Intraseasonal Extratropical Precursors to the Indian Ocean Madden-Julian Oscillation (MJO) Proximate to Africa

靠近非洲的印度洋马登-朱利安涛动 (MJO) 的季节内温带前兆

• 批准号: 1560627
• 负责人: Paul Roundy
• 金额: $ 48.64万
• 依托单位: SUNY at Albany
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1560627&HistoricalAwards=false
• 关键词: Intraseasonal; Extratropical; Precursors; Indian; Ocean

The Madden-Julian Oscillation (MJO) is a large envelope of clouds and precipitation that forms over the Indian Ocean and slowly propagates eastward to the middle of the equatorial Pacific. It affects weather conditions worldwide including atmospheric rivers and flooding in California and hurricane formation in the Gulf of Mexico. Some MJO events appear to form independently and are designated as "primary" events. Other "secondary" events appear to be triggered by wave disturbances in the upper troposphere which propagate into the Indian Ocean from regions to the west, in the subtropical belts of the Northern and Southern Hemispheres. The triggering of MJO events by upstream wave disturbances has been well documented, but the processes through which the waves induce MJO events are not well known, and this project seeks to better understand them. Preliminary work by the PI suggests that the precursor waves are not fast moving triggers that impulsively kick-start the MJO, but slowly propagating Rossby waves with intraseasonal timescales. One possibility is that a secondary MJO events can be promoted by an earlier MJO event, which generates Rossby waves in the central equatorial Pacific which propagate eastward and toward higher latitudes, later recurving back into the tropics where they arrive over the equatorial Indian Ocean to induce the subsequent MJO. The project has a focus on Africa because the precursor waves enter the Indian Ocean from the African subtropics. A variety of statistical methods are used to detect and characterize the precursor waves, which are identified in observational data from satellites as well as reanalysis products. Moisture and momentum budgets are then used to understand how the waves contribute to the formation of secondary MJO events.The work has societal broader impacts due to the variety of weather impacts associated with the MJO. There is some skill in forecasts of the propagation of MJO events, but predictions of the initiation of MJO events would allow greater lead times for prediction of MJO impacts. As the project focuses on precursor meteorology over Africa, the project may also have benefit for understanding and predicting African weather. In addition, the project provides support and training to two graduate students, thereby building the future workforce in this research area.

Madden-Julian振荡（MJO）是云层和降水的大信封，在印度洋上形成，并慢慢向东传播到赤道太平洋的中间。 它影响了全世界的天气状况，包括大气河流和加利福尼亚州的洪水以及墨西哥湾飓风地层。 一些MJO事件似乎是独立形成的，并被指定为“主要”事件。 其他“次要”事件似乎是由对流层上部的波浪扰动引起的，这些波浪扰动从北半球和南半球的亚热带带传播到印度洋。 上游波浪干扰触发MJO事件的触发已得到充分记录，但是波浪引起的MJO事件的过程并不众所周知，并且该项目旨在更好地理解它们。 PI的初步工作表明，前体波并不是快速移动的触发器，它冲动启动了MJO，而是在季节内时慢慢地传播Rossby波。 一种可能性是，可以通过较早的MJO事件来促进次级MJO事件，该事件在中央赤道太平洋中产生了罗斯比波浪，该事件向东和更高的纬度传播，后来又转移回热带地区，在那里它们越过赤道印度洋以诱导后续的MJO。 该项目专注于非洲，因为前体波从非洲亚热带进入印度洋。 使用多种统计方法来检测和表征前体波，这些波浪在卫星的观察数据和重新分析产物中被鉴定出来。 然后，使用水分和动量预算来了解波浪如何促进次级MJO事件的形成。由于与MJO相关的天气影响的多样性，这项工作对社会产生了更广泛的影响。 在对MJO事件的传播的预测方面有一定技巧，但是对MJO事件的启动的预测将使预测MJO影响的提前时间更大。 由于该项目着重于非洲的先驱气象学，因此该项目也可能有利于理解和预测非洲天气。 此外，该项目为两名研究生提供支持和培训，从而在该研究领域建立了未来的员工队伍。