Abstract:
Rainfall is one of the most important hydrological and climatic elements for many
applications. Satellite/reanalysis rainfall products have recently become an alternative source
to rain gauges and have shown broader application. This study evaluated the performance of
Climate Hazard Group Infrared Precipitation with stations version 2.0 (CHIRPS v2.0) and
Multi-Source Weighted-Ensemble Precipitation version 2.8 (MSWEP v2.8) products against
observed data were evaluated. Rainfall climatology was simulated for different
agroecological zones (AEZs) of Ethiopia for the period 1991-2020 at different temporal
scales ranging from daily to annual. Rainfall occurrence detection capabilities were assessed
using suites of performance evaluation measures, such as the probability of detection (POD),
false alarm ratio (FAR), frequency bias index (FBI), and critical success index (CSI). In
addition, statistical evaluation metrics were used, including mean absolute error (MAE), root
mean square error (RMSE), percent bias (PBIAS), correlation coefficient (r), and Kling
Gupta efficiency (KGE). The result showed that CHIRPS v2.0 is preferable for estimating
monthly, seasonal, and annual rainfall totals, and MSWEP v2.8 for daily rainfall have shown
better performance over all AEZs. The two products display comparable performance for
detecting daily rainfall occurrences over alpine AEZ, but MSWEP v2.8 is superior in the rest
four AEZs. CHIRPS v2.0 outperforms MSWEP v2.8 for detecting most of the daily rainfall
intensity classes over all AEZs. Overall, the two rainfall products can be used for climate
simulation over tropical, subtropical, temperate, and alpine AEZs, but not over the desert
AEZ of Ethiopia. The findings of this study will play a noteworthy role to improve the quality
of hydro-climate studies in Ethiopia. Generally, for both grid-based and station wise national
level studies, I recommend CHIRPS v2.0 for monthly, Bega season, Belg season, Kiremt
season and annual temporal scales and MSWEP v2.8 for daily time step studies.