An Evaluation of the Accordance of Modified TRMM Satellite Precipitation Data with Observational Data in the Shapour Basin in the Fars Province

Precipitation is one of the main components of the hydrological cycle, and its data are required for the analysis of meteorological and hydrological models. Due to lack of rainfall data in spatial and temporal scales, this study was performed to evaluate the accuracy of the precipitation estimation by the TRMM Satellite and its modified form in the Shapour Basin in the Fars Province. The daily and hourly rainfall data of the Shapour Basin stations, 28 precipitation events (on an hourly basis), and the daily basic precipitation events (2011–2016) for 5 stations in Boushigan, Kazeroon, Chitti, Arjan, and Posghalat Plains located in the Kazeroon study area were used. The correlation coefficient, the root mean squared error, the probability of detection, the false alarm ratio, and the critical success index were calculated for both rainfall estimations. The results showed that the modified TRMM and TRMM models were not accurate enough on the hourly and daily bases, yet the correlation between the observational data on the hourly basis and the modified TRMM was higher than that of the TRMM. By modifying TRMM rainfall data, the TRMM correlation coefficient improved from 0.52 to 0.75, indicating a relative correlation between the TRMM rainfall data and the ground station data. The correlation coefficient of the estimated precipitation values obtained from the TRMM and TRMM satellites were corrected on a monthly basis, with the ground data at all the studied stations having a high correlation coefficient (greater than 0.85). Correction of the TRMM precipitation data, improved the coefficient of explanation.