104 A New Look at the Seasonal Cycle of Rainfall in East Africa

Tuesday, 17 April 2018
Champions DEFGH (Sawgrass Marriott)
Sharon E. Nicholson, Florida State Univ., Tallahassee, FL

The seasonal cycle of rainfall over East Africa is typically described as a bimodal rainy season created by the twice-equatorial transit of the ITCZ. This paradigm persists, despite the fact that it is long believed to be wrong be meteorologists working in Africa. This paper re-examines the seasonal cycle over East Africa and shows the fallacy of this scenario. It also describes several factors that do play a role in driving the seasonal cycle. One of these is the low-level Turkana Jet, which appears to have a major influence on rainfall in the region. It is a major factor in the region's prevailing aridity, in interannual variability, and in the lack of a boreal summer rainy season. Understanding the factors controlling the intensity of this jet stream is critical to projecting future climate in the region.
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