Air-sea Interaction and Island Geography Impacts on Madden-Julian Oscillation (MJO) Initiation and Propagation Through the MAritime Continent

这项研究的结果将使天气预报和模型开发界受益，并促进与其他科学家的合作。该项目支持一名全日制学生。研究成果将记录在同行评议的出版物中，并通过参加国家和国际讲习班和会议的方式分享。麦登-朱利安涛动（MJO）是一个大尺度的季节内热带扰动（30-50天），伴有对流和环流耦合异常，以大约5米/秒的速度向东传播。MJO影响全球的热带天气，并通过遥相关影响高纬度地区的天气。当MJO加热集中在海洋大陆和西太平洋上空时，温带影响尤为明显。大多数最先进的一般环流模型（GCMs）都难以模拟向东传播的MJO对流，而那些能够模拟的MJO对流在穿越和超越海洋大陆时通常存在困难。将一个仅针对大气的GCM与一个相互作用的海洋模式相结合，通常会改善MJO模拟的幅度、周期性和传播特性，但对于为什么会这样还没有达成共识。本研究将有助于我们进一步认识海气相互作用和海陆地理在MJO模拟中的作用。本研究的预期结果是：1)提高对MJO产生和传播的关键过程的理解；2)对为什么如此多的gcm难以模拟一个能够翻译海洋大陆的向东传播的MJO的新见解。本研究的目的是：1)了解海气相互作用对MJO对流发展的影响机制及其对湿静态能的影响；2)了解海气耦合和海陆地理对MJO传播的相对影响。将分析超参数化群落大气模式（SPCAM）的再分析和模式输出，以评估耦合和非耦合模拟中海气相互作用对MJO对流发展的机制，以及MJO事件在整个海洋大陆传播和不传播的机制。将使用理想岛屿地理进行一系列建模练习，以检验关于海洋大陆对MJO对流及其传播的影响的现有假设。分析方法将应用于一组有限的耦合气候模式，以检查结果在多大程度上依赖于模式。

Results of this research will benefit the weather forecasting and model development communities, and promote collaboration with other scientists. The project supports one full-time student. Research results will be documented in peer-reviewed publications and shared through participation in national and international workshops and conferences.The Madden-Julian oscillation (MJO) is a large-scale intraseasonal (30-50 day) tropical disturbance with coupled convection and circulation anomalies that propagate eastward at about 5 m/s. The MJO impacts tropical weather across the globe, and influences weather at higher latitudes via teleconnections. The extratropical impacts are especially pronounced when MJO heating is centered over the Maritime Continent and West Pacific. Most state-of-the-art general circulations models (GCMs) struggle to simulate eastward-propagating MJO convection, and those that do typically have difficulty with its propagation across and beyond the Maritime Continent. Coupling an atmosphere-only GCM to an interactive ocean model often improves the magnitude, periodicity, and propagation characteristics of its MJO simulation, but there is no consensus as to why this is true. This research will advance our understanding of the roles of air-sea interaction and Maritime Continent geography on the simulation of the MJO. Expected outcomes of this research are 1) improved understanding of processes critical to MJO initiation and propagation and 2) new insights into why so many GCMs struggle to simulate an eastward propagating MJO capable of translating the Maritime Continent. The objectives of this project are 1) to understand the mechanisms of air-sea interaction on MJO convective development and its impact on moist static energy and 2) to understand the relative influences of air-sea coupling and Maritime Continent geography on MJO propagation. Reanalysis and model output from the super-parameterized Community Atmosphere Model (SPCAM) will be analyzed to assess the mechanisms of air-sea interaction on MJO convective development in coupled and uncoupled simulations, and for MJO events that do and do not propagate across the Maritime Continent. A series of modeling exercises using idealized island geography will be performed to test existing hypotheses concerning the Maritime Continent's impact on MJO convection and its propagation. Analysis methods will be applied to a limited set of coupled climate models to examine the extent to which results are model dependent.