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.

该项目研究了低水平大气水分在与Madden-Julian振荡（MJO）相关的对流云中的发展中的作用。 MJO是有组织的对流的信封，从印度洋传播到太平洋，构成了热带地区季节内降水量变异性的主要形式，并且对美国天气也会产生重要的后果。 目前的工作是对MJO（Dynamo）现场运动的动力学的后续作品，该活动于2011 - 2012年在赤道印度洋进行，涉及在马尔代夫甘岛的雷达和其他观察资产的部署。 该活动也在该项目中也提出的一个假设是，与MJO启动相关的深层，有组织的对流云只有当大气边界层（其中包含大气柱中的大部分水分）在足够大的地区变得足够深。 本工作的主要任务是通过涉及1）无云空气中S频段雷达信号的Bragg散射的技术来使用雷达和扫描辐射计的数据来生成湿度数据集； 2）辐射计数据的组合以及在两个波长（在这种情况下在S-和KA波段）处雷达回报的差异衰减。 这些湿度产品的分析将通过天气研究和预测（WRF）模型进行的数值实验来补充。由于确定湿度的价值，尤其是可以在未来的现场活动中应用的技术，以及用于研究社区的新湿度数据集的价值，这项工作具有更大的科学影响。 此外，这项工作正在寻求更好地了解MJO的开始，这将是社会价值的，因为它可以更好地预测MJO及其下游后果。 此外，这项工作还有一个教育组成部分，包括在课堂教学中使用数据集和两名研究生的支持。