Analyses on Mean Circulation Field of the Plateau Low Vortex Moving Out of Tibetan Plateau

Using the NCEP reanalysis data,the activity characteristics of the Plateau low vortex moving out of the Tibetan Plateau in each month in summer from 1998 to 2004 are analyzed.Furthermore,the compared analysis of the monthly mean geopotential height,geopotential heightdifference distribution,temperature,wind field between the more vortex moving out of the Plateau in June,July and August and less vortex moving out of the Plateau rule is gotten.The different characteristics between the Plateau vortex over the Plateau and the vortex moving out of the Plateau and the mean circulation field characteristics of the Plateau vortex moving out of the Plateau were acquired.All this had offered a scientific background for the prediction of the Plateau vortex which lead to the storm rainfall.