Climate Change Impacts on Extreme Rainfall in Eastern Africa in a Convection-Permitting Climate Model
Climate Change Impacts on Extreme Rainfall in Eastern Africa in a Convection-Permitting Climate Model
复制标题
在允许对流的气候模型中气候变化对东非极端降雨的影响
DOI：
10.1175/jcli-d-21-0851.1
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发表时间：
2023
影响因子：
4.9
通讯作者：
Chapman S
中科院分区：
文献类型：
--
作者：
Chapman S
气候变化预计将增加极端降雨的频率和强度。了解未来降雨量的变化对于适应规划是必要的。由于适应能力低和未来人口增长率高，东非很容易遭受极端降雨的影响。研究发现，允许对流的气候模型比参数化对流模型更能代表中等（每年）的极端降雨，但对发生频率低于每年一次的罕见极端事件的分析有限。这些事件往往具有最大的社会经济影响。我们使用极值理论和区域频率分析，在对流允许气候模型 (CP4A) 中量化东非罕见的极端降雨。我们将结果与其参数化对应项 (P25)、非洲地区协调区域气候降尺度实验 (CORDEX-Africa) 集合和观测结果进行比较，以了解对流参数化如何影响结果。我们发现 CP4A 比参数化模型更符合观测结果。随着气候变化，我们发现参数化对流模型的极值分布的形状参数发生了不切实际的高变化，它控制着尾部行为（即最极端的事件），导致重现期>20年的事件的重现水平大幅增加。这表明参数化对流模型可能不适合研究罕见降雨事件随气候变化的相对变化，并且对流允许模型应优先用于此类工作。有了更现实的CP4A，RCP8.5世纪末的气候变化导致100年一遇的事件变成23年一遇的事件，这将需要认真的适应努力，以避免毁灭性的社会经济影响。意义声明我们使用一种新的高分辨率气候模型来研究东非罕见的极端降雨事件未来可能如何随气候变化而变化，并将结果与标准分辨率气候模型的结果进行比较。我们发现，对于频率低于每 20 年一次的事件，标准分辨率模型的降雨量增加得不切实际。高分辨率模型更加真实，需要说明罕见降雨极端事件未来可能发生的变化。随着气候变化，极端事件将变得更加普遍，在更现实的模型中，我们表明，如果温室气体排放不显着减少，到本世纪末，100年一遇的事件可能会变成23年一遇的事件。
Climate change is expected to increase the frequency and intensity of rainfall extremes. Understanding future changes in rainfall is necessary for adaptation planning. Eastern Africa is vulnerable to rainfall extremes because of low adaptive capacity and high future population growth. Convection-permitting climate models have been found to better represent moderate (yearly) rainfall extremes than parameterized convection models, but there is limited analysis of rare extremes that occur less frequently than once per year. These events often have the largest socioeconomic impacts. We use extreme value theory and regional frequency analysis to quantify rare rainfall extremes over East Africa in a convection-permitting climate model (CP4A). We compare the results with its parameterized counterpart (P25), the Coordinated Regional Climate Downscaling Experiment for the African region (CORDEX-Africa) ensemble, and observations to understand how the convection parameterization impacts the results. We find that CP4A better matches observations than the parameterized models. With climate change, we find the parameterized convection models have unrealistically high changes in the shape parameter of the extreme value distribution, which controls the tail behavior (i.e., the most extreme events), leading to large increases in return levels of events with a return period of >20 years. This suggests that parameterized convection models may not be suitable for looking at relative changes in rare rainfall events with climate change and that convection-permitting models should be preferred for this type of work. With the more realistic CP4A, RCP8.5 end-of-century climate change leads to 1-in-100-yr events becoming 1-in-23-yr events, which will necessitate serious adaptation efforts to avoid devastating socioeconomic impacts.Significance StatementWe use a new, high-resolution climate model to examine how rare extreme rainfall events in East Africa might change in the future with climate change and compare the results with those from standard-resolution climate models. We find that the standard-resolution models have unrealistically large increases in rainfall for events that occur less frequently than every 20 years. The high-resolution model is more realistic and is required to illustrate possible future changes in rare rainfall extremes. Extreme events will become more common with climate change, and in the more realistic model we show that a 1-in-100-yr event may become a 1-in-23-yr event by the end of the century if greenhouse gas emissions are not significantly reduced.