Possible influence of weakened autumn East Asian trough on winter Barents–Kara Seas warming

Abstract Winter warming over the Barents–Kara Seas (BKS) has received extensive attention over the past two decades because it is closely associated with Arctic sea ice loss, winter Eurasian cooling, and extreme cold events over East Asia. However, the role of mid-latitude atmospheric circulation anomalies in resulting winter BKS warming is unclear. This study investigates the relationship between autumn (October–November) East Asian trough (EAT) and the BKS warming in the subsequent winter (December–February) for the period 1979–2022. The result shows that when the autumn EAT weakens, warming, increased moisture, and sea ice loss are observed in the BKS during winter. The weakened EAT promotes increased sea surface temperatures (SSTs) in the mid-latitude North Pacific through increasing solar radiation and reducing cold air activity and positive SST anomalies persist into winter. These continuous warm SSTs from autumn to winter trigger winter Rossby waves downstream, which favors the occurrence of a combination of a positive phase of the North Atlantic Oscillation and high pressure over the Ural region, further leading to BKS warming.