A Study On Wudou Vortex And Its Representative Synoptic Process

Wudou vortex is part of the tibetan plateau vortex, and the side of the whirlpool of the research is concentrated in the 1980s and the early 1990s. Because of various restrictions, it was making slow progress and limited depth on Wudou vortex study. Therefore, there is great significance of science and reality for further research of Wudou vortex.Based on NCEP reanalyzed data during the year 1998-2008(May-October), the activity of Wudou vortex is researched. The research reveals the climatic features such as frequency of vortex activity, producing origin, moving path, its lifetime, and evidence for precipitation in south east of the northwest China. And four influencing synoptic system model were offered to provide evidence for forecasting on Wudou vortex in south east of the northwest China:North trough-Subtropical high over the west pacific, North trough-The tibetan plateau vortex, The northeast vortex-Subtropical high over the west pacific, and The tibetan plateau vortex-Subtropical high over the west pacific.The two similar storm rainfalls on June 30 and July 21,2008 in Longnan disaster area are analyzed by the diagnostic and contrast method. And the former was main influenced by Wudou vortex but the the latter was main influenced by tibetan plateau vortex.The analytic conclusions are as follows:Because less of the condition of vertical ascending motion, and less full use of water vapox, storm rainfall influenced by Wudou vortex was less strength and region, but because of more vertical ascending motion, storm rainfall influenced by tibetan plateau vortex was more strength and region.Based on the numerical model (WRF3.0), the simulated experiment for developed Wudou vortex is carried out on 24 hours of 29-30 June 2008. The results show that simulated flow, simulated height fields and simulated vorticity on 500hPa level are agreement with observations. Wudou vortex is shallow mesoscale convection system on 700-600hPa level. When wudou vortex developed powerful, there were stong divergence and intensive vorticity in the center of Wudou vortex, and several small vertical circulations in the main vertical circulation. The simulated fainfall area and the precipitation intensity are agreement with the observations.