Modeling Climate Variability and Change of the Greater Horn of Africa

区域尺度上的多种气候驱动因素往往与大尺度气候强迫相互作用，触发、维持甚至放大极端条件。 了解这两个尺度之间的相互作用和反馈，对于确定与区域气候变率和可预测性有关的动力和物理机制的特征十分重要。 大非洲之角（GHA）是一个独特的地区，充满了复杂的地形和其他表面异质性的存在所造成的大型内陆湖泊（维多利亚，坦噶尼喀，马拉维），大裂谷系统，高山（基利曼哈罗，肯尼亚，鲁文佐里），并因此提供了一个有利的设置之间的相互作用大尺度和当地气候系统在各种空间和时间尺度。 因此，这一独特的地理环境对定量了解区域气候变率与单个或组合过程之间的因果关系提出了挑战。 主要研究人员将进行广泛的区域气候模拟相互比较，以评估GHA次区域的区域气候模式性能。 它们将查明和解决区域气候模式中与次优定制和客观参数调整有关的一些缺陷，这些缺陷对于充分模拟区域气候的某些方面至关重要。 他们还将通过一套与赤道印度洋和土地利用模式的海面温度（SST）相关的敏感性实验，调查通过图尔卡纳海峡急流从印度洋输送的水分与埃塞俄比亚西部和苏丹部分地区的气候模式之间的联系，这些地区经常遭受极端干旱的蹂躏。 最后，将制定高分辨率的区域气候变化设想方案，以解决该区域最重要和最脆弱系统的影响评估问题：维多利亚湖和尼罗河流域的水资源。气候变异和变化对粮食生产、水资源和人类健康的后果和影响，在大非洲之角可能比世界任何其他地区都更为不利。 这项研究将有助于我们了解影响GHA气候多尺度变率的中尺度和大尺度过程之间的相互作用。 通过对区域模式性能的弱点和优点进行全面审计，PI将能够根据观察到的区域气候的当地条件改进物理参数化。 改进次季节到年际气候预测将产生巨大的社会效益。 该项目对GHA次区域需求的另一个重要贡献是通过培训一名博士来帮助能力建设。学生. 研究人员还将把他们的模型相互比较结果放在一个公共网页上，其他科学家可以访问这些信息，并提出进一步改进的建议。 此外，他们还将与该区域的主要气候应用中心联系，如位于内罗毕的GHA次区域政府间发展管理局气候预测和应用中心，以便他们能够建立研究应用合作，以便有效传播其成果。

Multiple climate drivers at regional scales often interact with large scale climate forcing to trigger, sustain, and even amplify extreme conditions. Understanding the interactions and feedbacks between the two scales is important for characterization of the dynamical and physical mechanisms associated with regional climate variability and predictability. The Greater Horn of Africa (GHA) is a unique region, replete with complex terrain and other surface heterogeneities imposed by the presence of large inland lakes (Victoria, Tanganyika, Malawi), The Great Rift Valley system, and high mountains (Kilimanjaro, Kenya, Rwenzori), and as such provides a conducive setting for interactions between large scale and local climate systems on various spatial and temporal scales. This unique geographical setting therefore presents challenges in quantitative understanding of cause-effect relationships between regional climate variability and individual or combinations of processes. The principal investigators (PIs) will conduct an extensive regional climate simulation intercomparison to evaluate regional climate model performance over the GHA subregion. They will identify and address some of the deficiencies in regional climate models (RCMs) associated with suboptimal customization and objective parameter adjustments that are critical in the adequate simulation of certain aspects of the regional climate. They will also investigate, through a suite of sensitivity experiments related to sea surface temperatures (SSTs) over the equatorial Indian Ocean and land use patterns, the link between moisture transport from Indian Ocean via the Turkana Channel Jet and climate patterns over parts of western Ethiopia and Sudan, regions often ravaged by extreme droughts. Finally, high-resolution regional climate change scenarios will be developed to address issues of impacts assessment for the most important and vulnerable systems in the region: water resources of Lake Victoria and the Nile Basins. The consequences and impacts of climate variability and change on food production, water resources, and human health are potentially more adverse over the Greater Horn of Africa than in any other part of the world. This research will contribute significantly toward our understanding of the interactions between mesoscale and large scale processes influencing the multi-scale variability of GHA climate. By taking a comprehensive audit of the weaknesses and strength of the performance of the regional models, the PIs will be able to improve the physics parameterizations based on observed local conditions of the regional climate. The societal benefits that would accrue from improved sub-seasonal to inter-annual climate prediction are enormous. Another important contribution of the project to the needs of the GHA sub-region will be to help in capacity building, by training one Ph.D. student. The PIs will also put their model inter-comparison results on a public webpage where other scientists can access the information and make suggestions for further improvement. In addition, they will reach out to the major climate applications centers in the region such as the Intergovernmental Authority for Development Climate Prediction and Applications Center (ICPAC) for the GHA sub-region, located in Nairobi, so that they can establish a research-applications collaboration for the purposes of effective dissemination of their results.