes ocean heat across seasons in the evolving marginal ice zone of the eastern Eurasian Arctic using an ocean–ice coupled numerical model with a one-kilometer horizontal resolution in the Arctic. Synoptic atmospheric forcing produces pronounced, vertically structured temperature anomalies from the surface to the ocean interior, with their magnitude and timing shaped by seasonal sea-ice and stratification changes. During summer, increased surface heat flux over expanding areas of open water amplifies cooling of the ocean mixed layer under synoptic forcing. In winter, interior anomalies are sustained by vertical heat redistribution resulting from Ekman pumping and baroclinic instability during synoptic events. These results show that synoptic atmospheric forcing, together with seasonal changes in sea ice and stratification, shapes vertical heat redistribution and ocean thermal variability in the Arctic. Cyclonic and anticyclonic atmospheric synoptic forcings produce pronounced vertical structure in upper-ocean temperature anomalies in the eastern Eurasian Arctic, with their magnitude and timing shaped by the seasonal evolution of sea ice and stratification, as shown by experiments using a high-resolution ocean-ice coupled model.