Convective and Rainfall Properties of Tropical Cyclone Inner Cores and Rainbands from 11 Years of TRMM Data

Abstract

onvective and rainfall properties of tropical cyclones (TCs) are statistically quantified by using Tropical Rainfall Measuring Mission (TRMM) data from December 1997 to December 2008. A semimanual method is used to divide the TC raining area into inner core (IC), inner rainband (IB), and outer rainband (OB) regions. Precipitation features (PFs) within these regions are compared for their convective vigor and rainfall characteristics based on passive microwave, infrared, radar, and lightning properties. Strong convective signatures are generally found more often in precipitation features in the IC region, less often in the IB region, and least often in the OB region when examining features with sizes greater than 1000 km2. However, at the very strong end of the convective spectrum, the magnitude of ice scattering signatures in OB features tends to be comparable and even stronger than that in IC features. The flash density when normalized by the raining area is about 2?3 times higher in IC features than that in OB features for all TCs except for category-1?2 hurricanes, in which the flash density is comparable for IC and OB features. The flash count per raining area in IB features is a factor of 2 (4) lower than that in OB (IC) features for all TC intensity categories on average. This confirms the bimodal radial distribution of flash density as suggested by previous studies. However, instead of a weaker maximum in the IC region and a stronger maximum in the OB region, this study finds a stronger maximum in the IC region and a weaker maximum in the OB region.