Aerosol impact on precipitation and cold pools over an arid region

Abstract

This study investigates aerosol impacts in the primary and secondary convective cells and their associated cold pools resulting from the convective outflow over the dry and arid regions of the Indian peninsula. A convective event observed with C-band polarimetric radar is analysed through several numerical simulations, focusing on the impact of aerosol on rainfall and cold pool characteristics. Control simulations were conducted with low, moderate and high cloud condensation nuclei (CCN). Additional sensitivity experiments introduced more ice nuclei particles (INP) in both the primary and secondary convection areas with supercooled liquid water content. The introduction of more INP in all experiments resulted in more ice crystals, snow, hail, as well as an enhancement of high-intensity rainfall. In the primary convection area, the addition of INP led to enhanced mass flux, snow, hail, and melting of hail, which contributed to enhanced area averaged rainfall (>1 mm) and an increase in the cold pool area. However, no significant change was observed in the speed and depth of the primary cold pool depending on the low/high INP simulation. Addition of INP in the secondary convection area did not notably affect the strength or area of the cold pool. Overall, the study highlights that the spatial features of convection and cold pools are modified by the introduction of additional ice forming aerosols.