East Pacific Easterly Waves: Interactions With Wind Jets in Current and Future Climate

波长约1,000公里的东西移动波是西非、亚热带和热带大西洋、加勒比海和赤道太平洋低纬度地区的重要天气特征。 这些东风波（或EW，意思是从东方移动的波）最为人所知的是飓风的前兆，但它们也是西非、加勒比海和中美洲重要的降雨系统。尽管电子战的重要性，其形成机制和敏感性的环境条件仍然没有完全理解。 东太平洋预警站特别感兴趣的一个问题是它们与中美洲地形的相互作用。 中美洲以其缝隙风而闻名，强风穿过美洲科迪勒拉山脉的缝隙，一个在特万特佩克地峡，另一个在北方哥斯达黎加的帕帕加约湾，第三个通过山脉进入巴拿马湾。首席研究员（PI）以前的工作考虑了差距射流的作用，特别是射流的水平剪切，促进东太平洋EW的产生和振兴EW从加勒比穿越中美洲。 根据该合同进行的工作将使用涡动动能和涡度预算计算来阐明差距射流的影响。 进一步的工作使用计算机模型来研究间隙风的影响，通过创建模拟，其中中美洲地形被人为地改变以填充间隙并阻挡射流。 除了急流和相关风切变对发展中的EW的直接影响外，该项目还考虑了强表面风对海洋表面冷却的潜在影响。 较冷的海表温度（SST）可以抑制对流和降水，这可能会阻碍EWs.Additional工作的发展审查气候变化对间隙流和EWs的影响。 PI最近对气候模型模拟的分析表明，随着世界变暖，帕帕加约湾附近的间隙流将加强，这种加强可能会增强EW的形成。 在这里进行的工作重新审视这个问题，使用区域天气研究和预报（WRF）模式，它可以运行在相当高的分辨率，以更好地解决差距地形和EWs的中尺度动力学。 另一个考虑因素是，预警水可能会从中美洲海岸转移，造成该区域降雨量和水资源可能严重减少。 充分发展的EW的位置的变化可能会受到强烈的影响，太平洋SST趋势的模式，WRF模拟与气候模式模拟共同体地球系统模式（CESM），以解决SST trends.The工作具有社会价值的影响，由于飓风形成的重要性，并作为农业和水资源的降雨天气系统。 此外，PI的小组通过地球系统建模和教育研究所（ESME I）指导本科生暑期实习生，这是科罗拉多州立大学的本科生研究经验（REU）计划。 PI还与美国地球物理联盟的桥梁计划合作，招募来自不同背景的研究生。 该项目为一名研究生提供支持和培训，从而培养该研究领域未来的劳动力。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

East-to-west moving waves with wavelengths of about 1,000km are an important weather feature in the region spanning West Afria, the subtropical and tropical Atlantic, the Caribbean, and the low-latitude equatorial Pacific. These easterly waves (or EWs, meaning waves moving from the east) are best known as the precursors to hurricanes but they are also important rain-bearing systems in West Africa the Caribbean, and Central America. Despite the importance of EWs their formation mechanisms and sensitivities to ambient conditions are still not fully understood. One issue of particular interest for East Pacific EWs is their interaction with the Central American topography. Central America is known for its gap winds, strong winds that funnel through gaps in the American Cordillera, one at the Isthmus of Tehuantepec, another at the Gulf of Papagayo in northern Costa Rica, and a third that channels air through the mountains and into the Panama Bight. Previous work by the Principal Investigator (PI) considered the role of the gap jets, in particular the horizontal shear of the jets, in promoting the generation of East Pacific EWs and reinvigorating EWs which have crossed Central America from the Caribbean. Work conducted under this award would use eddy kinetic energy and vorticity budget calculations to elucidate the effects of the gap jets. Further work uses computer models to study the effects of gap winds by creating simulations in which the Central American topography is artifically altered to fill in the gaps and block the jets. In addition to the direct effects of the jets and associated wind shear on developing EWs the project considers the potential impact of the cooling of the ocean surface by strong surface winds. Cooler sea surface temperatures (SSTs) can inhibit convection and precipitation, which could hinder the development of EWs.Additional work examines the effects of climate change on gap flows and EWs. The PI's recent analysis of climate model simulations suggests that gap flows near the Gulf of Papagayo will strengthen as the world warms, and the strengthening could enhance EW formation. Work conducted here revisits this issue using the regional Weather Research and Forecasting (WRF) model, which can be run at considerably higher resolution to better resolve the gap topography and the mesoscale dynamics of EWs. A further consideration is that EWs may shift away from the Central American coast, causing potentially serious reductions in rainfall and water resources in the region. Changes in the location of fully-developed EWs may be strongly influenced by the pattern of Pacific SST trends, and WRF simulations are used in combination with climate model simulations from the Community Earth System Model (CESM) to address the effects of SST trends.The work has societal value due to the importance of EWs for hurricane formation and as rain-bearing weather systems for agriculture and water resources. In addition, the PI's group mentors undergraduate summer interns through the Earth System Modeling and Education Institute (ESMEI), a Research Experiences for Undergraduates (REU) program at Colorado State University. The PI also works with the Bridge Program of the American Geophysical Union to recruit graduate students from diverse backgrounds. The project provides support and training to one graduate student, thereby developing the future workforce in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.