Performance Evaluation of the ERA5, MERRA-2, and PERSIANN-CDR Gridded Products in the Tambo Basin

Gridded meteorological data help to address the scarcity of data in sparse hydrometeorological networks, but their validation is crucial. This study evaluated the performance of ERA5, MERRA-2, and PERSIANN-CDR gridded products in the Tambo basin, comparing their data with meteorological stations and basin-wide averages using the Pearson correlation coefficient (CC), percent bias (PBIAS), and root mean square error (RMSE). PERSIANN-CDR showed the best performance (CC: 0.84–0.94, PBIAS: 6.90–83.10%, RMSE: 21.97–38.78 mm/month). MERRA-2 underestimated precipitation, while ERA5, despite its high correlation (CC: 0.83–0.94), overestimated it. PERSIANN-CDR is the recommended product for the region, providing a better representation of precipitation for hydrological studies and water resource management.