Wave Activity Budget and the Variabilities of the Extratropical Climate

波浪活动预算和温带气候的变化

• 批准号: 1563307
• 负责人: Noboru Nakamura
• 金额: $ 70.65万
• 依托单位: University of Chicago
• 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=1563307&HistoricalAwards=false
• 关键词: Wave; Activity; Budget; Variabilities; Extratropical

Upper-level weather charts typically show large-scale wave patterns which are closely associated with the surface fronts, cyclones, and anticyclones that make up daily weather in the middle latitudes. The movements of these waves, and the surface weather patterns connected to them, is driven in large measure by the mean westerly jet streams along which they propagate. The mean jet streams are in turn strongly affected by the behavior of the waves, thus the topic of wave-mean flow interaction is essential for understanding and predicting midlatitude weather. Classical wave-mean flow interaction theory offers powerful insights, but it is based on linear wave dynamics and thus is only formally valid for small amplitude, or infinitesimal, waves. This is a substantial limitation given the waviness of the real-world atmosphere, and the PI has devoted considerable effort to the development of a more general theory which holds for waves of finite amplitude (see AGS-1151790 and AGS-0750916). The present work applies this theory to several topics in atmospheric dynamics, including the 20-30 day oscillation found in the eddy kinetic energy of the Southern Hemisphere storm track (see AGS-1343080). Preliminary work suggests that the oscillation satisfy a wave action conservation relationship and the periodicity is related to wave-induced poleward surface heat flux. Another topic is the dynamics of atmospheric blocking episodes, and a localized version of the wave-mean flow framework is developed to address this problem. Other topics include the roles of boundary layer damping and condensational heating in wave-mean flow interaction. The work is conducted through a combination of analysis of meteorological data (from reanalysis products) and simulations with various configurations of the Community Atmosphere Model (the atmospheric component model of the Community Earth System Model).The work has broader impacts in both a scientific and societal sense, as the conceptual framework developed by the PI can be used by researchers to study a variety of phenomena related to climate variability and change. Further downstream the improved understanding provided by the framework can benefit weather prediction on monthly to seasonal timescales and contribute to better understanding of the results of future climate projections used for decision support. Beyond the benefits of the research itself, the project supports education through a summer school on atmospheric dynamics attended by about 30 graduate students and early career scientists. The summer school includes a combination of lectures, demonstrations, and hands-on activities. In addition, the project supports a graduate student and a postdoc, thereby training the next -generation workforce in this research area.

高层天气图通常显示大范围的波浪模式，这些波浪模式与构成中纬度地区日常天气的地表锋面、气旋和反气旋密切相关。 这些波浪的运动以及与之相关的表面天气模式在很大程度上是由它们传播所沿的平均西风急流驱动的。 平均急流反过来又受到波浪行为的强烈影响，因此波浪与平均流相互作用的主题对于理解和预测中纬度天气至关重要。 经典的波-平均流相互作用理论提供了强有力的见解，但它基于线性波动力学，因此仅在形式上对小振幅或无穷小波有效。 考虑到现实世界大气的波动性，这是一个很大的限制，PI 投入了大量精力来开发适用于有限振幅波的更通用的理论（请参阅 AGS-1151790 和 AGS-0750916）。 目前的工作将该理论应用于大气动力学的几个主题，包括在南半球风暴路径的涡流动能中发现的 20-30 天振荡（参见 AGS-1343080）。初步工作表明，振荡满足波作用守恒关系，并且周期性与波引起的极地表面热通量有关。 另一个主题是大气阻塞事件的动力学，并且开发了波平均流框架的本地化版本来解决这个问题。 其他主题包括边界层阻尼和凝结加热在波平均流相互作用中的作用。 这项工作是通过结合气象数据分析（来自再分析产品）和社区大气模型（社区地球系统模型的大气成分模型）的各种配置的模拟来进行的。这项工作在科学和社会意义，因为研究人员可以使用 PI 开发的概念框架来研究与气候变率和变化相关的各种现象。 在下游，该框架提供的更好的理解可以有利于每月到季节时间尺度的天气预报，并有助于更好地理解用于决策支持的未来气候预测的结果。 除了研究本身的好处之外，该项目还通过约 30 名研究生和早期职业科学家参加的大气动力学暑期学校来支持教育。 暑期学校包括讲座、演示和实践活动。 此外，该项目还支持一名研究生和一名博士后，从而培训该研究领域的下一代劳动力。