NUMERICAL ANALYSIS OF THE PBL STRUCTURE FOR A RAINSTORM CASE

In the paper, the planetary boundary layer (PBL) structure for the 28 July 1979 Tangshan rainstorm on the north edge of the subtropical high is diagnosed by use of the of the 9-level unequal-interval PBL model. The synoptic scale variables are interpolated to the upper boundary of the model and the observed wind data at the 1500,900,600,300m levels and the surface are utilized. The effects of thermal stratification and baroclinicity on wind distribution in the PBL are taken into account. The dynamic adjustment scheme is applied to get the wind fields at the model levels, The computed wind fields show that there are a clear convergence zo ne and cyclonic circulation in the lower layer of the PBL. The vertical fluxes of momentum, heat and moisture at the surface as well as the fields of vertical motion, vorticity and divergence at all levels are calculated by using the model. It is clear that the results give full details of the thin structure of the PBL and show the effects of topography forcing. And the quality and ability of the used PBL model are furthes checked.