P2C2: Extratropical Mechanisms, Land-Surface Properties, and Seasonal Precipitation Processes on Saharan Rainfall and Simulation of the African Humid Period

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This project generally aims to develop an understanding of seasonal non-monsoon processes in order to quantify their contribution to climate change in northern Africa. Specifically, the research aims to provide insights into the relative contributions of the West African Monsoon (WAM), extratropical cyclones, Mediterranean cold air surges, and tropical plumes to African Humid Period (AHP) rainfall (~14,800 - 5,000 years Before Present. At millennial timescales, northern Africa experienced dramatic climate and environmental change. During the early to mid-Holocene AHP, the world's largest present-day hot desert, the Sahara, received abundant rainfall and supported widespread lakes, wetlands, and vegetation. Given the critical role of the present-day Sahara in Earth's radiation budget and its influence on Sahel rainfall, global mineral dust concentrations, biogeochemical cycles, and tropical cyclogenesis, climate variability in the Sahara, such as that observed during the Holocene, has profound impacts on the global climate system. By evaluating the contribution of these processes to AHP rainfall, the research will assist in interpreting the sources of moisture recorded in proxy records from the Sahara-Arabian desert belt which are currently ambiguous because they lie near the border of the tropical monsoon and mid-latitude rainfall regimes. An assessment of the impact of the new dynamic soil albedo scheme within the Community Earth System Model (CESM) will offer tangible insights for climate model development and improved simulation of the AHP. The development of an objective algorithm for the detection of tropical plumes within general circulation models will be made publicly available and could be used to study the processes that influence tropical plume events across the globe in past, present, and future climates.The Broader Impacts involve the potential for increasing the pipeline of underrepresented minority (URM) students into the earth sciences through our participation in the University of Michigan (U-M) Earth Camp. Earth Camp is a residential camp for early-career, high-school students from the Detroit-area that educates them about the earth sciences and careers in the earth sciences. The U-M Earth Camp has consisted of a single summer experience, but is expanding to a multi-summer camp in order to increase the odds that students will study earth sciences in college. As part of our participation in Earth Camp, the participants in this project will develop and instruct a one-day atmospheric science and climate component to the first summer experience in Ann Arbor, MI and create a four-day component for the second summer experience at the U-M field station in Wyoming. In addition to broadening URM participation in the earth sciences, this project will also support the training and career-development of a young scientist and at least one undergraduate student.