A microphysical investigation of different convective cells during the precipitation event with sustained high-resolution observations

The growth and breakup processes of raindrops within a cloud influence the rain intensity and the sizes of raindrops on the surface. The Doppler velocity spectrum acquired by a vertically pointing radar (VPR) contains information on atmospheric turbulence and the size classification of falling hydrometeors. In this study, the four types of Convective Cells (CC) during precipitation events with more than 700 mm of precipitation in southern China are described. The characteristics of four types of CCs correspond to the isolated convection, the early stage, the mature stage, and the decline stage of organizational convection, in that order. Microphysical analysis using retrieval of vertical air motion (Vair) and raindrop evolution in clouds from Doppler velocity spectra collected by C-band VPR revealed the growth and breakup of falling raindrops with dynamic impact. Larger raindrops appear in the early stages and are accompanied by ice particles, which are impacted by the falling path’s downdraft. Raindrop aggregation, which is primarily related to the alternation of updraft and downdraft, accounts for the mature stage’s high efficiency of surface rainfall. The CCs in the decline stage originate from the shallow uplift in the weak and broad downdraft under conditions of enough water vapor. The updraft dominates the stage of isolated convection. Observations of convective cells could be more accurately represented in model evaluations.