Statistical Analysis on the Plateau Low Vortex Activity Characteristics

The activity characteristics of the Plateau Low Vortex are investigated by using the yearbook Qinghai-Xizang Plateau vortex from 1998 to 2011. The results showed that:of 14 years, the plateau vortex appeared five hundred and sixty-one times, including four hundred and sixty-six times in eastern plateau vortex, ninety-five timesin western plateau vortex;the plateau vortex occurrences increased year by year from 2000 to 2009;the plateau vortex occurred mainly in the summer and the monthly changes significantly, up to July, the number of occurrences which, in February there is at least;there are two system including low slot and shear which influence the plateau vortex moving out of the plateau, respectively, 28.8%, 71.2%.