Analyses of Large-scale Extratropical Climate Variability and Change

大范围温带气候变率和变化分析

• 批准号: 1343080
• 负责人: David Thompson
• 金额: $ 73.86万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-01 至 2018-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1343080&HistoricalAwards=false
• 关键词: Analyses; Large; scale; Extratropical; Climate

This project considers the atmospheric circulation in middle and high latitudes of the Northern and Southern Hemisphere, regions referred to as the extratropics. The project has two components, one of which is to improve understanding of the internal variability of the extratropical circulation, and the other is to examine the processes through which thermal forcing drives externally forced north-south shifts in the extratropical storm tracks and their associated eddy fluxes (which occur in part through the air movements associated with frontal weather systems). Research in the first component is based on the premise that large-scale variability in the extratropical flow arises in the context of two primary types of structures: 1) those that dominate the variance of zonal-mean kinetic energy and the conversion between eddy and zonal-mean kinetic energy (which occurs through eddy momentum fluxes); and 2) those that dominate the variance in eddy potential energy and the conversion between zonal-mean and eddy potential energy (which occurs through eddy heat fluxes). In the Southern Hemisphere (SH), which would be the focus of research in the first component, the structure that dominates variance of zonal-mean kinetic energy is the well-known Southern Annular Mode (SAM), which constitutes a north-south shift of the jet stream and accompanying storm track. Research in the second component seeks to understand how the extratropical circulation responds to a variety of external forcings including the depletion of stratospheric ozone (the "ozone hole"), reductions in Arctic snow cover and sea ice extent, increases in greenhouse gases, and solar irradiance. The research addresses the fundamental dynamics which govern the response of jet streams and their attendant storm tracks using simplified atmospheric circulation models, guided by the hypothesis that key aspects of the response can be understood through a diffusive framework in which eddy fluxes of heat and potential vorticity shift to match, in a down-gradient sense, the changes in their respective mean gradients.The work has broader impacts due to the importance of the fundamental dynamics addressed in the project for understanding and predicting the sensible weather and climate experienced at the Earth's surface. In addition, the work will support and train two graduate students from underrepresented groups, thereby broadening participation in the sciences and contributing to the development of the workforce in this research area.

该项目考虑了北半球和南半球中高纬度地区（称为温带地区）的大气环流。该项目有两个组成部分，其一是提高对温带环流内部变化的了解，另一个是研究热强迫驱动温带风暴路径及其相关涡流的外部强迫南北变化的过程通量（部分通过与锋面天气系统相关的空气运动发生）。第一个组成部分的研究基于以下前提：温带气流的大规模变化是在两种主要结构类型的背景下产生的：1）那些主导纬向平均动能的方差以及涡流和纬向之间的转换的结构-平均动能（通过涡动量通量产生）； 2) 那些主导涡流势能的方差以及区域平均和涡流势能之间的转换（通过涡流热通量发生）的因素。在南半球（SH），即第一个分量的研究重点，主导纬向平均动能变化的结构是众所周知的南环模（SAM），它构成了南北偏移急流和伴随的风暴路径。 第二部分的研究旨在了解温带环流如何响应各种外部强迫，包括平流层臭氧消耗（“臭氧空洞”）、北极积雪和海冰范围的减少、温室气体的增加和太阳能的增加。辐照度。 该研究使用简化的大气环流模型解决了控制急流及其伴随的风暴轨迹的基本动力学，其假设是响应的关键方面可以通过扩散框架来理解，其中热涡流和位涡转变以在梯度下降的意义上匹配各自平均梯度的变化。由于该项目中解决的基本动力学对于理解和预测地球表面经历的敏感天气和气候的重要性，这项工作具有更广泛的影响。 此外，这项工作还将支持和培训两名来自代表性不足群体的研究生，从而扩大对科学的参与，并为该研究领域的劳动力发展做出贡献。

项目成果

On the Observed Relationships between Wintertime Variability in Kuroshio–Oyashio Extension Sea Surface Temperatures and the Atmospheric Circulation over the North Pacific

• DOI: 10.1175/jcli-d-17-0343.1
• 发表时间: 2018-05
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Samantha M. Wills;D. Thompson