Madden-Julian Oscillation (MJO) Initiation-DYNAMO (DYNAmics of the Madden-julian Oscillation) and Beyond

马登朱利安振荡 (MJO) 启动 - DYNAMO（马登朱利安振荡动力学）及其他

• 批准号: 1450582
• 负责人: Mohamed Iskandarani
• 金额: $ 51.22万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1450582&HistoricalAwards=false
• 关键词: Madden; Julian; Oscillation; MJO; Initiation

The Madden-Julian Oscillation (MJO) is a disturbance of the tropical atmosphere in which clouds and precipitation are enhanced over a broad region near the equator, with an accompanying region of reduced precipitation and cloudiness to the west or east. MJO events typically begin when convective precipitation breaks out over a large portion of the Indian Ocean, and the region of enhanced precipitation gradually propagates eastward, often as far as the central equatorial Pacific before dissipating. MJO events affect weather and climate over much of the globe, with substantial impacts over the US.A field campaign to study the MJO was conducted in the Indian Ocean From October 2011 to February 2012, titled Dynamics of the Madden-julian Oscillation (DYNAMO; see AGS-1022899). This project is a follow-on to DYNAMO in that it seeks to generalize the results from the DYNAMO campaign to a broader region than the area observed in the campaign, and to MJO events occurring outside the deployment period. It also seeks to use results from the campaign to understand why global weather and climate models have difficulty in simulating the initiation of the MJO.A novel approach taken in this research is to consider MJO initiation as a two stage process, in which the outbreak of widespread convective precipitation is the first stage and the onset of eastward propagation is the second. Previous work shows the existence of non-MJO events, in which precipitation occurs over much of the tropical Indian Ocean but eastward propagation fails to develop. Research under this award attempts to understand why eastward propagation occurs in some cases, resulting in a fully developed MJO event and accompanying global impacts, but not in others. One hypothesis is that propagation of the region of precipitation is initiated by propagating precursor disturbances in atmospheric temperature and winds, which occur independently of the MJO but can interact with the precipitation anomalies to form an eastward moving MJO event.Beyond its scientific interest the work has societal relevance due to the widespread impacts of the MJO. For example, the likelihood of hurricane genesis in the Gulf of Mexico and western Caribbean hurricane genesis is much more likely when the MJO propagates into the central equatorial Pacific, and the MJO is also linked to "atmospheric river" events that bring flooding to coastal California. This work has a direct connection to improving MJO predictions through its emphasis on improving the representation of the MJO in global atmospheric models.

麦登-朱利安涛动（MJO）是热带大气的一种扰动，在赤道附近的广阔地区，云和降水增加，而在西部或东部，降水和云量减少。MJO事件通常开始于印度洋大部分地区出现对流降水，降水增强区域逐渐向东传播，通常远至赤道太平洋中部才消散。MJO事件影响全球大部分地区的天气和气候，对美国有重大影响。2011年10月至2012年2月，在印度洋进行了一项名为“马登-朱利安振荡动力学”（DYNAMO；见AGS-1022899）的实地研究MJO。该项目是DYNAMO的后续项目，旨在将DYNAMO活动的结果推广到更广泛的区域，而不是在活动中观察到的区域，以及在部署期间之外发生的MJO事件。它还试图利用该活动的结果来理解为什么全球天气和气候模型难以模拟MJO的启动。本文提出了一种新的方法，将MJO的形成看作是一个两阶段的过程，其中大范围对流降水的爆发是第一个阶段，向东传播的开始是第二个阶段。以前的工作表明存在非mjo事件，其中降水发生在热带印度洋的大部分地区，但向东传播未能发展。该奖项下的研究试图理解为什么在某些情况下会发生向东传播，导致MJO事件充分发展并伴随全球影响，而在其他情况下则不会发生。一种假设是，降水区域的传播是由传播大气温度和风的前驱扰动引起的，这些扰动独立于MJO发生，但可以与降水异常相互作用，形成向东移动的MJO事件。由于MJO的广泛影响，这项工作除了具有科学意义外，还具有社会意义。例如，当MJO传播到赤道太平洋中部时，墨西哥湾和加勒比海西部飓风形成的可能性更大，MJO也与“大气河”事件有关，这些事件给加利福尼亚沿海带来了洪水。这项工作通过强调改善MJO在全球大气模式中的表现，与改善MJO预测有直接联系。