Different Aerosol Impacts on the Vertical Structure of Cold-Topped Convective Precipitation under Varying Meteorological Conditions in the Sichuan Basin

Aerosols influence convective precipitation through both radiative and microphysical effects, yet their impacts are strongly modulated by meteorological conditions. Using six years of precipitation profiles, this study examines how aerosols affect the vertical structure of cold-topped convective precipitation over the Sichuan Basin. Results show that under low Convective Available Potential Energy (CAPE) conditions, both precipitation top height (PTH) and precipitation rate exhibit a non-monotonic response to aerosol optical depth (AOD), first increasing and then decreasing. By contrast, under high CAPE conditions, PTH still increases and then decreases with AOD, whereas rainfall rate reaches a minimum at moderate AOD, indicating a decoupling between cloud depth and precipitation. This behavior is likely driven by stronger dynamical lifting that rapidly transports numerous small droplets aloft, where they freeze to form abundant small ice crystals. These crystals are inefficient at growing into precipitation-sized particles, thereby weakening rainfall despite deeper cloud development. It is also notable that, while evaporation is evident in the lower troposphere, precipitation at different layers and at the surface still responds consistently to AOD. Overall, the results highlight the strong dependence of aerosol-precipitation interactions on meteorological conditions and underscore the need for further investigation.