Arctic Ocean: mixing and exchange in a changing ocean

The Arctic Ocean differs from other oceans globally in several ways. Stratification is largely determined by changes in salinity, with cooler fresher water overlying warmer (intruding) saltier water. Until very recently the ocean was largely isolated from the atmosphere by sea ice restricting exchange of heat and momentum across the sea surface. As much of the Arctic Ocean lies poleward of the critical latitude for the dominant tidal forcing, preventing the formation of freely propagating internal tides, the major pathway of tidal energy to ocean mixing. As such mixing between layers in the Arctic Ocean is weak.

An analogy is often drawn between the circulation in the Arctic Ocean and that in an estuary. Lateral gradients in density drive exchange through Arctic gateways with the exchange flow mediated by vertical mixing within the Arctic Ocean. Here we examine the potential impact of the recent decline sea ice extent on both the vertical mixing and the import of heat and export of freshwater through the Arctic gateways.