Document Type : علمی - پژوهشی
Authors
1 Remote sensing& GIS Department,Tarbiat Modarres University , Tehran – Iran
2 Associate professor, Department of Remote Sensing and GIS, Tarbiat Modares University
Abstract
Due to the limitations of real precipitation measurement and the lack of proper spatial and temporal coverage of rainfall measurement in the country, remote sensing technology with high temporal and spatial resolution is considered as a useful tool for estimating the amount of precipitation phenomenon and its temporal and spatial changes; however, satellite data are contaminated to the various errors such as uncertainty in sampling, retrieval errors and inherent errors. Therefore, it is necessary to evaluate the accuracy of their precipitation products before using them. In this study, the effectiveness and accuracy of the precipitation products of CHIRPS, TRMM and MERRA satellites were evaluated using statistical methods against the measured data of 222 synoptic stations located in IRAN on a monthly time scale, for the years 2005-2019. The results showed that the TRMM product with RMSE of 23.84 mm performed better compared to other precipitation products, and after that, the MERRA product with RMSE of 30.57 mm has shown a suitable performance compared to the CHIRPS product with RMSE of 35 mm. Also, the examination of POD, FAR and CSI indices showed that the performance difference of three precipitation products is not considerable and all three have a good performance. In general, the results showed that TRMM satellite products can be used as a good substitute for measured data in where there is no synoptic station. It has also matched in terms of indicators.
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