Study of Atmospheric Turbulence in the Stable Boundary Layer

主要目的是在野外实测和数值模拟的基础上研究稳定分层边界层的结构。为此目的，将对最近两次大气边界层实验所获得的观测结果进行分析。在这些项目中，通过仪器塔和系留提升系统（TLS）收集的湍流数据将被检查。两种数值模型：(i)由a . Kerstein博士开发的一维随机模型，（ii）由首席研究员开发的三维大涡模拟（LES）模型也将被使用。第一个模型将用于模拟在这些项目中观测到的夜间边界层的时间变换。LES模型将用于评估基于梯度的相似函数。该方案的具体目的是系统地改进对稳定分层边界层的理解、描述和参数化。将研究从强稳定湍流到弱稳定湍流的转变。在这些条件下湍流统计的渐近规律将被定义。经典的相似性方法将通过开发和测试新的尺度系统和技术来改进，这将减少尺度缩小和自相关的负面影响。该项目的知识价值在于改进了对夜间边界层过程和制度的理解，目前对这些过程和制度的理解不够充分，而且在目前的大气数值模式中没有得到很好的体现。该项目更广泛的影响是将这种对稳定边界层中的湍流和扩散的改进的概念性理解应用于重要问题。研究结果将通过出版物和在科学会议上的发言来传播。这些结果将用于发展边界层参数化，这在数值天气预报、气候模拟和空气污染研究中是必不可少的。所建立的方法也可应用于对流层湍流的研究

The main objective is to study the structure of the stably stratified boundary layer based on results of field measurements and numerical simulations. For this purpose, observations obtained during two recent atmospheric boundary layer experiments will be analyzed. Turbulence data collected during these projects on instrumented towers and by the Tethered Lifting System (TLS) will be examined. Two numerical models: (i) a one-dimensional stochastic model, developed by Dr. A. Kerstein, and (ii) the three-dimensional large-eddy simulation (LES) model, developed by the principal investigator, will also be used. The first model will be used to simulate the observed temporal transformation in the nocturnal boundary layer during these projects. The LES model will be employed to evaluate gradient-based similarity functions.The specific aim of the proposed program is to systematically improve understanding, description, and parameterization of the stably stratified boundary layer. Investigations will be conducted of transitions from strong to weak stable turbulence. Asymptotic laws for turbulent statistics in these conditions will be defined. The classic similarity approach will be improved by developing and testing new scaling systems and techniques, which will reduce negative effects of diminishing scales and self-correlation.The intellectual merit of the project is improved understanding of processes and regimes in the nocturnal boundary layer, which currently are insufficiently understood and are not well-represented in current numerical models of the atmosphere.The broader impact of the project is application of this improved conceptual understanding of turbulence and diffusion in the stable boundary layer to important problems. Results will be disseminated through publications and presentations at scientific conferences. These results will be used to develop boundary layer parameterizations, which are essential in numerical weather predictions, climate simulations, and air pollution studies. The developed methods could also be applied in studies of tropospheric turbulence