Studies of Madden-Julian Oscillation (MJO) Initiation Using Atmospheric Sounding Data

该项目包括处理、分析和探索2011-2012年秋季和冬季在印度洋进行的马登-朱利安振荡动力学(发电机)野外活动期间获得的现场数据。马登-朱利安涛动(MJO)是从印度洋传播到太平洋的有组织对流的包络，构成了热带地区季内降水和大气环流变异性的主要形式。MJO影响各种热带天气和气候现象，包括热带气旋(影响墨西哥湾的飓风)、亚洲、澳大利亚、非洲和美洲的季风和降雨量的开始和季节内波动，以及厄尔尼诺事件的开始。在DYNAMO期间观测到了两个完整的MJO周期。该项目的数据来自一个由6个站组成的无线电探空站(气象气球)网络，该网络在迪纳摩期间由PI组织和共同管理，并得到印度洋和西太平洋其他一些优先探空点的加强。该建议的总体目标是利用探空数据，经过一些额外的处理，并与其他迪纳摩观测相结合，检查与MJO生命周期内大气湿度演变有关的过程。初步结果表明，导致这两次MJO事件发生的原因是对流层中低层相对湿度逐渐增加，本项目试图确定导致MJO事件的机制。解决这一问题的一个途径是根据探空数据编制湿度预算，另一个途径是使用活动中的雷达数据来评估各种类型的云对大气增湿的贡献。其他工作将考虑海洋表面温度和非降水云的日循环的作用，以及大气混合层(与下伏海面接触并受到其强烈影响的大气层)深度的变化。尽管MJO很重要，几十年来一直在共同努力，但MJO尚未得到充分解释，全球大气环流模式也难以模拟和预测它。因此，这项研究具有更广泛的社会影响，因为预计它将有助于改善对MJO事件的理解和预测。更具体地说，PI将与世界各地的建模中心合作，以增强MJO预测，最重要的是通过提供数据产品供他们使用，例如用于MJO启动的数值模拟的大尺度强迫场。国际和平研究所注意到，通过他的迪纳摩项目收集的所有无线电探空仪数据都将存放在几个网站上，在这里资助的工作将通过质量控制、消除岛屿效应、解决不均质性等来加强这些数据。

This project consists of processing, analysis, and exploration of field data taken during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign, which took place in the Indian Ocean during the 2011-2012 Fall and Winter seasons. The Madden-Julian Oscillation (MJO) is an envelope of organized convection that propagates from the Indian Ocean to the Pacific Ocean and constitutes the dominant form of intraseasonal precipitation and atmospheric circulation variability in the tropics. The MJO influences a variety of tropical weather and climate phenomena,including tropical cyclones (affecting hurricanes in the Gulf of Mexico), the onset and intraseasonal fluctuations of the monsoons and rainfall over Asia, Australia, Africa, and the Americas, and the onset of El Nino events. Two complete MJO cycles were observed during DYNAMO.Data for this project come from a 6-station network of radiosonde (weather balloon) stations which were organized and co-managed by the PI during DYNAMO, augmented by a number of other Priority Sounding Sites throughout the Indian and Western Pacific Oceans. The overall goal of the proposal is to use the sounding data, after some additional processing and in concert with other DYNAMO observations, to examine the processes associated with the evolution of atmospheric moisture during the MJO lifecycle. Preliminary results show that there was a gradual increase in lower to middle tropospheric relative humidity leading up to the initiation of both MJO events, and this project seeks to identify the mechanisms leading to the build-up. One avenue to address this question is the development of moisture budgets from the sounding data, another is the use of radar data from the campaign to assess the contribution of clouds of various types to atmospheric moistening. Additional work will consider the role of the diurnal cycles of sea surface temperature and non-precipitating clouds, and variations in the depth of the atmospheric mixed layer (the layer of the atmosphere in contact with, and strongly influenced by, the underlying sea surface).Despite its importance and concerted efforts over several decades, the MJO has not yet been adequately explained, and global atmospheric circulation models have difficulty simulating and predicting it. The research thus has societal broader impacts as it is expected to contribute to improved understanding and prediction of MJO events. More specifically, the PI will work with modeling centers around the world to enhance MJO prediction, most importantly by providing data products for their use such as large-scale forcing fields for use in numerical simulations of MJO initiation. The PI notes that all radiosonde data collected through his DYNAMO sub-project will be hosted on several websites, and work funded here would enhance that data through quality control, removal of island effects, resolution of inhomogeneities, etc. In addition, the project provides funding for a graduate student, thereby providing for the future workforce in this research area.