TMPA卫星降水数据的评估与校正

Assessment and correction of TMPA products 3B42RT and 3B42V6

卫星遥感降水由于时空分辨率的优势在现代水文模拟中正起着越来越大的作用。本研究对黄河源区的两套卫星降水产品(TMPA准实时3B42RT和研究数据3B42V6)进行了详细评估,结果表明,3B42RT与3B42V6相比会明显高估地面降水,而两者对降水事件的反演能力基本一致。通过引入"降水重心"的概念,两套卫星降水产品均可以基本反映降水的空间分布及长期演变过程。在两者尤其是3B42RT数据的校正中,首先将卫星数据与地面站点月降水对比,再等比例降尺度回日降水,然后尝试逐步订正和最优插值两种残差处理方法,从而使降水量和降水分布的精度进一步提高。最后用校正后的卫星降水驱动分布式水文模型,利用输出径流间接验证校正的效果。

The application of Satellite Remote Sensing precipitation has great potential in modern hydrology.In this paper,two sets of TMPA products：3B42RT and 3B42V6 are evaluated and corrected in the areaof the headwater region of the Yellow River. Although RT product highly overestimates real precipitation,ithas similar accuracy as V6 when it comes to precipitation event prediction and precipitation spatial distribu-tion. Both products are able to describe the spatial distribution of annual precipitation as well as the tempo-ral and spatial change of areal precipitation with the help of the research on the newly introduced‘precipi-tation centroid＇. In the correction of RT product,RT data is firstly compared to ground gauged precipita-tion on monthly basis and then downscaled to daily basis. The Successive Correction and Optimal Interpola-tion are applied for further handling of the residuals. Satisfying results are obtained from both methods. Asimple distributed hydrological model is driven by the corrected RT products as well as uncorrected onesand ground gauged precipitation. The RT product which has advantage of‘real time＇compared to V6,turns out to be satisfactory,if not better,to be used as model input for stream flow simulation after thecorrection.