1387 / 2019-08-10 00:02:25

Recent change in SAMW and its impact on the Southern Ocean warming

15、冰冻圈科学 > 专题6：海-冰-气相互作用的物理过程和机制

Argo float profiles reveal a trend towards increasing thickness, mean depth, volume and heat content of the SAMW south of 30°S between 2005 and 2015. The close correspondence between the pattern of change in SAMW thickness and depth and the pattern of change in wind stress curl suggests these observed trends are largely wind-driven. Enhanced Ekman pumping depressed the pycnocline, resulting in positive SSH anomalies over much of the southern hemisphere oceans south of 30°S. Changes in depth and thickness of the SAMW layer can explain more than half of the overall change in SSH. Our results demonstrate that wind-driven thickening and deepening of the SAMW accounts for 65% (56%) of the observed trends in 0-2000m heat content and SSH respectively. Buoyancy forcing accounts for only 16% of the heat gained by the SAMW layer, but is important as a net transfer of heat from the atmosphere to the ocean. Model projections suggest the westerly winds will continue to increase in the future, resulting in stronger wind stress curl.