Impact of the Shrinkage of Arctic Sea Ice on Eurasian Snow Cover Changes in 1979–2021

Abstract

Recent research has shown that snow cover induces extreme wintertime cooling and has detrimental impacts. Although the dramatic loss of Arctic sea ice certainly has contributed to a more extreme climate, the mechanism connecting sea-ice loss to extensive snow cover is still up for debate. In this study, a significant relationship between sea ice concentration (SIC) in the Barents-Kara (B-K) seas in November and snow cover extent over Eurasia in winter (November–January) has been found based in observational datasets and through numerical experiments. The reduction in B-K sea ice gives rise to a negative phase of Arctic Oscillation (AO), a deepened East Asia trough, and a shallow trough over Europe. These circulation anomalies lead to colder-than-normal Eurasian mid-latitude temperatures, providing favorable conditions for snowfall. In addition, two prominent cyclonic anomalies near Europe and Lake Baikal affect moisture transport and its divergence, which results in increased precipitation due to moisture advection and wind convergence. Furthermore, anomalous E-P flux shows that amplified upward propagating waves associated with the low SIC could contribute to the weakening of the polar vortex and southward breakouts of cold air. This work may be helpful for further understanding and predicting the snowfall conditions in the middle latitudes.

摘要

**期研究表明积雪变化会导致冬季极端降温,并对人类的生产生活产生影响。北极海冰的急剧减少导致了中纬度极端气候,但海冰减少与欧亚大陆积雪之间的关系及其影响机制仍有待于进一步研究。本文基于观测数据和数值试验发现11月巴伦支海-喀拉海海冰与冬季(11-1月)欧亚大陆积雪范围之间有密切关系,具体表现为欧洲、中亚和东亚地区冬季积雪范围增大。伴随着海冰减少,北极涛动位于其负位相,同时东亚大槽和欧洲上空浅槽加深,这些环流异常导致来自极地的冷空气更容易向南爆发,造成欧亚大陆低温,为降雪提供了有利条件。此外,位于欧洲和贝加尔湖附**的两个气旋异常影响了水汽通量及其通量散度,水汽**流作用和风辐合作用导致欧亚大陆出现降雪的概率增大。此外,海冰减少产生向上的E-P通量,导致**流层极涡减弱,经向活动明显增**,中纬度地区变冷。从而11月巴伦支海-喀拉海海冰减少引起了欧亚大陆积雪范围变化。本研究为进一步理解和预测中纬度地区降雪提供了理论基础。