青藏高原四季降水变化特征分析

利用青藏高原87个地面气象台站41年（1960～2000年）的月降水资料，并在Arcgis 9.0中通过Kriging插值方法对少数站点的缺测值进行了插补，用线性回归方法研究了高原四季降水量的变化趋势及区域上的差异。为了保证本研究的完整性，对高原年降水也做了相应分析。结果表明：（1）高原冬春两季降水量呈显著增加趋势。冬季雅鲁藏布江下游、春季高原东北部为降水减少区，高原其他区域均表现为增加；夏秋两季降水量基本保持不变，但夏季高原中部和川西降水减少，高原南部和北部降水表现为增加；秋季高原中部、南部降水增加，川西降水减少。（2）高原年降水呈显著增加趋势。在区域上高原南部大致以东经102度为界，该线以东降水减少，以西降水增加，且降水增加区域表现出随纬度的增加而递减的特征。高原中部、北部的年降水基本保持不变或微弱增加。

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.