Statistics And Numerical Simulation Of The Typhoon Rainstorm Influencing Guangxi Beibu Gulf

We made large numbers of statistical calculation and study about typhoon rainstorm in Guangxi Baibu Gulf from 1970 to 2004. The results shows: the decade difference of typhoon rainstorm was little remarkable. In the 35 years, there are 81 rainstorms resulting from typhoon, about 2.3 rainstorm each year ,most of them occurred in the July and August and September. In the meantime, with the ECMWF data of tropical wind field, atmospheric pressure field and height field, especially wind vector field in tropical area, this paper provides some important evidences for the generation and development of the typhoon and the analysis of the atmospheric current field of its torrential rain. The factor for Baibu Gulf typhoon torrential rain not only depend on the landing place, the tracking, the center of typhoon if entering the inland of Guangxi, but also are closely relatedto the position Subtropical High, the changes of it intensity. In typhoon's landing process, the factors that the southern jet stream in its east side, southwestern jet stream, the influence of cold air and the atmospheric vortex enters Guangxi near Baibu Gule play an important role for the typhoon torrential rain in Baibu Gule.In order to make clear the interaction between typhoon and mid- latitude system, we made numerical simulation test and physical diagnosis of 0107 typhoon in 2001. It is found that the connection between the Subtropical high and typhoon periphery enhanced the low-level jet and transportation of water vapor, low level jet are closely related with the middle level divergence, the maintain of Meso-scale Vortex in middle - high level and the characteristic of its incline vertically and the coupling between high and low jet stream provide impetus condition for typhoon rain-storm through upper level convergence at the low layer and marked divergence at upper layer.After further studies using diagnostic analysis method, we found that: there is a clear thick structure of Vortex and Divergence center, and there are strong rising air currents in the rainstorm area. And energy and stability and vapor conditions are also in favor of the occurrence of the rainstorm.