Document Type : Research Paper
Department of Water Science and Engineering, Faculty of Agriculture and Environment, Arak University, Arak, Iran.
, Department of Water Science and Engineering, Faculty of Agriculture and Environment, Arak University, Arak, Iran.
The goal of this study, is to evaluate temporal (monthly) and spatial (in both point scale (40 synoptic stations) and region scale (30 river basins and four climate zones) global propitiation products with observational values in Iran as case study. To this end, first observational data (100 synoptic on a daily scale) and global precipitation products including ERA5, MRRRA2, GLDAS and TERRA (with different spatial resolution on a monthly scale) during the period of 1366-1398, were collected and extracted. Then, the stations and river basins were classified based on aridity index. Statistics criteria's such as coefficient of determination (R2), normalized square root mean square error (NRMSE) and mean oblique error (MBE) were used to compare the data products with observational data. The results of the criteria in point scale showed that the TERRA products in all seasons except summer and in the Hyper-arid, Arid and Semi-arid climate, with an average of 70 precent correlation coefficient higher than 0.5 (R) and 90 precent error rate less than 0.5 (NRMASE) showed a better performance than the rest of the products and in the Humid climate zones of the ERA5 product. In region scale, it also showed that TERRA product in Hyper-arid, ERA5, MRRRA2, GLDAS and TERRA products in Arid climate zones, ERA5 and TERRA products in Semi-arid climate and ERA5, TERRA and MERRA2 showed more suitable efficiency in Humid climate with an average of 80% correlation coefficient higher than 0.5 and 70 precent error rate less than 0.5. Consequently, the TERRA and MERRA2 product in point, region and climate has had good performance.