Microphysical Processes of a Heavily Precipitating Event in TiMREX

After the onset of the East Asian Monsoon during mid to late May, heavy precipitation frequently occurs in southern China and Taiwan. Despite decades of research, prediction of heavy rainfall in this region is still limited by imperfect understanding of the storm structure, evolution, and microphysics of precipitation features embedded in the Mei-Yu fronts and complicated by the presence of the mountain ranges. Previous studies have documented the factors and mechanisms leading to heavy rainfall such as strong southwesterly jet, frontal continuously triggered convection, and orographic effects, but microphysical processes responsible for the heavy rainfall are unknown. In one of the heavy precipitation events during Mei-yu season in 2008, new convection keeps developing and feeding the large precipitation shield. It is unknown whether significant ice mass is present in most of the convective cells that feed the long-lived cloud and precipitation system. Our working hypothesis is that large amount of ice mass are transported into the mother MCS from those newly developed convective cells and produce heavy rainfall through subsequent aggregation and melting of precipitation-size ice particles. This paper asks to what extent these ice-based processes contribute to the excessive rainfall. Information about hydrometeor type, concentration, and location can be derived from NCAR's S-band polarimetric radar deployed in TiMREX. This provides a possible way to evaluate the relative importance of ice-based versus warm-rain processes in the convection contributing to this long-lived heavily precipitating event.