Utilizing datasets from the precipitation phenomenon instrument in Zhengzhou,dual-polarization radars,conventional observations,and China’s First Generation Global Atmosphere and Land Reanalysis data,this study analyzes the microphysical characteristics of the “7·20” extremely heavy rainfall event in Zhengzhou.The occurrence of this extremely heavy rainfall was influenced by multiscale weather systems,creating conducive environmental conditions for the development of complex microphysical characteristics.The results reveal significant changes in raindrop size distributions over time,with raindrop size distribution parameters exhibiting a wide range of values.These parameters encompass distributions typically seen in continental convective precipitation as well as maritime convective precipitation.Notably,the density of small drops exceeded that of common convective precipitation observed in East Asia and South China during the summer.Simultaneously,a large number of large drops existed,contributing to heightened precipitation efficiency,particularly during the most intense precipitation period,which occurred from 16:00 BST to 17:00 BST on July 20th.The dual-polarization radar observations illustrated a low-centroid structure within the convective storm,indicative of warm cloud characteristics.Furthermore,the study highlights the significant role played by intense warm-rain processes beneath the 0 ℃ layer in the formation of this extremely heavy rainfall event.This role involved the melting of numerous ice particles and the facilitation of efficient growth in raindrop size.