Declining snow depth in northwest Central Asia driven by atmospheric dynamics and thermodynamic warming

The relative roles of atmospheric circulation and thermodynamic warming in driving the rapid decline of winter snow depth (SD) in northwest Central Asia (CA) remain poorly quantified, despite their opposing influences on regional snow variability. Here, based on observational datasets with large-ensemble climate model simulations, dynamical adjustment reveals that circulation-driven processes account for SD accumulation of 0.22 mm per year ( p < 0.1) during 1979–2024, whereas thermodynamically driven warming overwhelms this effect, producing an SD shallowing of −1.00 mm per year ( p < 0.1). Among circulation influences, externally forced sea surface temperature (SST) anomalies explain 82% of the dynamical SD changes, with the remainder dominantly governed by internally generated SST anomalies. Both eastern Pacific cooling and North Atlantic warming induce northerly and easterly anomalies over northwest CA, enhancing cold advection and favoring snow accumulation. Moreover, winter SD exhibits a predictive influence on subsequent spring climate. These findings underscore the combined influence of dynamic and thermodynamic processes in shaping SD decline in northwest CA, providing insights for water resource management and regional climate adaptation.