CAREER: Towards a Better Understanding of Turbulence Structures in a Disturbed Atmospheric Surface Layer

莫宁-奥布霍夫相似理论(MOST)为数值天气和气候模式提供了描述地球表面和低层大气之间的动量、能量、水汽和其他标量的湍流交换的基础。然而，最近的几项研究发现了一些与大多数预测不完全一致的特征，并将这些偏离归因于外层大尺度相干结构(下称相干涡旋)对大气表层局部产生的活跃湍流的扰动。尽管一些研究已经提出了另一种理论来描述这些差异，但对扰动的ASL中的湍流结构仍然知之甚少。本项目的目标是研究对流边界层下稳定和不稳定ASL中的湍流结构，在那里，相干涡旋和活跃湍流之间发生着强烈的相互作用。将使用已经完成的能量平衡实验的数据集。更具体地说，本项目的目标是：1.量化大尺度相干涡旋影响下的湍流结构，并表征在扰动的ASL中白天两种大气层结下的湍流结构与预报的偏差。2.研究相干涡旋如何与ASL湍流相互作用，以及它们对两个大气层结下的动量、热量和水汽通量交换的贡献。3.从ASL的时间序列数据中研究相干涡旋的空间结构和时间演变，以阐明相干涡旋的起源和来源。4.加强杰克逊州立大学微气象实验室，并通过将该项目的研究活动和成果纳入课堂和教学实验室，丰富气象课程。5.吸收大量非裔美国本科生和研究生，鼓励他们参与研究活动。该项目将为本科生和研究生提供绝佳的教育和培训机会，并将极大地加强杰克逊州立大学的大气科学教育，杰克逊州立大学是美国历史上最大的黑人学院和大学之一。

The Monin-Obukhov similarity theory (MOST) provides numerical weather and climate models with a basis in formulating the turbulent exchange of momentum, energy, water vapor, and other scalars between the Earth's surface and the lower atmosphere. However, several recent studies have identified some features that are not fully consistent with predictions by MOST and attributed these departures to the disturbance of outer-layer, large-scale coherent structures (hereafter referred to as coherent eddies) on locally-generated active turbulence in the atmospheric surface layer (ASL). Although some studies have presented alternative theories to describe these discrepancies, turbulence structures in the disturbed ASL are still poorly understood. The objectives of this project are to study turbulence structures in the stable and unstable ASL beneath a convective boundary layer where a strong interaction between coherent eddies and active turbulence occurs. The datasets from the already completed Energy Balance Experiment will be used. More specifically, this project aims to: 1. Quantify turbulence structures under the influence of large-scale coherent eddies and characterize the deviations of turbulence structures from predictions by MOST under two atmospheric stratifications during the daytime in the disturbed ASL. 2. Investigate how coherent eddies interact with the ASL turbulence and their contributions to flux exchange of momentum, heat, and water vapor under two atmospheric stratifications. 3. Study the spatial structures and temporal evolutions of coherent eddies from time-series data in the ASL to elucidate the origins and sources of coherent eddies. 4. Enhance the Jackson State University Micrometeorology Laboratory and enrich meteorological courses through incorporating research activities and findings of this project in the classroom and teaching laboratories. 5. Involve a large number of African American undergraduate and graduate students and encourage them to take part in the research activities. This program will provide an excellent education and training opportunity for undergraduate and graduate students and will greatly enhance atmospheric sciences education in Jackson State University, one of the nation's largest historically black colleges and universities.