Evaluation of Areal Monthly Average Precipitation Estimates from MERRA2 and ERA5 Reanalysis in a Colombian Caribbean Basin

Global reanalysis dataset estimations of climate variables constitute an alternative for overcoming data scarcity associated with sparsely and unevenly distributed hydrometeorological networks often found in developing countries. However, datasets require detailed validation to determine their accuracy reliability. This paper evaluates the performance MERRA2 ERA5 regarding monthly rainfall products, comparing areal precipitation averages estimates based on ground measurement records from 49 rain gauges managed by Institute Hydrology, Meteorology, Environmental Studies (IDEAM) Thiessen polygons method Sinu River basin, Colombia. The metrics employed this research are correlation coefficient, bias, normalized root mean square error (NRMSE), Nash–Sutcliffe efficiency (NSE). results show that generally outperforms study area. both reanalyses consistently overestimate calculated IDEAM at all time spatial scales. negative NSE values indicate historical better predictors than products.