Investigation of the meteorological conditions, dynamical, and microphysical characteristics of convective precipitation over the rainfall center of South China in the Pre-summer Rainy Season

This study investigates the meteorological conditions, dynamics, and microphysical characteristics of convective precipitation in Longmen, South China, during the Pre-summer Rainy Season (PRS) from 2016 to 2020, focusing on the influence of the South China Sea summer monsoon (SCSSM) onset. Utilizing the ERA5 reanalysis dataset and observations from the C-band Vertical Pointing Radar (VPRC) and Two-Dimensional Video Disdrometer (2DVD), we analyzed 4560 Convective Precipitation Features (CPFs) and classified them into shallow convection (SC), middle convection (MC), and deep convection (DC) based on the maximum height of 35 dBZ echo-top. Key findings reveal that the onset of the SCSSM significantly enhances convective rainfall. Specifically, it increases the proportion of convective rainfall by 11 % and intensifies rainfall duration and intensity by approximately 2.2 times. Enhanced moisture convergence and stronger convective instability drive these changes. The microphysical processes are distinct across different CPF types. SCs display warm-rain processes, MCs indicate mixed-phase processes, and DCs are associated with ice-phase processes. Each type contributes uniquely to precipitation characteristics, vertical reflectivity profiles, and raindrop size distributions. These insights emphasize the SCSSM's critical role in regional precipitation patterns and provide valuable insights into the underlying processes affecting convective systems in South China, ultimately contributing to improving the capabilities of prediction in atmospheric research. [Display omitted] •After the onset of SCSSM, convective precipitation rate rises by nearly 2-fold, with an 11 % increase in the rainfall contribution•The VPR-C radar classifies convective precipitation, with SCs and DCs increasing by 5.9 % and 5.1 %, respectively; MCs decrease by 11.3 %•These convection types show different surface rain microphysics, with raindrop size distributions becoming more maritime-like•SCs are mainly associated with warm-rain processes, MCs with mixed-phase processes, and DCs with ice-phase processes