2026/07/27 by Weixi Shu, Danhong Fu, Xueliang Guo +1
paper · doi:10.1175/mwr-d-25-0252.1
Abstract Interactions of cloud microphysical processes with a mesovortex pair (MVP) in a short-term extreme rainfall event with a record-breaking hourly rainfall of 201.9 mm in Zhengzhou, China on 20 July 2021 are investigated using numerical simulations. The results indicate that the simulations can well capture the observed hourly extreme rainfall accumulation and the high liquid water content in association with warm cloud microphysics. It is found that the tilting updrafts within and horizontal flow around the MVP play crucial roles in transporting surrounding rainwater into the same location and producing the extreme hourly rainfall, indicating that the formation of the short-term extreme rainfall event is closely related to the interactions between the MVP and cloud microphysics. Rainwater transported from the northeast, south, and northwest directions accounts for 35.4%, 23.6%, and 30.2%, respectively in the extreme rainfall region. The relative contributions of rainwater to total rainwater from warm and cold microphysics are about 70-80% and 20-30%, respectively. The maximum conversion rate for the collection of cloud water by rainwater in warm microphysics reaches 3.5×10 −2 g kg −1 s −1 , while that from the melting of graupel to rainwater in cold microphysics is 1.5×10 −2 g kg −1 s −1 . This study expands our understanding of interactions between mesovortices and cloud microphysics in the formation of extreme rainfall events through rainwater transport processes driven by tilting updrafts and horizontal flow in association with mesovortices.