Impact of transported dust aerosols on precipitation over the central
Himalayas using convection permitting WRF-Chem Simulation
Abstract
A substantial amount of dust aerosol was transported to the central
Himalayas during the multiple dust storm event that occurred from 12 to
15 June 2018 in the Thar desert, northwestern India. In this study, we
implemented a cloud-resolving Weather Research and Forecasting model
coupled with chemistry (WRF-Chem) to assess the impact of transported
Thar-related dust aerosols on precipitation processes over the central
Himalayas. We isolated the effect of the transported dust on the
precipitation distribution by zeroing out dust aerosols from lateral
boundary condition and keeping other species of aerosols. Results show
the noticeable impacts of transported dust aerosols on regional
precipitation and cloud properties over the central Himalayas. When
transported dust is included, spatially averaged (25°N-31°N and
78°E-89°E) AOD increases by 0.36. Over the Himalayas foothills with the
dust, precipitation is enhanced by 7.5% (0.63mm), while surface
temperature is reduced. The presence of mineral dust aerosols increased
the cloud droplets and ice crystal number concentration, which is
further facilitated by the mountainous terrain by orographic lifting,
leading to enhanced precipitation. We diagnosed the role of cloud
microphysics and that of the cloud dynamics in the simulated
precipitation sensitivity. This study highlights the effect of remote
dust aerosol on the perturbation of cloud microphysical properties,
which can significantly influence precipitation over the Himalayas and
impact the regional hydrology.