A Modeling Study of Tropical Intraseasonal and Synoptic Variability in West Africa and the Americas

这个项目是一个研究热带东风波有两个不同的组成部分。 第一部分是检查的影响，马登-朱利安振荡（MJO）对非洲东风波（AEWs）。这项研究将侧重于一个假设，该假设是由PI先前的研究所激发的，即MJO影响了非洲东部急流入口处达尔富尔高地地区的AEW的“触发”。这种影响的拟议机制是向西传播的MJO引起的Rossby波从印度洋，调制的AEJ入口区域的水汽纬向输送。第二部分讨论加勒比海和东太平洋东风波活动的起源。以前的研究认为，在这个地区的东风波实际上是AEW，成为后重新跨越大西洋。在这里进行的工作将测试的替代假设，在该地区的有利的基本状态和多个涡度源应足以产生东风波在没有任何“播种”从跨大西洋AEW。 在这两个部分进行的工作包括数值试验与天气研究和预报（WRF）模式，边界条件可以过滤，允许或排除的影响Rossby波和AEW传播到模式域中的区域模式。热带东风波是热带气旋（包括登陆飓风）的前兆，因此是重要的重大天气灾害的预测。因此，这项工作通过其与实际天气预报的相关性而产生了更广泛的社会影响。此外，这项工作将支持和培训两名研究生，从而为这一研究领域的未来劳动力的发展提供支持。

This project is a study of tropical easterly waves with two distinct components. The first component is an examination of the influence of the Madden-Julian Oscillation (MJO) on African Easterly Waves (AEWs). The research would focus on the hypothesis, motivated by the PI's prior research, that the MJO affects the "triggering" of AEWs in the region of the Darfur highlands at the entrance to the African Easterly Jet (AEJ). The proposed mechanism for this influence is the westward propagation of MJO-induced Rossby waves from the Indian Ocean, which modulate the meridional transport of moisture in the AEJ entrance region. The second component addresses the origins of easterly wave activity in the Caribbean Sea and the Eastern Pacific (EP). Previous studies have argued that easterly waves in this region are actually AEWs which become re-invigorated after crossing the Atlantic. Work performed here will test the alternate hypothesis that the conducive basic state and multiple vorticity sources in the region should suffice to generate easterly waves in the absence of any "seeding" from trans-Atlantic AEWs. The work performed in both components consists of numerical experiments with the Weather Research and Forecasting (WRF) model, a regional model in which the boundary conditions can be filtered to allow or exclude the influence of Rossby waves and AEWs propagating into the model domain.Tropical easterly waves are the precursors of tropical cyclones (including landfalling hurricanes), and thus are important for the prediction of significant weather hazards. Thus, the work has societal broader impacts through its relevance for practical weather prediction. In addition, the work will support and train two graduate students, thereby providing for the development of the future workforce in this research area.