Analysis of Temporal and Spatial Characteristics about Upper-air Temperature over Tibetan Plateau during Last 30 Years

The annual and seasonal characteristics about upper-air temperature in Tibetan Plateau are analyzed on the basis of monthly mean radiosonde records of 16 meteorological stations from 1979 to 2008.The results show that the spatial characteristic of annual mean upper-air temperature is high consistent with that of season over Tibetan Plateau, and in summer it is the weakest.Annual and seasonal characteristics of mean upper-air temperature show that January is the coldest and July is the warmest from 500 to 250hPa and from 30 to 20hPa, while it is contrary from 100 to 70hPa.Annual mean temperature from 500 to 250hPa is rising, while that up 150hPa is falling.The falling, dated from 1984, is significant.