Assessment of Ground Station, GPM Satellite and MERRA Precipitation Products in Kashafrud Basin

In recent decades, satellite and model- based precipitation products has attracted attention of the scientists and researchers in hydrology and other disciplines. The purpose of this research is quantitative comparison of MERRA and GPM satellite precipitation products with ground station precipitation values as reference data in Kashafrud basin. The important point about these data is their accuracy and resolution. GPM satellite was launched in February 2014 and up to now there are no studies about these data in Iran and a few studies have been carried out in other countries of the world. This research aims to assess GPM satellite data and MERRA precipitation products in comparison with 34 ground station precipitation data as reference. The assessment carried out in basin and station level and also daily and monthly periods. For validation, the statistical metrics including RMSE, MAE, CC, BIAS, FAR, POD and CSI are used. The results showed that HQ daily precipitation of GPM satellite has higher accuracy than MERRA daily data in this basin and It is in good agreement with ground data and can show the spatial and temporal distribution of rainfall at the basin level. In contrary, MERRA data in monthly temporal scale is superior to GPM data. RMSE values for MERRA in daily basin and station scales are 2.84 and 3.6 and for monthly, 2.8 and 1.74, respectively. For HQ data, RMSE values for daily basin and station scales are 1.78 and 1.72 and for monthly scale, 6.07 and 6.46, respectively.