The Arctic–Subarctic Exchange Through Hudson Strait

One major export of (fresh) water from the Arctic region to the North Atlantic is due to surface-intensified currents that flow along the topographic margins. These enter the North Atlantic through three major straits – Fram, Davis and Hudson – which therefore provide ideal gateways for monitoring the exchange. Of these straits, the first two link the North Atlantic Ocean with the Arctic Ocean while the third, Hudson Strait, connects it to an extensive Arctic region, the Hudson Bay System (HBS), which, in its northwest corner, is also connected to the Arctic Ocean (via Fury and Hecla Strait – Fig. 10.1). The lack of a direct connection with the Arctic Ocean is, likely, the reason why Hudson Strait’s contribution to the Arctic/ North Atlantic exchange has, until recently, been overlooked. In this chapter, we present estimates for the net, as well as the inflow and outflow transports, of volume, heat and freshwater through Hudson Strait. These are based both on a review of the inputs into the basin and on the first year-long measurements of the outflow from Hudson Strait to the Labrador Sea. This analysis shows not only that the HBS provides a substantial net input of Arctic (fresh) water to the North Atlantic but, also, that a significant fraction of the export through Davis Strait is recirculated in the HBS before it effectively flows into the Labrador Sea.