Further Studies on the Meteorology of West and Central Africa

PI将继续对热带非洲的年际和年代际气候变率进行调查。重点是西非，萨赫勒和几内亚海岸地区，以及赤道中部非洲，这是一个对造成气候变异的气象过程知之甚少的地区。这项研究有一个观测部分，依靠过去在观测分析方面的经验和为西非汇编的大量数据集，还有一个建模部分，主要限于线性动力学模型。PI提出了一个新的范式，了解非洲萨赫勒地区的年际和年代际变化，涉及非洲东风急流（AEJ）的纬度位置和赤道西风带的作用，取代向北进入萨赫勒地区的喷气机。要解决的一些关键的相关问题是：（一）AEJ的转变的原因;（二）在西非季风气流中发展深赤道西风急流的原因;（三）急流的两种稳定模式的动力学和能量学的对比。此外，亦会研究热带东风急流、热带辐合带、湿层及东风波活动在年际雨量变率中的作用，这项工作十分重要，因为更深入了解该区的气候变率，有助更准确地预测雨量，而这亦会带来重要的社会效益。

The PI will continue her investigations on interannual and interdecadal climate variability over tropical Africa. The focus is on west Africa, both the Sahel and Guinea Coast regions, and on equatorial Central Africa, a region where meteorological processes contributing to climatic variability are poorly understood. The study has an observational component, relying on past experience in observational analysis and the compilation of extensive data sets for West Africa, as well as a modeling component limited mainly to linear dynamical models. The PI suggests a new paradigm for understanding interannual and interdecadal variability in Sahelian Africa involving the latitudinal position of the African Easterly Jet (AEJ) and the role of the equatorial westerlies in displacing the jet northward into the Sahel region. Some of the key related questions to be addressed are (i) reasons for the shift in the AEJ; (ii) reasons for the development of deep equatorial Westerly jet in the monsoon flow over west Africa; and (iii) contrasts in the dynamics and energetics in the two stable modes of the jet. The role of the Tropical Easterly Jet, the Inter Tropical Convergence Zone, the moist layer and Easterly wave activity in interannual rainfall variability will also be studied.The work is important because better understanding of climate variability over this region will lead to better predictability of rainfall, and this has important societal benefits.