Mechanism and Impacts of Intensifying Madden-Julian Oscillations

马登-朱利安涛动（MJO）是一个在赤道印度洋和西太平洋缓慢向东传播的大尺度对流和环流系统。它调节热带气旋、季风、赤道海洋上的地面风压力，以及可能导致中纬度洪水的大气湿度河。这项研究包括使用最近发展的动力学分析技术和一个新的拉格朗日模型来研究MJO的机制以及它的影响如何随着气候变暖而变化。这项工作将有助于向社会警告MJO的潜在变化以及传统气候模型可能忽略的相关影响。这项工作包括培养和教育一名研究生。各种观测结果表明，MJO在上个世纪，特别是在后半叶有所加剧。大多数气候模式表明，未来MJO的降雨量将继续变大，但在MJO环流是否会进一步加强的问题上，模式存在分歧。这是一个关键问题，因为MJO的许多影响都与它引起的风型扰动有关。在本研究中，研究人员计划：1)开发一种以对流包络为中心的新型观测复合MJO动力结构；2)将观测和模拟的MJO环流划分为Kelvin波和Rossby波分量，并将其与MJO的机制联系起来；3)利用新的拉格朗日模式系统模拟下个世纪MJO变化及其相关影响。这项工作将有助于澄清MJO在自然界和模型中的动态，解释为什么一些模型预测MJO循环加剧，而另一些则没有，并评估MJO变化的潜在影响。该奖项反映了美国国家科学基金会的法定使命，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。

The Madden-Julian Oscillation (MJO) is a large-scale convective and circulation system that propagates slowly eastward over the equatorial Indian and West Pacific Oceans. It modulates tropical cyclones, monsoons, the surface wind stress on equatorial oceans, and atmospheric rivers of moisture that can cause mid-latitude flooding. The research involves using recently developed dynamical analysis techniques and a novel Lagrangian model to study the mechanism of the MJO and how its impacts are likely to change as the climate warms. The work will help warn society about potential changes to the MJO and associated impacts that might be missed by conventional climate models. The work includes the training and education of a graduate student.A variety of observations indicate that the MJO has intensified in the last century, especially in the latter half. Most climate models suggest MJO rainfall will continue to become heavier in the future, but models are divided on the question of whether MJO circulations will further intensify. This is a critical question, because many of the MJO's impacts are related to the perturbations it causes to wind patterns. In this proposal, the researchers plan to: 1) Develop a new observational composite MJO dynamical structure that is centered on its convective envelope; 2) Partition composite observed and modeled MJO circulations into Kelvin and Rossby wave components and relate them to the mechanism of the MJO; and 3) Simulate MJO changes and associated impacts for the next century using a novel Lagrangian modeling system. This work will help to clarify the dynamics of the MJO in nature and in models, provide an explanation for why some models predict intensifying MJO circulations and others do not, and assess potential impacts from a changing MJO.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.