报告题目：Impacts of Arctic Sea Ice on Atlantic and Pacific Climate
单 位：University at Albany, State University of New York
邀 请 人：罗德海 研究员
时 间：2024年7月16日上午9:30
地 点：2号楼319会议室
摘要：
To fully understand the potential impacts of the shrinking Arctic sea ice, we need to better understand the various roles of Arctic sea ice plays in our climate. In this talk, I will focus on how Arctic sea ice-air two-way interactions amplify multidecadal variability in the North Atlantic but dampen El Niño-Southern Oscillation (ENSO) variability in the Pacific. Using CESM1 model simulations with and without the sea ice-air interactions and collaborated with observational data, we show that variations in cold-season sea ice concentrations (SIC) around Arctic marginal ice zones can significantly amplify multidecadal variations in surface latent and sensible fluxes from the Labrador Sea to the Nordic Seas, leading to larger variations in upper ocean density and deep water formation in these seas, thereby amplifying the amplitudes of Atlantic Multidecadal Oscillation (AMO) and the Atlantic meridional overturning circulation. In the Pacific sector, SIC variations from the Bering Sea to Okhotsk Sea (BOS) lead to increased absorption of solar radiation due to asymmetric albedo effects of SIC anomalies. This results in warming in the northern North Pacific Ocean, which excites an anomalous tropospheric Rossby wave propagating equatorward into the tropical Pacific to strengthen cross-equator winds and deepen the thermocline there. These mean changes dampen ENSO amplitude via weakened thermocline and zonal advective feedbacks. Thus, Arctic sea ice–air interactions affect both the mean state and variability in the tropical Pacific and imply increased ENSO amplitude but weakened AMO as Arctic sea ice and its interactions with the atmosphere diminish under global warming.