Regional Variability of Precipitation in Tropical Cyclones Over the Western North Pacific Revealed by the GPM Dual-Frequency Precipitation Radar and Microwave Imager

A knowledge of precipitation microphysics of tropical cyclones (TCs) is crucial for forecasts of the TC track and intensity using numerical weather models. Based on five years of measurements of TCs over the western North Pacific from the dual-frequency precipitation radar and the microwave imager on board the Global Precipitation Measurement satellite, the precipitation characteristics and microphysical processes in different regions of TCs and their associations with ice scattering signals are investigated. In the region close to the TC center, the storm top height (STH) and near-surface rain rate are high, and the hydrometeors have a high concentration and a relatively low mass-weighted mean diameter (Dm). In the outer TC region, the distributions of the reflectivity factor (Ze) and Dm become broader as the mean Dm increases. Ze and Dm values generally increase below the melting layer, indicating the predominant role of collision-coalescence processes. The occurrence probability of collision-coalescence is greater than 90% when STH is less than 5 km and the polarization-corrected temperature at 89 GHz is greater than 250 K. When the STH exceeds 5 km, the collision-coalescence process is also predominant in the eyewall region; however, the influence of the breakup process increases in the rainband regions.