Connecting Small-scale Humidity Variability to Dynamical Processes Governing Madden-Julian Oscillation Transitions

将小尺度湿度变化与控制 Madden-Julian 振荡转变的动态过程联系起来

• 批准号: 1321891
• 负责人: Paquita Zuidema
• 金额: $ 31.88万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1321891&HistoricalAwards=false
• 关键词: Connecting; Small; scale; Humidity; Variability

This project studies the role of low-level atmospheric moisture in the development of convective clouds associated with the Madden-Julian Oscillation (MJO). The 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 variability in the tropics, and also has important consequences for US weather. The present work is a follow-on to the Dynamics of the MJO (DYNAMO) field campaign, which took place in the equatorial Indian Ocean in 2011-2012 and involved the deployment of radars and other observing assets on Gan Island in the Maldives. One hypothesis of the campaign, also pursued in this project, is that the deep, organized convective clouds associated with MJO initiation develop only when the atmospheric boundary layer, which contains most of the moisture in the atmospheric column, becomes sufficiently deep over a sufficiently large region. The primary task of the present work is to generate humidity datasets using radar and scanning radiometer data collected as part of the campaign, through techniques involving 1) the Bragg scattering of S-band radar signals in cloud-free air; and 2) a combination of radiometer data and the differential attenuation of radar returns from clouds at two wavelengths (S- and Ka-band in this case). The analysis of these humidity products will be complemented by numerical experiments carried out with the Weather Research and Forecasting (WRF) model.The work has broader scientific impacts due to the value new techniques for determining humidity, particularly techniques that can be applied in future field campaigns, as well as the value of the new humidity datasets for the research community. In addition, the work seeks a better understanding of the initiation of MJO, which would be of societal value to the extent that it results in better predictions of the MJO and its downstream consequences. In addition, the work has an educational component, including the use of the datasets in classroom teaching and the support of two graduate students.

本项目研究低层大气水汽在与马登-朱利安振荡(MJO)相关的对流云发展中的作用。MJO是从印度洋传播到太平洋的有组织对流的包层，构成了热带地区季节内降水变化的主要形式，也对美国天气产生了重要影响。这项工作是2011-2012年在赤道印度洋开展的MJO(迪纳摩)实地行动的后续行动，该行动涉及在马尔代夫甘岛部署雷达和其他观测资源。这项运动的一个假设，也是在这个项目中追求的，是只有当包含大气柱中的大部分水分的大气边界层在足够大的区域上变得足够深时，才会形成与MJO启动相关的深层、有组织的对流云。本项工作的主要任务是利用作为宣传活动一部分收集的雷达和扫描辐射计数据生成湿度数据集，所采用的技术涉及：1)S波段雷达信号在无云空气中的布拉格散射；2)辐射计数据和两个波长(在此例中为S和Ka波段)云的雷达回波的差异衰减的组合。对这些湿度产品的分析将得到利用天气研究和预报(WRF)模型进行的数值实验的补充。这项工作具有更广泛的科学影响，因为确定湿度的新技术，特别是可以在未来实地活动中应用的技术，以及新的湿度数据集对研究界的价值。此外，这项工作寻求更好地了解MJO的发起，这将具有社会价值，因为它导致对MJO及其下游后果的更好预测。此外，这项工作还包括教育部分，包括在课堂教学中使用数据集和两名研究生的支持。