Collaborative Research: A Global View of Topographically Bound Low Level Jets

合作研究：地形限制低空急流的全球视野

• 批准号: 1601628
• 负责人: Scott Fulton
• 金额: $ 32.66万
• 依托单位: Clarkson University
• 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: 2016-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1601628&HistoricalAwards=false
• 关键词: Collaborative; Research; Global; View; Topographically

Topographically bound low-level jets are strong, persistent winds in the lower atmosphere associated with elevated terrain features such as mountain ranges and plateaus. Examples include the persistent northerly and southerly flows on opposite sides of the Rocky Mountains in North America and the Andes Mountains in South America, and the easterly flow that surrounds Antarctica. The goal of this project is to understand what causes these jets and to study their impacts on climate. Previous work developed a two-dimensional theory which explains such jets as a balanced dynamical response of the atmosphere in response to forcing by solar heating and infrared radiative cooling of the elevated terrain. Computed results using simplified terrain profiles showed qualitative agreement with observed winds in two-dimensional cross sections through the Andes and Antarctica. This project will extend the theory to three dimensions, taking into account the effects of the earth's spherical shape and the full shape of the elevated terrain. Solutions of the resulting equations will be computed using a novel numerical method which refines the grid where needed to obtain accurate solutions with minimal computational work. Solutions will be computed for jets associated with several regions of complex terrain around the globe, such as Antarctica, the Tibetan Plateau, Greenland, and the Rockies and Andes, and validated by comparison with observational data.Beyond developing our fundamental understanding of atmospheric dynamics, this work has societal relevance due to the importance of low-level jets for regional climate. For example, the Great Plains low-level jet is responsible for a substantial portion of the moisture transport into the eastern half United States which sustains agriculture, and the low-level jet off the eastern coast of Africa is a major component of the Indian monsoon which greatly affects many aspects of life in the Indian subcontinent. This project will also contribute to developing the future scientific workforce by supporting and training two graduate students in research, and training one undergraduate student in computational mathematics and modern scientific programming. Finally, the methods developed in this project will be made available to researchers in atmospheric dynamics through software codes, so that they can be applied to a wide array of scientific problems.

地形约束的低空急流是低层大气中持续的强风，与山脉和高原等高空地形特征有关。例如，北美落基山脉和南美洲安第斯山脉两侧持续的南北气流，以及环绕南极洲的东风气流。该项目的目标是了解这些喷流的原因，并研究它们对气候的影响。以前的工作发展了一个二维理论，解释了这种急流是大气对太阳加热和高耸地形红外辐射冷却的强迫做出的平衡动力学反应。使用简化地形剖面的计算结果与通过安第斯山脉和南极洲的二维横截面上的观测风质上是一致的。这个项目将把这一理论扩展到三维，考虑到地球的球形和高架地形的完整形状的影响。所得方程的解将使用一种新的数值方法进行计算，该方法在需要时对网格进行细化，以最少的计算工作获得准确的解。将计算与全球几个复杂地形区域(如南极洲、青藏高原、格陵兰、落基山脉和安第斯山脉)相关的急流的解，并通过与观测数据的比较来验证。由于低空急流对区域气候的重要性，这项工作不仅发展了我们对大气动力学的基本理解，而且具有社会意义。例如，大平原低空急流负责向美国东部输送相当大一部分水汽，维持农业；非洲东海岸的低空急流是印度季风的主要组成部分，它极大地影响了印度次大陆生活的许多方面。该项目还将通过支持和培训两名研究生的研究工作，以及培训一名计算数学和现代科学编程的本科生，为发展未来的科学队伍作出贡献。最后，这个项目中开发的方法将通过软件代码向大气动力学的研究人员提供，以便它们可以应用于广泛的科学问题。