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化进行调查。重点是西非，包括萨赫勒和几内亚海岸地区，以及赤道中非，该地区对导致气候变化的气象过程知之甚少。该研究有一个观测部分，依靠过去在观测分析方面的经验和对西非大量数据集的汇编，还有一个建模部分，主要限于线性动力学模型。PI为理解非洲萨赫勒地区的年际和年代际变化提供了一个新的范例，其中涉及非洲东部急流（AEJ）的纬度位置以及赤道西风带在将急流向北置换到萨赫勒地区中的作用。需要解决的一些关键相关问题是：(i) AEJ转变的原因；（ii）西非季风气流中赤道深层西风急流发展的原因；（三）射流两种稳定模态的动力学和能量学对比。本文还将研究热带东风急流、热带辐合带、湿层和东风波活动在降水年际变率中的作用。这项工作很重要，因为更好地了解该地区的气候变化将导致更好的降雨可预测性，这具有重要的社会效益。

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.