Decomposition of airflow over topography and its application to a topographic blizzard event in central Asia

To better understand the triggering mechanisms of extreme precipitation events in Central Asia due to complex terrain, a case study topographic blizzard that occurred Xinjiang Province on 30 November 2018 is conducted. The near-surface wind field decomposed into flow-around and flow-over components analyze dynamic thermodynamic effects flow around over topography Ili River valley northern slope Tianshan Mountains. results reveal dominant component transports water vapor causes moisture convergence. symmetric instability observed at lower level snowfall area attributed field, which leads advective transport generalized potential temperature changes vorticity, ultimately resulting instability. local variation stratified caused by divergence, specifically, advection vertical shear equivalent change thus promotes Moreover, divergence negatively correlated with amount certain extent, can provide reference for forecast future. Additionally, cyclonic vorticity mainly produces favorable vortical circulation conditions snowfall, while movement near ground stage component. Furthermore, kinetic energy snow stronger work done pressure gradient force terrain drives changes.