Numerical simulation of a pulse hailstorm in the plateau region in southwestern China

Abstract

Pulse hailstorms over southwestern China generally produce small hailstones with diameters <20 mm, causing nonnegligible damage to crops. This study examines the mechanisms behind the typical pulse hailstorms which frequently occur in plateau regions in southwestern China. Utilizing radar observations and the Cloud Model 1 (CM1) numerical model developed by George Bryan, the influence of environmental factors on pulse hailstorms and the associated small hailstones is investigated. The results indicate that: firstly, hailstones are primarily generated from frozen droplets, which further grow through collecting supercooled liquid water; secondly, a higher convective available potential energy (CAPE) and lower low-level relative humidity (RH) lead to the raising of convection initiation height; and lastly, higher CAPE values result in smaller hailstones on the surface due to the intensified hailstone melting process caused by higher melting layer and warmer temperatures within the warm layer (>0 °C) in this situation.