TRMM卫星降水数据在雅鲁藏布江流域的适用性分析

以雅鲁藏布江流域为研究区,利用16个气象站点的实测降水量在月尺度和日尺度上验证了TRMM(Tropical Rainfall Measurement Mission)卫星降水数据的精度,并在此基础上基于TRMM月降水数据分析了雅鲁藏布江流域的降水时空分布特征。结果表明:在整体上,TRMM月降水数据与站点实测降水量相关系数R=0.902,斜率K=0.849,数据精度较高,数值上比站点实测降水量略微偏低;就单个站点而言,大部分站点相关系数较高,偏差较小,但波密站相关系数相对较低,江孜站和南木林站数据偏差相对较大。TRMM日降水数据与站点实测降水量相关系数R=0.466,斜率K=0.451,数据精度较低,与站点实测降水量一致性较差。在降水空间分布上,雅鲁藏布江流域整体呈现由西向东逐渐递增的趋势,不同区域间差异极其明显;在降水时间分布上,大部分降水集中在6至9月,12月至第二年2月很少有降水发生。

The Applicability Analysis of TRMM Precipitation Data in the Yarlung Zangbo River Basin

The Yarlung Zangbo River is a trans-boundary river of crucial importance to China with great potentiality in hydropower resources. However, the precipitation gauge stations are dramatically sparse in this basin due to high elevation, complex topography and severe climate, especially in the western part of the basin. Precipitation estimation from satellites provides potential alternatives in precipitation measurements in regions where conventional precipitation gauges are not readily available. In this study, the performance of TRMM (Tropical Rainfall Measurement Mission) monthly and daily precipitation data over 1998－2010 were evaluated in the Yarlung Zangbo River Basin with rain gauges from 16 meteorological stations. The evaluation revealed strong correlation and little numerical biases between TRMM monthly precipitation data and rain gauges in general, while the correlation coefficient in Bomi station was comparatively lower and the biases in Jiangzi station and Nanmulin station were comparatively higher. While on the daily basis, the correlation between TRMM precipitation and rain gauges is relatively weak. On the basis of the evaluation, the spatial and temporal patterns of the average annual and monthly precipitation over the basin were analyzed with TRMM monthly precipitation data. There is an increasing trend from west to east and strong spatial variability in the average annual precipitation. Precipitation peaks in July and most of the total annual precipitation occur during June to September. Precipitation hardly occurs during December to February next year.