Document Type : Original Article
Authors
1 PhD student in Agricultural Meteorology, Faculty of Agricultural Engineering, University of Agricultural Sciences and Natural Resources, Sari, Iran
2 Assistant Professor, Department of Agricultural Meteorology, Department of Water Engineering, Faculty of Agricultural Engineering, University of Agricultural Sciences and Natural Resources, Sari, Iran
Abstract
The purpose of this research is to evaluate the accuracy of GPM satellite precipitation products in Mazandaran province. In this regard, the accuracy of satellite precipitation products was compared with weighted interpolation methods of image distance and kriging. For this purpose, the data of 21 meteorological stations and 24 monthly images and 2 annual images of GPM satellite in 2016 and 2018 were used. The evaluation of the methods was done using the mean square error, skew error, and absolute mean error percentage indicators. Also, annual rainfall maps of the province for 2016 and 2018 were drawn and analyzed. The results showed that GPM satellite precipitation products have a high bias error, so that the amount of overestimation/underestimation of this satellite reaches more than 140 mm per year. Of course, the interpolation methods of kriging and weighted image of the distance also have a significant error and do not accurately distinguish between the low and high rainfall rings of the province. Investigating and evaluating the possibility of combining the precipitation products of the desired satellites with latitude and longitude variables and altitude in most of the 4-dimensional gradient equations also showed that the combined Grad-GPM method has significantly increased the accuracy of the spatial estimation of precipitation and the error of interpolation methods. And the satellite reduced the GPM by about 25 to 40 percent. In addition, the examination of precipitation maps also shows the increase in accuracy of combined methods compared to other methods.
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