How different are tropical cyclone precipitation and convective properties during the evolution of fast-growing and slow-growing episodes

Analyzing a 16-yr Tropical Rainfall Measuring Mission (TRMM) satellite microwave imager (TMI) data for global tropical cyclones (TCs), this study examines the differences of various precipitation and convective properties in the TC’s inner core, specifically precipitation and convective intensity, symmetry, and frequency of various precipitation and convection types, during fast-growing (FG) versus slow-growing (SG) episodes. Instead of defining FG/SG as a 24-h period and treat each 24-h period as a separate case as in most previous statistical FG/SG studies, this work adopts an episode-based definition by consolidating all the continuous and overlapping 24-h FG/SG cases in each TC into FG/SG episodes to examine the evolution of each episode and compare the corresponding episode-relative stages between FG/SG episodes. The results show that FG episodes have significantly heavier rain rate, stronger convective intensities, more symmetric distribution of rain rate and convective intensity in the inner core for almost all corresponding episode-relative stages, compared with SG episodes. At the before-episode stage, FG episodes feature 11% heavier rain rate, 1% stronger convective intensity, 19% more stratiform rainfall frequency, 15% more shallow convection, 50% more deep convection, 21% more symmetric distribution of convective intensity, and 5% more asymmetric distribution of stratiform rainfall. These results can be used to improve FG predictions.