报告题目：Impacts of Arctic Sea Ice on Atlantic and Pacific Climate

报告专家：Prof. Aiguo Dai（戴爱国 教授）

报告时间：2024年6月25日（周二）上午10:00

报告地点：气象楼423会议室

主  持 人：华文剑 教授

专家简介：

Dr. Dai is a Distinguished Professor of the Department of Atmospheric & Environmental Sciences at the University at Albany, State University of New York, USA. Dr. Dai obtained his PhD in Atmospheric Science from Columbia University in 1996. From 1997-2012, he worked at NCAR. In 2012, he joined the faculty of the University at Albany. He is an internationally renowned climate scientist with a focus on climate variability and change, Arctic climate, the global water cycle, hydroclimate, drought, the diurnal cycle, and climate data analysis. With more than 200 peer-reviewed publications, he has received 63,000-plus citations with an H-index of 91. He is one of the world’s top 1% Highly Cited Researchers. He served as the Chair of the Climate Variability and Change Committee and Editor of the Journal of Climate of the American Meteorological Society (AMS), and he is an AMS Fellow. He is currently working on the causes and impacts of Arctic rapid warming and sea-ice loss; changes in atmospheric thermodynamic conditions under global warming; the role of internal variability and external forcing in historical climate changes; and historical and future changes in precipitation, drought, and other hydroclimate fields.

报告摘要：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.

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2024.6.12