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

这个项目是对热带东风波的研究，有两个不同的组成部分。第一部分是研究马登-朱利安涛动（MJO）对非洲东风波（AEWs）的影响。这项研究将集中在PI先前研究的假设上，即MJO影响了非洲东部急流（AEJ）入口处达尔富尔高地地区AEWs的“触发”。这种影响的机制是来自印度洋的mjo诱导的罗斯比波向西传播，它调节了AEJ入口区域的水汽经向输送。第二部分讨论了加勒比海和东太平洋（EP）的东风波活动的起源。以前的研究认为，该地区的东风波实际上是预警波，在穿越大西洋后重新焕发活力。这里的工作将检验另一种假设，即在没有任何跨大西洋预警的“播种”的情况下，该地区有利的基本状态和多个涡度源应该足以产生东风波。在这两个部分进行的工作包括使用天气研究与预报（WRF）模式进行数值实验，WRF是一种区域模式，可以过滤边界条件，以允许或排除传播到模式域的罗斯比波和预警机的影响。热带东风波是热带气旋（包括登陆的飓风）的前兆，因此对重大天气灾害的预测很重要。因此，这项工作通过其与实际天气预报的相关性，具有更广泛的社会影响。此外，这项工作将支持和培训两名研究生，从而为该研究领域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.