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年秋冬季节在印度洋进行的马登-朱利安振荡（Madden-Julian Oscillation，简称Oscillation）动态实地活动期间采集的实地数据。 马登-朱利安振荡（MJO）是从印度洋传播到太平洋的有组织对流的包络，是热带地区季节内降水和大气环流变率的主要形式。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，非洲和美洲季风和降雨的开始和季节内波动，以及厄尔尼诺事件的开始。该项目的数据来自一个由6个无线电探空仪（气象气球）站组成的网络，该网络在印度洋和西太平洋期间由PI组织和共同管理，并由整个印度洋和西太平洋的一些其他优先探测站点增强。 该提案的总体目标是，在经过一些额外的处理后，并与其他气象观测相结合，使用探空数据来研究MJO生命周期期间与大气湿度演变相关的过程。 初步结果表明，有一个逐渐增加的低到中对流层相对湿度导致两个MJO事件的启动，本项目旨在确定的机制，导致建立。 解决这一问题的一个途径是从探测数据中得出水分收支，另一个途径是利用该运动的雷达数据评估各种类型的云对大气增湿的贡献。 额外的工作将考虑海洋表面温度和非降水云的日周期的作用，以及大气混合层深度的变化（与下伏海面接触并受其强烈影响的大气层）。尽管其重要性和几十年来的共同努力，MJO尚未得到充分解释，全球大气环流模式难以模拟和预测MJO，因此，该研究具有更广泛的社会影响，因为它有望有助于改善对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，以加强MJO预测，最重要的是通过提供数据产品供其使用，例如用于MJO启动数值模拟的大规模强迫场。 PI指出，通过他的CNOO子项目收集的所有无线电探空仪数据将托管在几个网站上，这里资助的工作将通过质量控制，消除岛屿效应，解决不均匀性等来增强数据。

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.