Amplification of East Asian Cold Extremes by Sudden Changes in Snow Cover

Substantial progress has been made in understanding the role of snow cover (SC) within the climate system. Previous studies have focused predominantly on average SC conditions across specific months or seasons. However, the atmospheric impacts of occasional SC, which last only a few days, have been largely overlooked. Here, we demonstrate that the sudden appearance of occasional SC in East Asia, despite its short duration, induces an immediate local cooling effect on the atmosphere, extending from the near surface to the lower troposphere. This cooling effect is driven by diabatic heating caused by the snow albedo effect. Numerical experiments indicate that 24% of the maximum intensity of extreme temperature drops associated with SC events is driven by SC amplification. Furthermore, in the absence of this feedback, the extremity of these temperature drops can be mitigated. This study underscores the critical role of occasional SC in shaping cold extremes and aims to highlight the need for greater attention to occasional SC phenomena in atmospheric research.