Modeling Climate Variability and Change of the Greater Horn of Africa

区域尺度上的多个气候驱动因素往往与大规模气候强迫相互作用，以触发、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描述与区域气候变异性和可预测性有关的动力和物理机制很重要。大非洲之角(GHA)是一个独特的地区，由于内陆大型湖泊(维多利亚、坦噶尼卡、马拉维)、大裂谷系统和高山(肯尼亚乞力马扎罗、鲁文佐里)的存在，地形复杂，地表异质性很大，因此为大尺度和当地气候系统在各种空间和时间尺度上的相互作用提供了有利的环境。因此，这一独特的地理环境对定量理解区域气候变异性与个别过程或过程组合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分区域的区域气候模型表现。它们将查明和解决区域气候模型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。他们还将通过一系列与赤道印度洋海面温度(SST)和土地利用模式有关的敏感性实验，调查经由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情景，以解决该区域最重要和最脆弱的系统：维多利亚湖和尼罗河流域的水资源的影响评估问题。气候多变和变化对粮食生产、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加不利。这项研究将有助于我们理解影响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。通过全面审计区域模式性能的弱点和优势，PIS将能够根据观测到的区域气候的当地条件改进物理参数化。从亚季到年际气候预测的改进将带来巨大的社会效益。该项目对GHA次区域需求的另一个重要贡献将是通过培训一名博士生来帮助能力建设。督导人员亦会把他们的模型比较结果放在一个公众网页上，让其他科学家查阅有关资料，并提出进一步改善的建议。此外，他们还将联系该区域的主要气候应用中心，如设在内罗毕的全球气候评估次区域的政府间发展管理局气候预测和应用中心(ICPAC)，以便它们能够建立研究-应用协作，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.