Mapping distribution and evolution of snow climate in High Mountain Asia during 1980–2018

Snow avalanches pose a growing hazard in High Mountain Asia (HMA), yet their regional patterns are strongly governed by snow-climate regimes that are sensitive to both long-term warming and large-scale circulation variability. Using reanalysis-based meteorological and snow datasets (1980–2018), we develop a spatially continuous snow-climate zonation for HMA and classify the region into maritime (11.9%), transitional (4.1%), and continental (73.0%) snow-climate regimes. We detect a systematic shift toward warmer and wetter snow-climate characteristics, with the most pronounced changes along the southeastern HMA, where the transitional regime expands markedly. Variance decomposition further reveals non-stationary controls on zonation variability: temperature dominates temporal variability in the maritime and transitional regimes (explaining ~80% of their variance), whereas the continental regime is jointly regulated by temperature and snowfall, with a substantial contribution from the North Atlantic Oscillation (NAO) through its dynamical modulation of circulation and moisture transport. These findings provide a mechanistic, regime-aware framework for stratified avalanche-susceptibility modeling and for differentiated monitoring and risk management strategies across HMA under continued climate warming.