Abstract This study was targeted at evaluating the performance of six Regional Climate Models (RCMs) used in Coordinated Regional Climate Downscaling Experiment (CORDEX). The evaluation is on the bases of how well the RCMs simulate the seasonal mean climatology, interannual variability and annual cycles of rainfall, maximum and minimum temperature over two catchments in western Ethiopia during the period 1990–2008. Observed data obtained from the Ethiopian National Meteorological Agency was used for performance evaluation of the RCMs outputs. All Regional Climate Models (RCMs) have simulated seasonal mean annual cycles of precipitation with a significant bias shown on individual models; however, the ensemble mean exhibited better the magnitude and seasonal rainfall. Despite the highest biases of RCMs in the wet season, the annual cycle showed the prominent features of precipitation in the two catchments. In many aspects, CRCM5 and RACMO22 T simulate rainfall over most stations better than the other models. The highest biases are associated with the highest error in simulating maximum and minimum temperature with the highest biases in high elevation areas. The rainfall interannual variability is less evident in Finchaa with short rainy season experiencing a larger degree of interannual variability. The differences in performance of the Regional Climate Models in the two catchments show that all the available models are not equally good for particular locations and topographies. In this regard, the right regional climate models have to be used for any climate change impact study for local-scale climate projections.

中文翻译：

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CORDEX 区域气候模型在模拟上青尼罗河流域两个流域气候条件方面的性能评估

摘要 本研究旨在评估用于协调区域气候降尺度实验 (CORDEX) 的六个区域气候模式 (RCM) 的性能。评估基于 RCM 对 1990 年至 2008 年期间埃塞俄比亚西部两个流域的季节性平均气候、年际变率和年降雨周期、最高和最低温度的模拟情况。从埃塞俄比亚国家气象局获得的观测数据被用于 RCM 输出的性能评估。所有区域气候模型 (RCM) 都模拟了降水的季节性平均年度周期，个别模型显示出显着偏差；然而，集合平均值表现出更好的幅度和季节性降雨量。尽管 RCM 在雨季的偏差最大，年循环显示两个流域的降水特征突出。在许多方面，CRCM5 和 RACMO22 T 比其他模型更好地模拟了大多数站点的降雨量。在高海拔地区模拟最高和最低温度时，最高偏差与最高误差相关。Finchaa 的降雨年际变化不太明显，短雨季经历了较大程度的年际变化。两个流域中区域气候模型的性能差异表明，所有可用模型对于特定位置和地形的效果并不相同。在这方面，必须使用正确的区域气候模型来进行任何气候变化影响研究，以进行局部尺度气候预测。