The Analysis Of The Vortex And Mesoscale Convective System During A Heavy Rainfall Event In Southeast Sichuan Province

Using JICA(Japan International Co-operation Agency) surface observed data,micaps surface observed rainfall data,radar data,1°×1°(longitude±latitude) NCEP reanalysis data and WRF model simulation high resolution output data, the vortex and mesoscale convective system(MCS) during a heavy rain event in Southeast Sichuan Province from 30 June to 1 July 2008 is investigated.The diagnostic analyses indicate that the vapor of low level mainly came from the Bay of Bengal and the South China Sea.The JICA 3-h temperature variation shows that the cold air from the northern accumulated in southeast Sichuan Basin,which provided advantage of the formation of surface convergence line. The numerical simulations reproduce well the coupling interaction among the vertical ascent movement of the south entrance region of upper level jet and the front of short wave trough moved form Plateau and the northern of surface convergence line leads to the formation and development of Mesoscale Convective System,and brings the heavy rain. The model simulation also indicates that the 850hPa vortex forms precede 700hPa's vortex,the mountain and southwest low level jet stream have positive role to the development of 850hPa vortex. Through the diagnostic analyses of PV,latent heat rate and non-adiabatic heating Omega equation show that the latent heat heating has the important influence on the formation of the 700hPa vortex.The"dry"experiment shows latent heat release can lead the 700hPa cyclone shear to develop into votex,but it has little influence on the formation of 850hPa vortex.