Deep oceanic convection: the outsized role of small-scale processes

Deep-water formation (convection) at high-latitudes, and more specifically in the Labrador Sea in the subpolar North Atlantic, forms a key part of the large-scale ocean circulation. This enables the exchange of gases between the atmosphere and deep ocean, and thus contributes to the global oceanic sequestration of carbon. In a warming climate, added volumes of freshwater into the Labrador Sea, associated with the increased melting of Greenland ice sheet and of Arctic sea-ice, are expected to reduce or shutdown convection, which would reduce the ocean's potential to mitigate climate change. In the western Labrador Sea, freshwater is exchanged between the basin boundary and interior due in part to small-scale (submesoscale <10 km) processes. Recent evidence revealed that eddies, sea-ice, and atmospheric (wind and buoyancy) forcing can all influence these small-scale processes. However, high-resolution observations in the Labrador Sea are scarce due to extreme winter conditions. Thus, the mechanisms responsible for the cessation of convection remain poorly understood and are largely neglected by climate models.

This project will use multi-year measurements from autonomous platforms (gliders) to investigate the role of small-scale processes on the cessation of convection. The student will determine the competing effects of eddies, atmospheric forcing, and sea-ice on the lifecycle of convection.