基于高分辨率格点观测数据的青藏高原降水时空变化特征

基于青藏高原地区1961-2010 年高分辨率的逐日降水格点资料,按多雨区、相对少雨区、相对多雨区、少雨区和干旱少雨区选取青藏高原8 个研究区域。对近50 a 青藏高原年和季节降水量的分布形式以及变化趋势进行了分析。结果表明:青藏高原平均年降水分布不均匀,存在区域差异,呈现出由其东南部向西北部递减的分布形式。且同时存在季节差异,夏季降水最多,其次是春季和秋季,冬季降水最少。其中夏季降水分布形式与年降水分布形式对应较好;其他季节降水普遍集中在高原南部、东南部以及西南部。年降水变化以102°E为界,以东降水逐年减少,以西增加。季节降水变化趋势存在明显的区域和时域差异,在降水量较大的季节和区域,其降水增加趋势相应较大,反之较小。四季中除了夏季位于高原中东部较大范围的降水减少区以及冬季拉萨地区附近的两个降水减少中心外,其他地区各季节都表现出降水增加的趋势。

Spatial and Temporal Characteristics of the Precipitation over the Tibetan Plateau from 1961 to 2010 Based on High Resolution Grid-observation Dataset

Based on high resolution data of the daily precipitation over the Tibetan Plateau (hereafter TP) from 1961 to 2010, the spatial and temporal characteristics of precipitation over the TP are studied. According to relatively heavy rain, rainy, relatively little rain, little rain and drought area, the whole TP is divided into eight subareas, which represent the amounts of precipitation in the region. The trend and distribution of annual and seasonal precipitation over the TP are analyzed and discussed during the studied period. The results show that the distribution of the average annual precipitation over the TP is uneven and has spatial differences, decreasing from the southeastern to northwestern TP. At the same time, the precipitation has seasonal differences, with largest/smallest amount in summer/winter, followed by spring and autumn. The distribution of precipitation in summer is like the annual average precipitation. In other seasons, the precipitation is generally concentrated in the southern, southeast and southwest TP. The trends to the east and west of 102°E are quite different in the TP. The trend of seasonal average precipitation is obvious, dominated by region and time. Regions with larger average precipitation also have larger magnitudes of increase. Each subarea has increased precipitation in each season, except the large area in the eastern TP having decreasing trend in summer, and regions around Lhasa having reduced trends in winter.