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

高纬度的深水形成(对流)，更具体地说是北大西洋亚极地的拉布拉多海，构成了大规模海洋环流的关键部分。这使得大气和深海之间的气体交换成为可能，从而促进了全球海洋对碳的封存。在气候变暖的情况下，随着格陵兰冰盖和北冰洋冰川融化的增加，流入拉布拉多海的淡水增加，预计将减少或关闭对流，这将降低海洋缓解气候变化的潜力。在西部拉布拉多海，淡水在盆地边界和内陆之间交换，部分原因是小规模(亚中尺度&10公里)的过程。最近的证据表明，涡旋、海冰和大气(风和浮力)的强迫都可以影响这些小范围的过程。然而，由于极端的冬季条件，在拉布拉多海进行高分辨率观测的情况很少。因此，负责停止对流的机制仍然知之甚少，并且在很大程度上被气候模型忽视。本项目将使用自主平台(滑翔机)的多年测量来调查小范围过程在停止对流方面的作用。学生将确定涡旋、大气强迫和海冰对对流生命周期的竞争影响。

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.