Later Wet Seasons with More Intense Rainfall over Africa under Future Climate Change
Later Wet Seasons with More Intense Rainfall over Africa under Future Climate Change
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DOI：
10.1175/jcli-d-18-0102.1
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发表时间：
2018-12-01
影响因子：
4.9
通讯作者：
Allan, Richard P.
中科院分区：
文献类型：
--
作者：
Dunning, Caroline M.;Black, Emily;Allan, Richard P.
由于社会对季节性降雨的高度依赖，非洲降水季节性的变化很可能产生有害的社会经济影响。在这里，我们第一次进行了一个大陆尺度的分析，在RCP4.5和RCP8.5气候预测情景下的湿季特征的变化，在CMIP 5模式的集合使用一个客观的方法来确定的开始和结束的湿季。西非和萨赫勒地区的雨季平均推迟5-10天以上，南部非洲的雨季开始较晚，这与北半球夏末撒哈拉热低压的强度增加和8 - 12月热带雨带位置的北移有关。在RCP 8.5情景下，预计到21世纪末，非洲之角短雨季的降雨量平均将增加100毫米以上。每个雨天的平均降雨量预计将增加，而在降雨量稳定或下降的区域（西部和南部非洲），雨季的降雨天数将减少，中部非洲的降雨量预计将增加，但仍保持不变。适应战略应考虑到雨季缩短、降雨强度增加和降雨频率减少，这将对作物产量和地表水供应产生影响。
Changes in the seasonality of precipitation over Africa have high potential for detrimental socioeconomic impacts due to high societal dependence upon seasonal rainfall. Here, for the first time we conduct a continental-scale analysis of changes in wet season characteristics under the RCP4.5 and RCP8.5 climate projection scenarios across an ensemble of CMIP5 models using an objective methodology to determine the onset and cessation of the wet season. A delay in the wet season over West Africa and the Sahel of over 5-10 days on average, and later onset of the wet season over southern Africa, is identified and associated with increasing strength of the Saharan heat low in late boreal summer and a northward shift in the position of the tropical rain belt over August-December. Over the Horn of Africa rainfall during the short rains season is projected to increase by over 100 mm on average by the end of the twenty-first century under the RCP8.5 scenario. Average rainfall per rainy day is projected to increase, while the number of rainy days in the wet season declines in regions of stable or declining rainfall (western and southern Africa) and remains constant in central Africa, where rainfall is projected to increase. Adaptation strategies should account for shorter wet seasons, increasing rainfall intensity, and decreasing rainfall frequency, which will have implications for crop yields and surface water supplies.