Mechanism and Impacts of Intensifying Madden-Julian Oscillations

马登-朱利安振荡（MJO）是一个在赤道印度洋和西太平洋上空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、赤道海洋的表面风应力，以及可能导致中纬度洪水的大气水分河流。该研究涉及使用最近开发的动力学分析技术和一种新的拉格朗日模型来研究MJO的机制以及其影响如何随着气候变暖而变化。这项工作将有助于警告社会关于MJO的潜在变化以及传统气候模型可能错过的相关影响。各种观察表明，MJO在上个世纪，特别是在后半叶得到了加强。大多数气候模型表明，MJO的降雨量将在未来继续增加，但模型在MJO环流是否会进一步加强的问题上存在分歧。这是一个关键问题，因为MJO的许多影响都与它对风模式造成的扰动有关。在这项提案中，研究人员计划：1）开发一种新的观测复合MJO动力学结构，以其对流包络为中心; 2）将观测和模拟的复合MJO环流划分为开尔文和Rossby波分量，并将其与MJO的机制联系起来; 3）使用新的拉格朗日建模系统模拟下一个世纪的MJO变化和相关影响。这项工作将有助于澄清的性质和模型中的MJO的动态，提供了一个解释，为什么有些模型预测加强MJO流通和其他人不，并评估潜在的影响，从一个不断变化的MJO。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.