Linking Ice‐Phase Microphysics to Raindrop Characteristics in Deep Convection: A Warm‐Sector Extreme Rainfall Case Study in Eastern China

Abstract

In this study, we examine the evolution of ice‐phase microphysics [polarimetric radar signatures and identified graupel and hail (GH) (hereafter, GH) distributions] and raindrop characteristics [drop size distribution (DSD) and rainfall intensity] in a warm‐sector extreme rainfall case during the Meiyu period in Eastern China. Deep convection is identified in this rainstorm, raindrop characteristics are found to be deeply affected by the GH distribution condition, heavy rainfall (rain rate >20 normalmnormalm0.25emh−1 $\mathrm{m}\mathrm{m}\,{\mathrm{h}}^{-1}$) is basically contributed by convective samples with GH identified aloft. As GH height rises, number concentration and mean size of raindrops increase accordingly, leading to the growth of rainfall intensity. Extreme rainfall (rain rate >100 normalmnormalm0.25emh−1 $\mathrm{m}\mathrm{m}\,{\mathrm{h}}^{-1}$) is majorly induced by deep convection with hail or widespread (over 10 km level) graupel, melting of the abundant highly‐rimed particles plays a dominant role in generating high concentration raindrops. By revealing the link between GH distribution conditions and raindrop characteristics, the study helps to understand the specific role of ice‐phase processes to the formation of low‐level raindrops in deep convection.