利用青藏高原83个站点的降水观测资料, 分析了1979 -2016年青藏高原降水的变化特征, 并基于ERA-Interim再分析资料的高空要素场, 从水汽输送角度进行初步解释, 得到以下结论: （1）1979 -2016年高原整体年总降水量呈不显著的增加趋势, 5月降水显著增加, 变化速率达到4.25 mm·(10a)-1, 12月降水显著减小, 9月降水先减小后增加。高原不同气候区降水的年循环变化差异较大, 根据分布型态和降水峰值的变化将11个气候区分为三类: 降水峰值显著增大的气候区3个, 包括藏南地区、 青南高原和羌塘高原等半干旱区; 分布型态显著变化的气候区4个, 包括东喜马拉雅湿润区、 横断山脉东南部湿润区和中北部半湿润、 阿里干旱区; 变化较小的气候区4个, 包括祁连山半干旱区、 柴达木干旱区和若尔盖湿润区和果洛半湿润区。（2）从降水变化趋势的空间分布来看, 5月大部分站点的降水呈增加趋势, 中部站点变化显著。12月大部分站点的降水呈减小趋势。（3）5月、 9月和12月水汽输送通量散度的变化与降水的变化趋势在空间分布上具有一致性。5月南亚夏季风的提前、 增强, 导致高原西南季风加强, 进而导致高原5月降水增加。12月东亚500 hPa高度存在气旋式环流异常, 导致高原上空北风分量增强, 向高原输送了更多干冷空气, 从而导致12月高原降水减少。
Precipitation change characteristics and its cause based on water vapor flux change in 1979 -2016 over the Qinghai-Tibetan Plateau (QTP) was analyzed, using precipitation observation from 83 stations and upper atmospheric fields from ERA-Interim.Main conclusions are drawn as following: (1) Annual precipitation averaged over the QTP shows increasing but non-significant trend in 1979 -2016.Precipitation significantly increases with the trend of 4.25 mm·(10a)-1 in May, but significantly decreases in December.Precipitation in September decreases at first and then increases.Annual variation shows different change characteristics in different climatic regions over the QTP.According to the changes in intra-annual distribution and peak value, 11 climatic regions can be classified into three types: 3 regions with large increase in peak value including southern Tibet, southern Qinghai and Chang Tang Plateau semi-arid region, 4 regions with large change in intra-annual distribution including east Himalaya and Southeast Hengduan Mountains humid region, north central Hengduan Mountains semi-humid region and Ali arid region, 4 regions with less change including Qilian Mountains semi-arid region, Chaidamu arid region, Ruoergai humid region and Guoluo semi-humid region.(2) In the case of precipitation trend distribution, most of the stations show increasing trend over the QTP in May, particularly for the middle region with significant change.Trends in December show overall decrease.(3) The distributions of water vapor flux divergence change are in good agreement with the distributions of precipitation trends in May, September and December.Advance and enhancement of South Asia monsoon brings more humid southwesterly, making more precipitation over the QTP in May.While in December, an anomalous anticyclone exists in the East Asia at 500 hPa, resulting in intensified northerly and associated dry cold air over the QTP, which leads to less precipitation.
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