Interannual responses of Arctic temperatures to Eurasian snow cover variations in early spring

Abstract

Variations in snow cover could have profound impacts on regional and large-scale circulations and climate anomalies. Previous studies have focused on their effects on mid- to low-latitude weather without considering the impacts on the Arctic climate. Here, we propose that the snow cover in Europe and Central Siberia is an important land factor for the early spring 2 m temperature (T2m) interannual variability in the Barents–Kara Sea (BKS). In years when there is less snow over Europe and Central Siberia, there are positive radiative forcing at the surface, which can lead to elevated surface air temperatures, contributing to upward surface sensible heat flux anomalies. Correspondingly, anomalous anticyclones appear in the mid-upper troposphere, accompanied by enhanced southwesterly winds over the northern side of Europe and southerly winds over the western side of Central Siberia, enhancing the transport of atmospheric heat and moisture to the BKS and their conservation. Such variations consequently increase the downwelling longwave radiation and T2m over the BKS. Moreover, the negative correlation between Eurasian SWE and BKS T2m can be identified by most CMIP6 models and by multi-model ensemble (MME) results. Additionally, the multidecadal fluctuations in the Eurasian SWE–Arctic T2m connection are strongly out of phase with the PDO index, which can be effectively captured in the CMIP6 MME results. Furthermore, among two different PDO- periods, the BKS T2m were influenced mainly by variation in SWE in Central Siberia during P1 (1962–1977) and, conversely, were impacted mainly by variation in SWE in Europe during P3 (1999–2012).