Studies of the Atmospheric Boundary Layer Using Numerical Simulations Coupled With Radar/Sodar-Based Field Observations

该项目将更全面地描述稳定边界层(SBL)和过渡大气边界层(ABL)的结构、特征和发展。SBL条件的适当表示所固有的概念和计算方面的挑战都将面临。研究人员将使用大涡模拟(LES)计算机模型、虚拟和真实的风廓线仪以及虚拟和真实的喷雾器的组合。具体的焦点将包括从夜间边界层条件过渡到白天边界层条件、地面附近的湍流的产生和低空急流的形成/发展。模拟和观测任务将包括：(1)修改现有的LES程序，以包括适当的次网格闭合方案，以模拟稳定分层的SBL条件和ABL中的过渡(早晚)区域；(2)开发能够探测LES的输出场并产生适合于算法开发和与实际声达操作相关的测试的真实数据流的虚拟声达；(3)综合来自LES和目标雷达/声达观测的数据，以便系统地研究和表征稳定边界层流动和向其他ABL区域的过渡；(4)使用现场传感器、雷达风廓线仪和声纳雷达的资料，进一步修改LES程序，使之适用于SBL和过渡ABL情况，并验证虚拟SOAR的性能。这项工作的主要优点在于改进了对稳定层结边界层和过渡流型的模拟，它们不如对流边界层(CBL)模拟的成熟。互补的风廓线和声达测量使全面捕捉边界层的发展成为可能，当与大涡模拟相结合时，将提供一个独特的机会来调查大涡模拟和其他表征CBL、SBL和两者之间转变的方法的有效性和适用性。这项工作的更广泛的影响包括研究生和本科生的教育和培训，包括与俄克拉荷马大学现有的本科生研究经验(REU-SITE)项目的联系，重点是学生接触现代仪器。在大气层最低层观察和模拟大气条件的改进技术可能会使农业、民用和商业航空以及可再生能源发电的用户社区受益。将加强科学(如气象)和工程(如仪器设计)学科之间的交流。

This project will provide a more comprehensive description of the structure, characteristics, and development of the stable boundary layer (SBL) and transitional atmospheric boundary layer (ABL). Both conceptual and computational challenges inherent in the proper representation of SBL conditions will be confronted. Researchers will use a combination of large-eddy simulation (LES) computer models, virtual and real wind profilers, and virtual and real sodars. Specific foci will include the transition from nighttime to daytime boundary layer conditions, generation of turbulence near the surface, and formation/development of low-level jets. The modeling and observational tasks will encompass (1) modifying an existing LES code to include the appropriate subgrid closure schemes to simulate stably stratified SBL conditions and transitional (morning and evening) regimes in the ABL; (2) developing a virtual sodar capable of probing the output fields of the LES and generating realistic data streams suitable for algorithm development and testing relevant to actual sodar operations; (3) integrating data from LES and targeted radar/sodar observations in order to systematically study and characterize stable boundary layer flows and the transition to other ABL regimes; and (4) using data from in-situ sensors, a radar wind profiler, and a sodar to further adapt the LES code for SBL and transitional ABL cases and validate performance of the virtual sodar.The intellectual merit of this effort lies in the improvement of simulations of the stably stratified boundary layer and transitional flow regimes, which are not as mature as simulations of the convective boundary layer (CBL). Complementary wind profiler and sodar measurements make it possible to comprehensively capture the development of the boundary layer, and when combined with LES modeling will provide a unique opportunity to investigate the effectiveness and applicability of both LES and other means of characterizing the CBL, SBL and transitions between the two.The broader impacts of this work include the education and training of graduate and undergraduate students, including a connection to an existing Research Experience for Undergraduates (REU-Site) program at the University of Oklahoma, with emphasis on student exposure to modern instrumentation. Improved techniques for observing and simulating atmospheric conditions in the lowest layers of the atmosphere will potentially benefit user communities in agriculture, civil and commercial aviation, and renewable energy generation. Enhanced exchange between scientific (e.g., meteorological) and engineering (e.g., instrument design) disciplines will be promoted.