TRMM卫星降雨数据的精度及径流模拟评估

Abstract

卫星测雨的精度已成为人们关注的热点，并且在水文研究及应用上有很大的发展前景。本文选取湘江流域为研究区，以地面雨量站点数据为参照，评估了不同时空尺度下热带测雨观测计划(Tropical Rainfall Measuring Mission, TRMM)多卫星降雨分析新产品(TRMM 3B42 V7)的精度，同时分析了精度在不同时期、雨强及高程等因素下的影响规律，并驱动新安江模型展现了径流模拟效果。研究表明：TRMM降水数据与站点数据相关性较好，TRMM数据精度在月尺度明显优于日尺度，流域尺度优于栅格尺度，面雨量精度湿润季节高于干旱季节；雨量估计上TRMM相对站点在流域尺度下整体低估，栅格尺度下受高程影响，在高程较大区域TRMM数据倾向低估，反之倾向高估；各雨强级别下TRMM对小强度降雨稍低估而对强降雨和无雨高估；TRMM数据月径流模拟效果比日径流好，均在可接受范围，但对洪峰、洪量及峰现时间不如站点模拟精准。本研究为TRMM数据的精度订正提供相关思路，并分析其在径流模拟应用中的可行性。 The accuracy of satellite precipitation estimates has become a focus of attention, having a promising prospect in the hydrological researches and applications. In this study, the new precipitation product (3B42 V7) of Tropical Rainfall Measuring Mission (TRMM) was evaluated via comparison with the rain gauge precipitation data in Xiangjiang River Basin. The evaluations were conducted at different spatial and temporal scales. Simultaneously, the laws of data accuracy under different periods, rainfall intensity levels, and elevations were analyzed. These two precipitation data were then adopted to drive the Xinan-jiang Model to perform streamflow simulation. The results showed that TRMM satellite precipitation data had a good correlation with rain gauge precipitation data; it had better accuracy under monthly scale than daily scale and showed better performance at watershed scale than it did at grid scale. The area precipitation of TRMM data showed better accuracy in humid season than in arid season. From an overall estimate on the amount of precipitation, areal precipitation from TRMM data on watershed scale was underestimated in contrast with areal precipitation interpolated from rain gauge data. While at grid scale, TRMM data from higher elevations inclined toward underestimation, while the contrary inclined toward overestimation. The frequency statistical result of different rainfall intensity levels indicated that TRMM tended to underestimate the occurrence of light rainfall intensity but overestimate the occurrence of heavy rainfall intensity and no-rain events. The TRMM-driven streamflow simulation performed better at monthly scale relative to the daily scale, but all were within acceptable range. However, the effects of streamflow simulation driven by TRMM data were not as accurate as those driven by rain gauge data displayed in the aspects of flood peak, flood volume and flood duration. This study assesses the accuracy of the latest product TRMM 3B42 V7, revealing the influential factors regarding accuracy for future reference and analyzing the effectiveness and possibility of streamflow simulation.