Local and Remote Drivers of Variability in Liquid Freshwater Transport through Denmark Strait

Abstract. The Arctic is a rapidly changing region, warming faster than the rest of the planet. The Arctic is also a source of freshwater, which is exported to the North Atlantic where it influences local and global circulation. Thus, rapid changes within the Arctic have important consequences for global climate, in part mediated by the processes that control the export of freshwater through the major straits. In this study we examine the surface controls on the monthly variance of liquid freshwater transport through Denmark Strait, one of the major gateways to the subpolar North Atlantic, in an ocean state estimate. We find that local wind variance along the east of Greenland from the previous four months explains over 70% of the variance in freshwater transport through Denmark Strait. However, Arctic wind variance from 1–4 years previously contributes roughly 10% of the explained variance of December and January freshwater transport. The seasonal nature of this relationship is linked to the local seasonal cycle in sea ice. The location of the largest contributions at multi-year timescales, the edge of the Beaufort Gyre, is proposed to be due to the coincidence of relatively high wind variance and the freshwater store in the gyre itself. These results demonstrate that, while local conditions are dominant in controlling monthly transport rate variance, conditions in the Arctic may play a stronger role as sea ice continues to decline, particularly in winter.