Drying Versus Wettening of the East African Climate

东非气候的干燥与湿润

• 批准号: 1252301
• 负责人: Bradfield Lyon
• 金额: $ 46.71万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1252301&HistoricalAwards=false
• 关键词: Drying; Versus; Wettening; East; African

This project considers changes in East African precipitation during the March to May "long rains" season, which has received less attention in the literature than the October to December "short rains". While the short rains season has stronger interannual variability and stronger links to El Nino, the long rains have experienced a decline between the periods 1999-2009 and 1980-1998. This decadal trend in rainfall has been linked to increasing SST in the Indian Ocean, which in turn has been attributed to anthropogenic climate change. However, climate change simulations from the Coupled Model Intercomparison Project version 3 (CMIP3) show a robust projection that East Africa will become wetter over the 21st century. The climate processes which drive the long rains and their interannual variability are not well understood, and a better understanding of these processes could help to determine whether the model projections are credible, and what factors lead to the dichotomy between long-term model projections and the shorter-term observed trend. The research is divided into three tasks: 1) Identifying the key features of the anomalous large- and regional-scale atmospheric and sea surface temperature (SST) patterns that are linked to observed seasonal rainfall variability and its recent decline in East Africa; 2) Employing climate model simulations and idealized climate model experiments to discern the main drivers of the observed features and changes; and 3) Identifying dynamical and thermodynamical processes in climate model projections associated with changes in long rains precipitation in East Africa during the twenty-first century in the CMIP5 experiments, contrasting results with those found in analysis of CMIP3 experiments.East Africa is one of the most food-insecure regions of the globe, and a better understanding of the causes of drought and the likelihood of future rainfall change could play a critical role for the development of the region. Work under this award will be highly relevant to organizations including the Famine Early Warning Systems Network (FEWSNET) and the International Federation of the Red Cross (IFRC), both of which have close ties to the PIs' home institution. The work thus has important broader impacts in addition to its scientific merit.

该项目考虑了3月至5月“长雨”季节东非降水的变化，与10月至12月“短雨”季节相比，该季节在文献中受到的关注较少。 虽然短雨季的年际变化更强，并且与厄尔尼诺现象的联系也更强，但长雨季在 1999-2009 年和 1980-1998 年期间经历了下降。这种降雨量的十年趋势与印度洋海表温度的增加有关，而印度洋海表温度的增加又归因于人为气候变化。 然而，耦合模型比对项目第 3 版 (CMIP3) 的气候变化模拟显示，东非在 21 世纪将变得更加湿润。 导致长期降雨的气候过程及其年际变化尚不清楚，更好地了解这些过程有助于确定模型预测是否可信，以及哪些因素导致长期模型预测与实际情况之间的二分法。短期观察到的趋势。该研究分为三项任务：1）确定与观测到的东非季节性降雨变化及其近期下降有关的大范围和区域尺度大气和海面温度（SST）异常模式的关键特征； 2）利用气候模型模拟和理想化气候模型实验来辨别观测特征和变化的主要驱动因素； 3) 在 CMIP5 实验中识别与二十一世纪东非长雨降水变化相关的气候模型预测中的动力和热力学过程，并将结果与​​ CMIP3 实验分析中发现的结果进行对比。东非是全球大多数粮食不安全地区，更好地了解干旱的原因和未来降雨量变化的可能性可能对该地区的发展发挥关键作用。 该奖项下的工作将与饥荒早期预警系统网络 (FEWSNET) 和红十字国际联合会 (IFRC) 等组织高度相关，这两个组织都与 PI 所在机构有着密切的联系。 因此，除了科学价值之外，这项工作还具有更广泛的重要影响。