The Implications of Surface Heterogeneity and Mesoscale Variability on the Dynamics of Stable Atmospheric Boundary Layers

表面非均质性和中尺度变化对稳定大气边界层动力学的影响

• 批准号: 1026636
• 负责人: Elie Bou-Zeid
• 金额: $ 37.09万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1026636&HistoricalAwards=false
• 关键词: Implications; Surface; Heterogeneity; Mesoscale; Variability

This award provides funding for study of the stable atmospheric boundary layer (SABL), i.e. in situations of stable stratification resisting vertical displacement, with the goal of producing a deeper understanding of the dynamics and structure of turbulent flow and transport within this layer nearest the earth's surface. The researchers plan to accomplish this by exploring how the basic dynamics of the SABL are impacted by surface heterogeneity and mesoscale atmospheric variability. The work will be based on large eddy simulation (LES) type computer modeling using a numerical code and subgrid scale model that have been validated for stable flows. The planned research centers around obtaining answers to four main questions: (1) How is the turbulent kinetic energy (TKE) production-dissipation equilibrium altered by the roughness and thermal heterogeneities of the surface?; (2) Can horizontal transport of TKE produce much higher surface fluxes over areas with strong stability than would be expected under quiescent local conditions?; (3) How does mesoscale variability affect turbulence structure, production and transport in the SABL?; and (4) Do surface heterogeneity and/or mesoscale variability significantly increase SABL TKE levels, can they account for the extra turbulence needed to achieve closure in coarse-mesh (non-LES) models, and how can this information be integrated into such models? To pursue these topics, the researchers will simulate flows under conditions of varying mesoscale forcing and surface roughness characteristics, compute all terms of the TKE budget, and perform a proper orthogonal decomposition of the flow fields. The last step of the analysis will be to simultaneously include both surface heterogeneity and mesoscale variability in such simulations to explore their potential interactions.The intellectual merit of the work is centered on improved representation of idealized and controlled SABL conditions that the planned numerical experiments provide, which will in turn allow the researchers to study the effect of surface heterogeneity and mesoscale variability both separately and concurrently. This approach will allow a qualitative and quantitative understanding of the dynamics associated with these two building blocks on a numerical basis in ways that are extremely challenging to pursue from data-driven field experimental studies.The broader impacts of the research will include the education and training of a post-doctorate researcher and graduate student, as well as involvement of undergraduate and/or high school students in this research through an externally funded program. The work will benefit collaborators who are working to improve the representation of atmospheric boundary layers and land-atmosphere interactions in larger-scale atmospheric models, and potentially be relevant to researchers in fields from pollution dispersion to wind power generation.

该奖项为稳定大气边界层（SABL）的研究提供资金，即在稳定分层抵抗垂直位移的情况下，目的是更深入地了解最接近地球表面的这一层内的湍流和传输的动力学和结构。 研究人员计划通过探索 SABL 的基本动力学如何受到表面异质性和中尺度大气变化的影响来实现这一目标。 这项工作将基于大涡模拟 (LES) 型计算机建模，使用已针对稳定流动进行验证的数值代码和亚网格比例模型。 计划研究的重点是获得四个主要问题的答案：（1）表面粗糙度和热不均匀性如何改变湍流动能（TKE）产生-耗散平衡？ (2) TKE 的水平输运能否在稳定性强的区域产生比静态局部条件下预期高得多的表面通量？ (3) 中尺度变率如何影响SABL中的湍流结构、产生和传输？ (4) 表面异质性和/或中尺度变异是否会显着增加 SABL TKE 水平，它们能否解释在粗网格（非 LES）模型中实现闭合所需的额外湍流，以及如何将这些信息集成到此类模型中？ 为了研究这些主题，研究人员将模拟不同中尺度强迫和表面粗糙度特征条件下的流动，计算 TKE 预算的所有项，并对流场进行适当的正交分解。 分析的最后一步将是在此类模拟中同时包含表面异质性和介观尺度变异性，以探索它们潜在的相互作用。这项工作的智力价值集中于改进计划数值实验提供的理想化和受控 SABL 条件的表示，这反过来将使研究人员能够分别和同时研究表面异质性和介观尺度变异性的影响。 这种方法将允许在数字基础上定性和定量地理解与这两个构建模块相关的动态，而这对于数据驱动的现场实验研究来说是极具挑战性的。该研究的更广泛影响将包括博士后研究员和研究生的教育和培训，以及通过外部资助的项目让本科生和/或高中生参与这项研究。 这项工作将使致力于改善更大规模大气模型中大气边界层和陆地-大气相互作用的表示的合作者受益，并可能与污染扩散和风力发电等领域的研究人员相关。