The Middle-Upper Circulation Analyses of the Plateau Vortex Moving Out of Plateau and Influencing Flood in East China in Recent Years

Using the NCEP reanalysis data,the middle-upper troposphere moving east activity characteristics of the Plateau vortex that induced severe rain storm and flood in different regions of China are analyzed in 1998—2004.Results show that there are four synoptic types for the Plateau vortex moving out of the Plateau,they are Plateau vortex of north trough and south vortex type,Plateau vortex on shear line,Plateau vortex in shear stream field and Plateau front of the west wind trough.And the relationships between the moving out of the Plateau vortex and the cold air at 500 hPa,the position of the Subtropical High,the south Asian High and the westerly jet stream are revealed.The common character of them had been pointed out and the strong signals of the moving out of the Plateau had been pick up.All these had presented scientific witness to the prediction storm rainfall induced by the Plateau vortex.