Study of Diurnal Transitions in the Atmospheric Boundary Layer

大气边界层的昼夜变化研究

• 批准号: 0400590
• 负责人: Zbigniew Sorbjan
• 金额: $ 26.64万
• 依托单位: Marquette University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0400590&HistoricalAwards=false
• 关键词: Study; Diurnal; Transitions; Atmospheric; Boundary

This project is a study of the atmospheric boundary layer, that layer near the surface of the Earth where turbulent air motions transfer heat, moisture, and momentum between the atmosphere and the Earth. Most past studies have treated this layer as being in a steady state, but transitions occur continually and influence its structure. The boundary layer undergoes a diurnal cycle that moves from a stable nighttime layer through transitional states to a midday convective period and then again through transitional states back to stable nighttime condition. This study will focus on the transition periods and the mid-day convective period. The primary tool to be used is large-eddy simulation (LES), a model technique in which turbulent motions larger than some specified size are represented explicitly while the average influence of the motions at smaller sizes is represented in parameterized form. To complement the LES results, the investigators also will examine observations from a set of well-documented past experiments that have studied the boundary layer in different locations. The expected results will be an extension of knowledge of boundary layer structure to periods of transition and a better understanding of the ways in which transitory turbulence affects that layer.A long-range benefit of this and similar studies will be better representation of the boundary layer in weather and climate models. Such models must represent realistic fluxes of heat, moisture, and momentum between the Earth and the atmosphere but cannot resolve the fine-scale structures responsible for such fluxes. As a result, the fluxes must be represented parameterically in terms of large-scale variables. The development of accurate parametric representations will rely on results from detailed studies like this one. The project will also benefit future work in this area of research by providing training for a graduate student.

该项目是对大气边界层的研究，该层靠近地球表面，湍流空气运动在大气和地球之间传递热量，水分和动量。过去的研究大多将这一层视为处于稳定状态，但过渡不断发生并影响其结构。边界层经历了一个昼夜循环，从一个稳定的夜间层通过过渡状态到中午对流期间，然后再次通过过渡状态回到稳定的夜间条件。本研究将集中在过渡期和中午对流期。要使用的主要工具是大涡模拟（LES），一种模型技术，其中湍流运动大于一些指定的大小表示明确，而在较小的尺寸的运动的平均影响表示在参数化的形式。为了补充LES的结果，研究人员还将检查一组有据可查的过去实验的观测结果，这些实验研究了不同位置的边界层。预期的结果将是边界层结构的知识扩展到过渡时期，并更好地了解瞬态湍流影响该层的方式。这种模式必须代表地球和大气之间真实的热量、水分和动量通量，但不能解决造成这种通量的精细尺度结构。因此，通量必须用大尺度变量的参数表示。精确的参数表示的发展将依赖于像这样的详细研究的结果。该项目还将通过为一名研究生提供培训，使这一研究领域的未来工作受益。