Comparison of rainfall estimations by TRMM 3B42, MPEG and CFSR with ground-observed data for the Lake Tana basin in Ethiopia

摘要

Planning for drought relief and floods in developing countries is greatlyhampered by the lack of a sufficiently dense network of weather stationsmeasuring precipitation. In this paper, we test the utility of threesatellite products to augment the ground-based precipitation measurement toprovide improved spatial estimates of rainfall. The three products are theTropical Rainfall Measuring Mission (TRMM) product (3B42), Multi-SensorPrecipitation Estimate–Geostationary (MPEG) and the Climate Forecast SystemReanalysis (CFSR). The accuracy of the three products is tested in the LakeTana basin in Ethiopia, where 38 weather stations were available in 2010 witha full record of daily precipitation amounts. Daily gridded satellite-basedrainfall estimates were compared to (1) point-observed ground rainfall and(2) areal rainfall in the major river sub-basins of Lake Tana. The resultshows that the MPEG and CFSR satellites provided the most accurate rainfallestimates. On average, for 38 stations, 78 and 86% of the observedrainfall variation is explained by MPEG and CFSR data, respectively, whileTRMM explained only 17% of the variation. Similarly, the arealcomparison indicated a better performance for both MPEG and CFSR data incapturing the pattern and amount of rainfall. MPEG and CFSR also have a lowerroot mean square error (RMSE) compared to the TRMM 3B42 satelliterainfall. The bias indicated that TRMM 3B42 was, on average, unbiased,whereas MPEG consistently underestimated the observed rainfall. CFSR oftenproduced large overestimates.