Numerical Study of One Plateau Vortex Moving Eastward Affecting Heavy Rainfall in Sichuan

Based on auto-weather station network data, conventional observation data and T213 analysis data, using the MM5 mesoscale numerical model and T213 reanalysis data, simulation was conducted the Plateau vortex rainstorm occurring in Sichuan basin on 20 July, 2008.The simulated results show that:the Plateau vortex moving eastward promot the development of the positive vorticity over the Sichuan Basin, hence, the strong divergence at the tropospheric higher level and the convergence at the lower level are enhanced, and the convective precipitation may occur.The released latent heat of the precipitation may promote the development of the negative voritcity at the tropospheric higher level and the positive vorticity at the lower level.As a result, a positive feedback mechanism is forming, this feedback mechanism may support and maintain the vortex and the heavy rainfall over the Sichuan Basin.