Comparative analysis of precipitation structures in two Southwest China Vortex events over eastern Sichuan Basin by TRMM

Abstract

The analysis of two rainfall structures of Southwest China Vortex (SCV) during June 14–15, 2008 (event 1) and July 8–9, 2010 (event 2) over eastern Sichuan Basin is presented by using observations from Tropical Rainfall Measuring (TRMM). Through comparisons with statistics of convective and stratiform precipitation, corrected polarization temperature, precipitation particles and latent heat for these two SCV events, similarities and differences of the cloud and precipitation features in eastern Sichuan Basin are discussed. It is found that the stratiform precipitation contributes the largest percentage of rainfall with SCV prolong. The horizontal scales of the two SCV clouds are generally equivalent but the percentage of convection precipitation in the event 2 is larger than those in the event 1. The melting layer (below the 0 °C height) precipitation contributes more than 60% of total precipitation, which suggests that both of the two precipitation events tends to have more properties of warm rain process. The 85.5 GHz corrected polarization brightness temperature of TRMM Microwave Imager (TMI) is possible to infer the strength of convection development. The ice particles are the main rainfall source with high contents around the 0 °C height of the cloud, and the vertical distributions of ice particles are similar in the two events. The liquid particles in the event 2 concentrate 2–4 km higher in vertical compared with the event 1. The latent heat release has a vertically bimodal pattern in the event 2 while a vertically unimodal pattern in the event 1. In the two events the latent heat release in the eastern part of SCV is at least 1.5 times more than that in the western part and the peak value of eastern SCV latent heat in the event 2 is twice as much as that in the event 1.