Inter-Model Uncertainty in Projecting Precipitation Changes Over Central Asia Under Global Warming

Abstract

The impact of global warming on Central Asian precipitation suffers from huge uncertainties, yet their origins remain largely unidentified. This study investigates the inter-model spread in the projection of winter Central Asian precipitation (WCAP) using models from the Coupled Model Inter-comparison Project Phase 6. The results reveal a homogenous wetting trend in WCAP, with the primary source of uncertainty in its magnitude stemming from the dynamic component of vertical moisture advection. This dynamical uncertainty is further attributed to an out-of-phase variation between two Eurasian westerly jets, which can enhance the upward motion over Central Asia through positive relative vorticity advection and warm temperature advection. The opposing variation between two westerly jets can be traced to cooling in the North Pacific, which alters jet intensity through changes in the meridional temperature gradient. This study informs policy and adaptation strategies to better cope with future climate shifts in Central Asia.