Snow accumulation has decreased significantly due to increased air temperatures and shifts in precipitation patterns resulting from climate change in cold regions worldwide. The presence or absence of snow cover has a significant impact on soil thermal conditions and the exchange of heat between the ground and the atmosphere. A snow-free break (SFB) refers to a period during which snow cover is absent, which can have significant impacts on soil temperature. In this study, we investigated the climatology of snow-free conditions (total period of SFB days, referred to hereafter as TPSFB) during the cold season based on meteorological station data across northern Eurasia from 1966 through 2019, and evaluated the potential combined impacts of meteorology, snow cover, and TPSFB on soil thermal regimes using structural equation models. It is found that the longer annual means of TPSFB were distributed in the western and southern Russian Plain, with a duration of >40 days, and the highest ratio of TPSFB to snow cover period reached up to 80.6 %. The long-term trend of TPSFB presented an evident east-west distribution difference, with 70°E serving as a boundary. The TPSFB decreased in most areas east of 70°E, while it increased significantly in the west, resulting from changes in air temperature and snow accumulation. The factors influencing soil thermal status differed on either side of 70°E. Increased air temperature was the dominant control, accelerating snowmelt and increasing TPSFB in the west of 70°E. However, the impacts of snow properties on soil temperatures were more significant in the eastern regions (e.g., the Siberian region) than in the west (e.g., the European Plain). These results indicate that, under climate warming, ground-atmosphere heat exchange varies significantly across regions depending on meteorological and snow cover conditions, potentially influencing ecosystem dynamics such as permafrost stability and soil carbon changes.

https://www.sciencedirect.com/science/article/pii/S016819232500348X