Comparing the Strength of Eyewall, Inner Rainband, and Outer Rainband Convection Using 10 years of TRMM Data

The Tropical Rain Measuring Mission (TRMM) satellite has passed over more than 900 tropical cyclones since its launch in 1997. Previous studies have established that the intensity of convection in the eyewall (<50~100-km radius from the storm center) is greater than that in the rainbands, and stronger convection often accompanies more intense storms (i.e., defining intensity of the tropical cyclone by its maximum wind speed). However, the question remains on how the strength of convection in the eyewall or rainbands varies as a function of storm intensity and intensity change. This study is aimed at answering this question with 10 years of TRMM observations. Over 0.1 million Tropical Cyclone related Precipitation Features (TCPFs) have been identified from the 10 year University of Utah TRMM Precipitation Feature (PF) database. The TCPF database includes TRMM tropical cyclone observations from six basins: Atlantic (ATL), east+central Pacific (EPA), northwest Pacific (NWP), north Indian Ocean (NIO), south Indian Ocean (SIO), and south Pacific (SPA). In this study, we categorize eyewall, inner rainband and outer rainband PFs subjectively based on the horizontal fields of radar reflectivity and 85-GHz ice scattering. Properties of these PFs related to convective intensity including radar reflectivity profile, maximum height of 20 dBZ echo, minimum brightness temperature in IR and passive microwave channels (37 and 85 GHz), flash rate, and others are examined. First, we establish the composite distributions of these properties for eyewalls and rainbands as a function of storm intensity and intensity change. Then, we examine these distributions for different basins and over-land vs over-ocean. Finally, we show examples of extremely intense convective events, compare them to the composite distributions, and explore their potential significance to the evolution of the storms in which they appear.