NUMERICAL STUDY OF A MESO-β SCALE RAINSTORM EVENT^*

Diagnosis is performed of a thunderstorm rainstorm event occurring in the summer of 1996 at Nanjing and numerical simulation undertaken in the context of hydrostatic equilibrium framework of MM5 as the fifth version of the PSU/NCAR mesoscale model. Analyses show that the rainstorm-associated thermal condition was the accumulation of unstable potential energy and the dynamic condition was vigorous convergence updrafts. And the simulation within the hydrostatic framework indicates the significant role of latent heat release in the rainstorm occurrence: that even for a 30 km grid spacing horizontally of great importance to the successful modeling of the meso-p event was a convection parameterization scheme that led to less rainfall in our run based only on its explicit version but to the prediction in closer agreement with the observed when its implicit version was used in combination: for the thunderstorm-accompanied torrential rain. the Grell scheme was superior to the version of Kuo and the improved Arakawa-Schubert parameterization scheme (Grell 1993:Anthese and Kuo 1987; Arakawa and Scherbt 1974: Grell et al. 1991).Moreover, better results came from the simulation in the context of hydrostatic framework of the MM5 compared to those from the run within the nonhydrostatic equilibrium framework, a problem that awaits further efforts.