Comparative analysis between two summer heavy rain events in Yibin based on the TRMM data.

Using the observational data from the TRMM satellite and Doppler radar at Yibin， the Vertical Wind Profile (VWP) change characteristics, rainfall structure characteristics and rainfall profiles for the two regional heavy rain events in Yibin in 2007 are analyzed in this paper. The results show that: (1) The two precipitations are all caused by mesoscale systems as indicated by their respective horizontal rainfall pattern, and although the rainfall intensity and scope of the event occurred in July are much larger than those of the event in August, their vertical structure implies a severe convective cloud cluster developed therein with its cloud top height up to 17, 14 km; (2) the difference between the two profiles of stratus precipitation rate is not distinct with the trend of precipitation intensity was reduced with increasing height, while their convective precipitation rate profiles are quite different from each other with the shifting direction of precipitation growth areas being just opposite: for the former event the area is shifted from coagulation layer to mixed layer and for the latter it is from mixed layer to coagulation layer; (3) the typical vertical circulation structure of convergence in lower levels and divergence in upper levels is found over the heavy/torrential rain areas in the “Julyevent” based on the VWP data with the precipitation cloud clusters moving continuously, but there exists no such a typical structure with the “Angust event” in which the alternative warm or cold advection occurs in the case of easterly waves coming and the activity of rainfall is discontinuous.