Eddy activity in the high-latitude Southern Ocean and its response to climate change

Eddy activity in the high-latitude Southern Ocean is linked to critical drivers of the global climate such as Antarctic Bottom Water (AABW) formation, seasonal sea ice cover, and shoreward heat transport. Yet, no comprehensive description of eddy activity poleward of the Antarctic Circumpolar Current (ACC) exists and the mesoscale processes in the region are missing from virtually all major projections of climate change. Using a high-resolution ocean model and cost-reducing simulation design, eddy activity in the high southern latitudes is characterized with unprecedented detail, including 3-dimensional spatial distribution and characteristics, unobstructed information beneath sea ice, and projections of future conditions after prolonged anthropogenic warming. A rich mesoscale field is detected, with eddy activity closely linked to large-scale circulation features like gyres and the Antarctic Slope Current. Eddy activity exhibits a strong seasonal cycle in which the presence of sea ice decreases the eddy population and increases the proportion of anticyclones. Anthropogenic warming is projected to increase the eddy population, particularly in winter. Projected impacts of climate change are regionally diverse; ACC eddy activity shifts poleward, Antarctic Slope Current eddy activity intensifies, and the seasonal cycle affecting the eddy population and rotational direction is reduced.