Causality in the Winter Interaction Between Extratropical Storm Tracks, Atmospheric Circulation, and Arctic Sea Ice Loss

Abstract

Global warming is accelerating the decline of Arctic sea ice, with wide-ranging impacts on the Earth's climate system. Using ERA5 data from 1980 to 2023, we investigated the relationship between winter extratropical storm tracks, atmospheric circulation patterns, and sea ice area (SIA) in three key Arctic regions. We classified the winters into two categories: atmosphere-driven winters (ADWs), when atmospheric circulation influences sea ice, and ice-driven winters (IDWs), when sea ice influences atmospheric circulation. This classification was based on the sign of SIA and surface turbulent heat flux anomalies in the Barents-Kara Sea (BKS), Baffin Bay, Davis Strait, and Labrador Sea (BDL), and Chukchi-Bering Seas (CBS). Our findings show that in IDWs, reduced SIA has a minor effect on extratropical storm tracks. However, we observed significant midtropospheric cooling over northeastern Asia, aligning with the effects of reduced ice in the BKS during IDWs. This emphasizes the importance of considering the entire tropospheric temperature profile to capture the impact of sea ice loss. In contrast, during ADWs, the BKS and CBS regions experience amplified surface warming and SIA loss due to storm-induced intrusion of warm and moist air, with sea ice loss in the BKS contributing to strengthening Ural blocking. Although cyclone-induced heat and moisture intrusion is prevalent, we found no significant trend in track density or mean intensity of positive V extrema in the North Atlantic sector of the Arctic, suggesting that changes in atmospheric circulation are unlikely to be the driver of recent sea ice loss in the BKS.