Modeling Climate Variability and Change of the Greater Horn of Africa

University Of Connecticut, Storrs CT

Investigators

Abstract

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.