Impacts of anthropogenic aerosols on a snowfall event – a case study in the Guanzhong Basin and its surrounding areas, China

Abstract. Impacts of anthropogenic aerosols on clouds and snowfall during winter precipitation events remain highly uncertain, particularly under heavy pollution. A winter snowfall event over the Guanzhong Basin (GZB) and its surrounding regions (GZBs), China, has been simulated using a cloud-resolving, fully coupled WRF-Chem model to quantify the respective roles of aerosol–radiation interactions (ARIs) and aerosol–cloud interactions (ACIs). The simulated temporal variation and spatial distribution of air pollutants and precipitation generally agree with the observations in the GZB+GZBs. Sensitivity experiments are performed to evaluate effects of ARIs and ACIs by changing the anthropogenic emissions. The precipitation response to ARIs and ACIs exhibits regional contrast in GZB and GZBs due to different aerosol concentrations. In the GZB, exclusion of ARIs leads to a slight increase in precipitation with increasing emissions, mainly associated with enhanced ice-phase precipitation induced by ACIs. ARIs increase the precipitation in the GZB when emissions increase reaches a threshold, caused by ARI-induced enhancement of relative humidity (RH) which increases ice water path and favors survival of falling ice particles. In contrast, precipitation in the GZBs decreases with increasing emissions, reflecting suppression of liquid-phase precipitation by ACIs and reductions in RH caused by ARIs. In addition, changes in anthropogenic emissions exert limited influence on the spatial distribution of precipitation across the combined GZB–GZBs region. These findings provide process-level insight into how ARIs and ACIs regulate snowfall under polluted conditions, with implications for improving aerosol–precipitation coupling in regional climate and weather models.