Journal des sciences de la Terre et du changement climatique

Abstrait

Statistical Evaluation of CORDEX Regional Climate Model?s Performances in Simulating Climate Variables at Upper Awash Basin, Case Study of Akaki Catchment

Bekan Chelkeba Tumsa

The main focus of this study was to investigate and evaluate the Performance of Four Regional Climate Models irrespective of their capability in simulating mean precipitation and Temperature. In this fact and concern, the evaluation of those climate models was basically on how they simulate mean annual climatology, annual cycle and inter annual variability of precipitation, maximum and minimum temperature over the entire catchment. All observed data that used for performance evaluation from 1980-2006 was obtained from Ethiopian National Meteorological Agency and RCM data was extracted from CORDEX-Africa-44 using grid points. RCM show significant bias and almost all of them simulate those climate variables’ at different levels. In the analysis of annual cycle of precipitation during summer season all RCM was underestimated. However, RACMO22T and RCA4 show better adjustment at simulation of both precipitation and Temperatures despite of their significant bias. The bias was deliberately associated with higher error in simulating maximum and minimum temperature at highest topography found at sebeta and Addis Ababa catchments. The interannual variability of precipitations and temperature was shown great evidence where the region is under the impact of climate change specifically when the trend of annual projected temperature shown incremental modality. As far as concern the mean climatology analysis by statistical parameters, almost all models perform nearly equal excluding the seasonal point of view in which RCMs were perform quit differently during season analysis. In all aspects and evidence by statistically evaluated output realize that, RACMO22T and RCA4 were better performed at upper awash catchments although some of their bias and uncertainty were available. Generally, the performance of Regional climate models was different at different catchment along with the specified locations and topographies. Furthermore, the seasonal analysis over Akaki catchment clearly indicates that climate models were more capable of simulate wet season than dry.