Spatio-temporal evaluation of satellite precipitation products in northwestern Iran

Document Type : Research Paper


1 Water Engineering Dept., Faculty of Agriculture and Natural Resources, member of Water Management Research Center, University of Mohaghegh Ardabili, Ardabil, Iran

2 Department of Water Engineering, College of Aburaihan, University of Tehran, Tehran, Iran

3 Department of Irrigation and Reclamation Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Tehran, Iran



In the analysis of climatic and hydrological events, precipitation is considered as a main parameter and therefore, measuring precipitation data with high Spatio-temporal resolution is very important in predicting weather patterns. Accurate measurement of precipitation on the land surface is very challenging due to the scattering of rain gauge networks, temporal and spatial diversity, wind effects, and topography. In recent decades, the use and development of satellite products and remote sensing techniques have become widespread which is used in precipitation estimation. The aim of this study was to evaluate the satellite precipitation data of TRMM, CHIRPS, Persiann-CDR and GPM-IMERG and compare them with rain gauge data in the north and northwestern region of the country (including Gilan, Ardabil, East Azerbaijan, and West Azerbaijan provinces). Evaluation of the results is performed using definite indicators including POD, CSI, FAR, Bias and statistical criteria including correlation coefficient (Corr) and Normalized Root Mean Square Error (nRMSE). The study period was selected from January 1, 2017 to December 31, 2021 on 56 synoptic stations. The results of most indicators and statistical criteria (Corr, nRMSE, POD, and CSI) showed that in all products the lowest error is related to the southwest of the study area which increases (south of West Azerbaijan province) by moving toward the east of the region and the Caspian coast. In assessing the regional average precipitation, the results of IMERG, CHIRPS and Persiann-CDR were close to each other and with a slight difference (except in the nRMSE criterion) the IMERG product is superior. Also, in the study of seasonal estimates, the results of CHIRPS and Persiann-CDR were more reliable, but in order to use IMERG and TRMM, it is suggested that the estimates be accurized using different error correction methods.


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