Contrasts in Microphysical Characteristics Between the Meiyu Warm-Sector and Frontal Heavy Rainfall in East China

Microphysical characteristics of heavy rainfall during the Meiyu season are revealed using observations from a novel network of 293 disdrometers collected over four Meiyu seasons and Global Precipitation Measurement Dual-Frequency Precipitation Radar data spanning nine seasons. Heavy rainfall events are classified into the warm-sector (Warm) and frontal (Front) types based on their locations relative to the Meiyu fronts. Compared to the Front type, the Warm type shows a significantly deeper convective structure with a larger number of large-size hydrometeors. This results in lower number concentration and larger mean size of surface raindrops. Further analysis combining diurnal cycles and environmental thermodynamic and dynamic conditions reveals that convection associated with the Warm type tends to develop in the afternoon due to solar heating, whereas that of the Front type primarily occurs at night, driven by strong low-level moisture convergence and dynamical lifting near the frontal zone.