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首页> 外文期刊>Journal of Geophysical Research, C. Oceans: JGR >Forced Sahel rainfall trends in the CMIP5 archive
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Forced Sahel rainfall trends in the CMIP5 archive

机译：CMIP5档案库中的萨赫勒强迫降雨趋势

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The simulations of the fifth Coupled Models Intercomparison Project (CMIP5) strengthen previous assessments of a substantial role of anthropogenic emissions in driving precipitation changes in the Sahel, the semiarid region at the southern edge of the Sahara. Historical simulations can capture the magnitude of the centennial Sahel drying over the span of the 20th century and confirm that anthropogenic forcings have contributed substantially to it. Yet, the models do not reproduce the amplitude of observed oscillations at multidecadal timescales, suggesting that either oscillations in the forcing or the strength of natural variability are underestimated. Projections for Sahel rainfall are less robust than the 20th century hindcast and outlier projections persist, but overall the CMIP5 models confirm the CMIP3 results in many details and reaffirm the prediction of a rainy season that is more feeble at its start, especially in West Africa, and more abundant at its core across the entire Sahel. Out of 20 models, four buck this consensus. Idealized simulations from a subset of the CMIP5 ensemble - simulations designed to separate the fast land-atmosphere response to increased greenhouse gases (GHGs) from the slow response mediated through changes in sea surface temperature (SST) - confirm that the direct effect of CO_2 is to enhance the monsoon, while warmer SST induce drying over the Sahel. At the same time, these simulations suggest that the seasonal evolution of the rainfall trends in the scenario simulations, spring drying and fall wetting, is an inherently coupled response, not captured by the linear superposition of the fast and slow response to CO_2. Key PointsAnthropogenic forcing contributed to past drought in the Sahel.Projections are converging on a delay and intensification of the rainy season.land-ocean interactions are important for the response
机译：第五个耦合模型比对项目（CMIP5）的模拟加强了先前对人为排放在驱动撒哈拉沙漠南部边缘的半干旱地区萨赫勒地区降水变化中的重要作用的评估。历史模拟可以捕捉到20世纪整个萨赫勒地区百年干旱的程度，并证实人为强迫对此做出了重大贡献。然而，这些模型并未在多年代际尺度上重现观察到的振荡幅度，这表明强迫振荡或自然可变性强度均被低估了。萨赫勒（Sahel）降雨的预测不如20世纪的后预报好，并且离群值的预测仍然存在，但总体而言，CMIP5模型在许多细节上证实了CMIP3的结果，并重申了对雨季的预测，该雨季的开始更加微弱，尤其是在西非，并且在整个萨赫勒地区的核心地区更为丰富。在20种模型中，有4种违反了这一共识。来自CMIP5集成子集的理想模拟-模拟旨在将对增加的温室气体（GHG）的快速陆地-大气响应与通过海表温度（SST）的变化介导的缓慢响应分开-模拟确认了CO_2的直接作用是增强季风，而更暖的SST则促使萨赫勒地区干燥。同时，这些模拟表明，情景模拟中降雨趋势的季节演变（春季干燥和秋季湿润）是一种固有的耦合响应，不能由对CO_2的快速响应和缓慢响应的线性叠加来捕获。关键点人为强迫导致了萨赫勒地区过去的干旱。预测正集中在雨季的延迟和加剧。陆地-海洋相互作用对于应对

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