Performances of reanalysis products in representing the temperature climatology of Ethiopia

Identifying the most reliable reanalysis temperature products is crucial for advancing hydro-climate research in data-scarce regions. This study evaluated two widely used reanalysis datasets in estimating minimum temperature (Tmin) and maximum temperature (Tmax) across various Agro-Ecological Zones (AEZs) of Ethiopia at different temporal scales over the period 1990 to 2020. These datasets include the Modern-Era Retrospective Analysis for Research and Applications, version 2.0 (MERRA v2.0) and the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5). Evaluations was undertaken at each AEZs using five statistical metrics, scatter plots and line graphs by the data collected from 37 meteorological stations. The results indicate that MERRA v2.0 demonstrates superior performance in simulating Tmin across daily, monthly, and annual temporal scales in most AEZs, based on the majority or entirety of the evaluation metrics. For Tmax, MERRA v2.0 performs best on an annual scale, while ERA5 shows better performance on a daily scale. However, both reanalysis products exhibit comparable performance in estimating monthly Tmax. Notably, the performance of the reanalysis datasets varies across different AEZs. In general, the findings underscore the importance of selecting the most suitable reanalysis datasets for Tmin and Tmax separately, tailored to specific temporal scales and AEZs, to improve hydrology and/or climate studies in data scarce portions of the country.