How Atmospheric Synoptic Kelvin Waves Influenced the Propagation of the Madden-Julian Oscillation (MJO)

大气天气开尔文波如何影响马登-朱利安振荡 (MJO) 的传播

• 批准号: 2103624
• 负责人: Paul Roundy
• 金额: $ 48.85万
• 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: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103624&HistoricalAwards=false
• 关键词: How; Atmospheric; Synoptic; Kelvin; Waves

The Madden-Julian Oscillation (MJO) is a large pattern of cloudiness and precipitation that forms over the equatorial Indian Ocean and the adjacent west Pacific and propagates slowly eastward over several weeks. The pattern is an east-west dipole with a region of enhanced cloudiness and rainfall big enough to cover much of the tropical Indian Ocean, accompanied by an equally large region of clear skies and reduced precipitation to the east. The MJO has been called the "holy grail" of tropical meteorology, as 50 years of research to date has not produced a generally accepted explanation for it.The MJO is sometimes called a multiscale phenomenon since its rainy half is best described as an envelope of convection in which various forms of convective aggregation occur. The extent to which the smaller convective disturbances within the MJO envelope affect the large-scale behavior of the MJO is an open question. Work conducted here looks specifically at the extent to which the MJO is influenced by synoptic Kelvin waves, wave disturbances centered on the equator which are smaller than the MJO and propagate through its envelope from west to east. Previous work by the PI shows that the vertical tilt of the Kelvin waves is altered as they move through the convective envelope. The change in tilt may lead to a vertical flux of eddy momentum that contributes to the eastward advance of the MJO. A further mechanism through which Kelvin waves can affect the MJO involves upper-level ridging due to the advection of low potential vorticity air by the Kelvin waves, which could also help move the MJO envelope eastward.The project uses a combination of statistical techniques combined with examination of the moisture and momentum budgets to assess Kelvin wave impacts on the MJO. Datasets to be used include reanalysis products and satellite-based estimates of convective clouds and rainfall. Once the analysis is completed using observational datasets it is repeated for simulations from the Coupled Model Intercomparison Project (CMIP).The work has societal relevance due to the importance of the MJO for long-range weather prediction. The MJO influences weather phenomena around the world including the monsoons of Asia, hurricanes in the Gulf of Mexico, and atmospheric rivers making landfall in the western US. The slow propagation of the MJO means that its effects can, at least in principle, be anticipated well in advance. But the MJO is not well captured in weather and climate models, and work conducted here can directly inform efforts to improve MJO simulation in such models. In particular the work may show the need for better simulation and initialization of Kelvin waves as a key to MJO simulation improvement. The project supports two graduate students, thereby developing the future workforce in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Madden-Julian振荡（MJO）是一种巨大的浑浊和降水模式，在赤道印度洋和邻近的西太平洋上形成，并在几周内缓慢地向东传播。 该模式是一种东西方偶极子，具有增强的云彩和降雨量的区域，足以覆盖印度洋的大部分地区，并伴随着同样大的晴朗天空，并且向东降低了降水量。 MJO被称为热带气象学的“圣杯”，因为迄今为止50年的研究还没有对其进行公认的解释。MJO有时被称为多尺度现象，因为它的雨天最好将其描述为一种对流的封面，在这种对流中发生了各种形式的对流聚集。 MJO包膜内较小的对流干扰影响MJO的大规模行为的程度是一个悬而未决的问题。 这里进行的工作专门研究了MJO受概要开尔文波影响的程度，以比MJO小的赤道上的波动干扰，并通过其信封从西部到东方传播。 PI的先前工作表明，开尔文波的垂直倾斜在对流包膜中移动时会改变。 倾斜的变化可能会导致涡流动量的垂直通量，这导致了MJO的向东前进。 开尔文波可能会影响MJO的进一步机制涉及高层骑行，这是由于开尔文波的潜在涡度空气低的对流，这也可能有助于向东移动MJO封装。该项目结合了统计技术的结合，并结合了对水分和瞬间预算的检查来评估Kelvin Wave Wave Wave Wave on the Mjo的影响。 要使用的数据集包括重新分析产品和基于卫星的对流云和降雨的估计值。 一旦使用观测数据集完成了分析，就会重复使用耦合模型比较项目（CMIP）的模拟。由于MJO在远距离天气预测中的重要性，该工作具有社会相关性。 MJO影响了世界各地的天气现象，包括亚洲的季风，墨西哥湾的飓风以及大气河流在美国西部的登陆。 MJO的缓慢传播意味着至少在原则上可以很好地预期其影响。 但是，MJO在天气和气候模型中没有很好地捕获，此处进行的工作可以直接为改善此类模型中MJO模拟的努力提供信息。 特别是，这项工作可能表明需要更好地模拟和初始化开尔文波作为MJO模拟改进的关键。 该项目支持两名研究生，从而在该研究领域开发了未来的劳动力。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准，被认为值得通过评估来获得支持。