Rain Characteristics and Large-Scale Environment Associated with Extreme Precipitation Events Based on TRMM Observations

This study utilizes the Precipitation Feature (PF) database developed at the University of Utah to analyze extreme precipitation events from 13-year TRMM observations. Characteristics of instantaneous extreme volumetric PFs, their geophysical distributions and diurnal variations are examined and compared to those of intermediate and small systems. It is found that the instantaneous PF exhibits much larger scale range than daily gridded precipitation, with those at top 1% of PFs two orders of magnitude greater than the medium PF but contributing to over 50% of instantaneous rainfall. The study shows that extreme PFs are significantly larger, deeper and colder than the lower 80% of the PFs. NCEP reanalysis shows a systematic increase in surface moist static energy (MSE) with larger PFs but convective available potential energy (CAPE) levels off for extremely large systems. Mid-level relative humidity and total precipitable water increase consistently for increasingly heavy precipitation events, suggesting a potential role of increasing moisture in a warming climate in producing extreme precipitation events.