Evaluation of CRU TS4.05 and ERA5 Datasets Accuracy to Precipitation, Temperature and Potential Evapotranspiration in Different Climates across Iran

The main objectives of this study was the evaluation of CRU TS4.05 and ERA5 datasets accuracy to monthly precipitation (P), temperature (T) and Potential Evapotranspiration (PET) variables in different climates across Iran. To achieve the research aim, daily measured data from 100 synoptic meteorological stations and monthly P, T and PET products of CRU TS4.05 and ERA5 datasets are used at a spatial resolution of 0.5°×0.5° and 0.25°×0.25° from 1987 to 2019. The mean absolute error values for P, T and PET variables in Hyper-arid (HA), Arid (AR), Semi-arid (SA), Sub-humid (SH) and Humid (HU) climates of CRU TS4.05 datasets are equal to 6, 9, 13, 28 and 81 mm month-1, 1.7, 1.5, 1.8, 2.7, 2.5 oC and 171, 84, 38, 44 and 47 mm month-1, and of ERA5 datasets are equal to 5, 9, 18, 28 and 40 mm month-1, 1.1, 1.6, 1.9, 3.0 and 1.0 oC and 227, 91, 46, 46, 44 and 48 mm month-1, respectively. Results of this study have declared that more accuracy of two datasets (CRU TS4.05 and ERA5) to T, PET and P, respectively. Although, the main results show that accuracy of ERA5 datasets are more than CRU TS4.05 datasets, but it is recommended to use ERA5 P products in SH and HU climates, and CRU TS4.05 PET products in HA and AR climates.