Collaborative Research: Evaluating the Roles of Factors Critical to MJO Simulations Using the NCAR CAM3 with Deterministic and Stochastic Convection Parameterization Closures

马登-朱利安涛动（MJO）是一种大尺度降水和大气环流异常模式，形成于印度洋上空，并缓慢向东传播至赤道太平洋中部。地球上大部分地区都能感受到MJO的影响，赤道太平洋中部MJO的存在对墨西哥湾的飓风活动产生了强烈的调节作用。在此资助下开展的工作旨在提高MJO在全球气候模型（GCMs）中的代表性，特别是国家大气研究中心社区大气模型（CAM）。研究中解决的问题集中在被认为对成功模拟MJO至关重要的具体因素上：1)对流动量输送[CMT，发生在积云中]在MJO模拟中有多重要？解决这个问题的目的是了解对流动量输送在伴随mjo的西风爆发中所起的作用。2)对流加热与层状加热、浅对流加热与深对流加热、随机对流关闭与确定性对流关闭在MJO模拟中的作用是什么？目的是确定每个过程如何影响MJO模拟[这里的层状云是指与深积云相关的平坦的上层“砧”]。3)这些角色如何依赖于MJO开发过程中的MJO阶段？回答这个问题的目的是了解每个流程在MJO演进的不同阶段中扮演的角色。这项工作的动机来自于使用天气和气候模式模拟和预测MJO的困难。由于MJO对天气和气候有许多全球性的影响，因此这项工作具有更广泛的影响，因为在模式中更好地表示MJO是生成有用的MJO预报的第一步。此外，MJO是气候模式中对流和云过程参数化的一个重要测试案例，这将增加我们对气候变化的预测和预估的信心。除了这些更广泛的影响之外，该项目还通过本科教学和高中推广活动促进科学教育。

The Madden-Julian Oscillation (MJO) is a large-scale pattern of precipitation and atmospheric circulation anomalies which forms over the Indian Ocean and propagates slowly eastward towards the central equatorial Pacific Ocean. Impacts of the MJO are felt over much of the earth, and the presence of the MJO in the central equatorial Pacific Ocean exerts a strong modulation of hurricane activity in the Gulf of Mexico. Work conducted under this grant is intended to improve the representation of the MJO in global climate models (GCMs), particularly the National Center for Atmospheric Research Community Atmosphere Model (CAM). The questions addressed in the research focus on specific factors believed to be essential to a successful MJO simulation: 1) How important is convective momentum transport [CMT, occurring in cumulus clouds] in the MJO simulation? The objective of addressing this question is to understand what role convective momentum transport plays in westerly wind bursts accompanying MJOs. 2) What are the roles of convective versus stratiform heating, shallow versus deep convection, and stochastic versus deterministic convection closure in the MJO simulation? The objective is to determine how each of the processes affects the MJO simulation [here stratiform refers to the flat, upper-level "anvils" associated with deep cumulus clouds]. 3) How do these roles depend on the MJO phases in the MJO development process? The objective of answering this question is to understand what role each process plays during different stages of the MJO evolution. Motivation for the work comes from the difficulty in simulating and predicting the MJO using weather and climate models.The work has broader impacts due to the many worldwide impacts of the MJO on weather and climate, as better representation of the MJO in models is a first step in generating useful MJO forecasts. In addition, the MJO is an important test case for the parameterization of convection and cloud processes in climate models, which would increase our confidence in predictions and projections of climate change. Beyond these broader impacts, the project also promotes science education through undergraduate teaching and outreach activities to high schools.