Poleward shift of the North Pacific storm track driven by springtime East Asian dust heating

Abstract. The North Pacific storm track shapes precipitation and temperature patterns over the Arctic and western North America, yet how its sensitivity to springtime East Asian dust remains poorly understood. Based on the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data from 1980 to 2022, we find that anomalously high springtime East Asian dust loading is robustly associated with a systematic poleward shift of the North Pacific storm track on interannual timescales. The physical mechanism proceeds through a clear causal chain. In details, shortwave absorption by the trans-Pacific dust plume warms the mid-troposphere between 850 and 400 hPa, exciting an anomalous anticyclonic circulation over the North Pacific. This thermal perturbation restructures the meridional temperature gradient and shifts the zone of maximum Eady growth rate poleward, thereby relocating the preferred region for baroclinic eddy development to higher latitudes. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) sensitivity experiments reproduce both the spatial pattern and sign of the storm track response, confirming that dust shortwave absorption is sufficient to drive the observed displacement. These findings demonstrate that natural dust aerosols can modulate large-scale North Pacific atmospheric dynamics and suggest that springtime dust variability should be considered in regional climate assessments.