Aerosol–precipitation elevation dependence over the central Himalayas using cloud-resolving WRF-Chem numerical modeling

Abstract

Atmospheric aerosols can modulate the orographic precipitation impacting the evolution of clouds through radiation and microphysical pathways. This study implements the cloud-resolving Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to study the response of the central Himalayan elevation-dependent precipitation to the atmospheric aerosols. The first monsoonal month of 2013 is simulated to assess the effect of aerosols through radiation and cloud interactions. The results show that the response of diurnal variation and precipitation intensities (light, moderate, and heavy) to aerosol radiation and cloud interaction depended on the different elevational ranges of the central Himalayan region. Below 2000 m a.s.l., the total effect of aerosols resulted in suppressed mean light precipitation by 19 % while enhancing the moderate and heavy precipitation by 3 % and 12 %, respectively. In contrast, above 2000 m a.s.l., a significant reduction of all three categories of precipitation intensity occurred with the 11 % reduction in mean precipitation. These contrasting altitudinal precipitation responses to the increased anthropogenic aerosols can significantly impact the hydroclimate of the central Himalayas, increasing the risk for extreme events and influencing the regional supply of water resources.