Impacts of Strengthened Antarctic Circumpolar Current on the Seasonality of Arctic Climate

To understand the role of the Antarctic Circumpolar Current (ACC) in the polar seasonality and its remote effect on the Arctic climate, we use the Community Earth System Model to perform Drake Passage (DP) open and closed experiments. Model results illustrate that in the opened DP, the ACC and Atlantic Meridional Overturning Circulation (AMOC) strengthen, leading to a colder Antarctic and a warmer Arctic. Notably, the temperature changes in both the Antarctic and the Arctic show significant seasonal differences, with the largest polar response during the cold seasons. Around the Antarctic, both the ACC and overturning circulation exhibit stronger acceleration in winter than in summer, causing more pronounced cooling in winter. Furthermore, negative seasonal energy transfer mechanism amplifies this cooling. In contrast, around the Arctic, the AMOC and ocean heat transport show relatively insignificant seasonal variation. Instead, it is the downward latent and sensible fluxes that induce amplified winter warming.