Collaborative Research: Understanding Interactions between Mesoscale and Microscale Flows in the Stable Boundary Layer over Shallow Terrain

合作研究：了解浅层稳定边界层中尺度流和微尺度流之间的相互作用

• 批准号: 2220662
• 负责人: April Hiscox
• 金额: $ 27.37万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2220662&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Interactions; between

Atmospheric flows under unstable conditions (e.g., sunny days) are better understood than that under stable conditions which often occur at night. If the terrain is not perfectly flat or the surface is vegetated, flows become even more difficult to understand. This uncertainty means nighttime weather forecasts can lack accuracy. This is particularly true in slightly sloping topography as seen through much of the central US. This project will answer fundamental physics questions that exist for stable conditions over much of the planet including: How do plant, terrain, and elevation changes impact atmospheric flows? How do the impacted atmospheric flows interact with flows from other regions? What special flows (like down gully cold air flow; flows colliding) exist in gently sloped areas? This project will use previously collected experimental data to deduce empirical relationships defining when, where, and why these phenomena are likely to occur. This improvement of current theoretical frameworks will further understanding of nighttime pollutant transport and transformation. Public health and safety can benefit from improved quantitative prediction of transport of chemical or biological hazardous pollution. The agricultural community will benefit from increased knowledge of physical processes controlling field-scale temperature, including those affecting crop health and those leading to patches of frost and subsequent crop loss, a major challenge in ensuring global food security. Using unique observations taken during the NSF funded Stable Atmospheric Variability ANd Transport (SAVANT) campaign, this work will lead to an improved understanding of impacts of shallow complex terrain on mechanical and thermodynamic properties of the stable boundary layer and to fill the knowledge gap in scale interactions between environmental and local flows, specifically with respect to flow patterns that occur in shallow topography. SAVANT collected concurrent in-situ and remote sensing observations during two intensive months in the fall of 2018. The field setup was designed to investigate causes and effects of cold air drainage (down gully) flow in a shallow gully. Tracer plume releases tracked with multiple lidar (Light Detection and Ranging) systems offer the unique opportunity to examine interacting flows at multiple spatial scales. Two critical factors for stable-layer turbulent mixing in complex terrain, wind shear and the stable stratification, will be used to stratify observations to describe the most energetic turbulence eddies using the tower data within and above the main gully, augmented by spatial shear observations from lidars. Vertical scaling factors for turbulent eddies and the influences of drainage flows will be investigated. Factors leading to non-uniform drainage flows (i.e., pulsing, meandering, and converging flows) will be detailed. The unique combination of tower and 3-D lidar observations will allow for improved parameterizations of energy and mass exchanges, which will improve predictive model capabilities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

不稳定条件下（例如晴天）的大气流动比经常发生在夜间的稳定条件下的大气流动更容易理解。如果地形不完全平坦或表面有植被，流动就会变得更加难以理解。这种不确定性意味着夜间天气预报可能缺乏准确性。在美国中部大部分地区的略微倾斜的地形中尤其如此。该项目将回答地球大部分地区稳定条件下存在的基本物理问题，包括：植物、地形和海拔变化如何影响大气流动？受影响的大气流量如何与其他地区的流量相互作用？缓坡地区存在哪些特殊气流（如下沟冷气流；气流碰撞）？该项目将使用之前收集的实验数据来推断经验关系，定义这些现象可能发生的时间、地点和原因。对现有理论框架的改进将进一步了解夜间污染物的传输和转化。公共健康和安全可以受益于化学或生物危险污染输送的定量预测的改进。农业界将受益于对控制田间温度的物理过程的更多了解，包括影响作物健康的过程以及导致霜冻和随后作物损失的过程，这是确保全球粮食安全的一项重大挑战。利用 NSF 资助的稳定大气变率和运输 (SAVANT) 活动期间进行的独特观测，这项工作将有助于更好地了解浅层复杂地形对稳定边界层的机械和热力学特性的影响，并填补规模上的知识空白环境流和局部流之间的相互作用，特别是在浅层地形中发生的流型。 SAVANT 在 2018 年秋季的两个月时间里同时收集了现场和遥感观测数据。现场设置旨在研究浅沟壑中冷空气排水（向下沟壑）流动的原因和影响。使用多个激光雷达（光探测和测距）系统跟踪的示踪羽流释放提供了独特的机会来检查多个空间尺度上的相互作用流。复杂地形中稳定层湍流混合的两个关键因素，即风切变和稳定分层，将用于对观测进行分层，以使用主沟内部和上方的塔数据来描述最具活力的湍流涡流，并通过空间切变观测进行增强激光雷达。将研究湍流涡流的垂直比例因子和排水流的影响。将详细介绍导致排水流不均匀（即脉动、蜿蜒和汇聚流）的因素。塔和 3-D 激光雷达观测的独特组合将允许改进能量和质量交换的参数化，从而提高预测模型的能力。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和能力进行评估，被认为值得支持。更广泛的影响审查标准。

项目成果

Exploring influences of shallow topography in stable boundary layers: The SAVANT Field Campaign

探索稳定边界层中浅地形的影响：SAVANT 野外运动

• DOI: 10.1175/bams-d-21-0332.1
• 发表时间: 2023-01
• 期刊: Bulletin of the American Meteorological Society
• 影响因子: 8
• 作者: Hiscox, April;Bhimireddy, Sudheer;Wang, Junming;Kristovich, David A.;Sun, Jielun;Patton, Edward G.;Oncley, Steve P.;Brown, William O.J.
• 通讯作者: Brown, William O.J.