Observational structure and physical features of tropical precipitation systems

Abstract

To understand the formation and evolution of tropical rainfall, this study examines macro- and micro-physical features and vertical structures of tropical precipitation systems (TPSs) using 9-years observations from the Global Precipitation Measurement (GPM) mission's dual-frequency precipitation radar (DPR). TPSs are primarily convective-dominated, and their precipitation rate (PR) concentrated in 20–40 mm/h, which can be largely attributed to liquid hydrometeors, especially in convective regions. However, TPSs with low PR (below 10 mm/h) are stratiform-dominated. The mean levels of 0 °C and − 40 °C within the TPSs are 4.9 km and 11 km, respectively. Warm core is observed in the TPS, which is related to the development of precipitation system. TPSs have distinct characteristics during different stages of their lifecycle. Condensation and autoconversion processes in convective cores contribute to the formation of initial small droplet below 3 km. With the development of TPSs, strong updrafts in convective cores transport droplets from cloud base to higher levels, facilitating the collision-coalescence process in liquid phase layers. During the developing and mature stages, aggregation and riming processes become active above the melting layers. The large hydrometeors within the convective cores contribute to high PR of mature-stage TPSs. In stratiform region, droplets sizes are larger during mature stage than dissipating stage, and these larger droplets may detach from the convective cores. It makes the dominate microphysical process in stratiform regions of mature (dissipating) stage is breakup (evaporation) of raindrops. These results advance the understanding of tropical rainfall and establish a foundation for future research into validating and improving cloud microphysical parameterization schemes in numerical models.