CHARACTER ANALYSIS IN VARIATION OF SEASONAL PRECIPITATION OVER THE TIBETAN PLATEAU

In this paper,the trend in change of seasonal precipitation and its regional difference in the Tibet Plateau were analyzed for the last 41 years on basis of the long-term precipitation data at 87 meteorological stations in the Plateau.Missing data were interpolated by using Kriging interpolation with the ArcGIS 9.0.To make the research be complete,annual precipitation in the plateau was also analyzed.The results showed that there is an obvious increase in precipitation during spring and winter,and no such increase in summer and autumn.Decreasing trend of precipitation occurs in the lower reaches of the Yarlung Zangbo River in winter,northeast Tibetan Plateau in spring,central Tibetan Plateau in summer,and west Sichuan Province in summer and autumn.And increasing trend of precipitation appears in the remaining Plateau of decreasing region in winter and spring,south and north Tibetan Plateau in summer,and central and south Tibetan in autumn.It was found that there is an obvious increasing trend for the annual precipitation in the Plateau.There is a boundary at about 102°E in south Tibetan Plateau,with decreasing trend in east of the boundary and increasing trend in the west of it.As the latitude increases,the increasing trend weakens.The annual precipitation showed no obvious trend in central and north Tibetan Plateau.