Collaborative Research: Perdigao--The Stable Boundary Layer over Complex Terrain

大气层的最低部分，也就是边界层，其特征从白天与频繁的空气运动充分混合到夜间的稳定和分层状态。 然而，尽管夜间边界层总体稳定，但仍有间歇性的湍流空气运动。 这项研究将利用葡萄牙的一个大型实地活动，称为Perdigao，研究复杂地形中的稳定边界层。 更好地了解复杂地形中的湍流和风流将改善数值天气模型，并支持空气质量、航空、风能、交通和气候建模等关键应用。 该项目还将促进下一代科学家的教育和培训，研究人员将通过各种外联工作促进公众的科学素养。Perdigao实地实验是欧洲提高风能生产效率的大型运动的一部分。 该奖项将带来一个基础研究部分，重点是研究复杂地形中稳定边界层中控制湍流不稳定性的机制。 这将是一个综合的观测和建模工作，额外的观测数据由科罗拉多大学在博尔德的系留提升系统（TLS）和三个剖面激光雷达提供。 建模组件将使用WRF模型，并采用浸没边界法（IBM），以便在陡峭的地形表面上进行模拟，模型模拟将能够在水平方向上嵌套5米，垂直方向上嵌套0.5米。 研究人员计划解决以下问题：（i）湍流预算的结构是什么，特别是湍流耗散率，在山谷内和上方？它是如何随着稳定性的演变而变化的，特别是在稳定的条件下？(ii)是什么机制导致了湍流的不稳定性？在大涡模拟中，山谷内和山谷上方的间歇性湍流是如何表现的？(iii)相干结构如何受到风力涡轮机尾流的影响？这是如何影响不情愿的？(iv)在复杂地形中，需要什么样的物理参数化和数值技术来适当地整合中尺度和微尺度模式？

The lowest part of the atmosphere, known as the boundary layer, changes character from being well-mixed with frequent air movement during the day to a nocturnal state of stability and stratification. However, despite the overall stability of the nocturnal boundary layer, there is still intermittent turbulent air movement. This study will leverage a large field campaign effort in Portugal, known as Perdigao, to study the stable boundary layer in complex topography. Better understanding of turbulence and wind flow in complex terrain will improve numerical weather models and support critical applications such as air quality, aviation, wind energy, transportation, and climate modeling. The project will also contribute to the education and training of the next generation of scientists and the researchers will contribute to public literacy of science through various outreach efforts.The Perdigao field experiment is part of a large European campaign to improve the efficiency of wind energy production. This award will bring in a basic research component with a focus on studying the mechanisms controlling turbulence intermittency in stable boundary layers in complex terrain. This will be a combined observational and modeling effort, with additional observational data provided by the Univ. of Colorado at Boulder's Tethered Lifting System (TLS) and three profiling Lidars. The modeling component will make use of the WRF model with an immersed boundary method (IBM) implemented in order to enable simulation over steep terrain surfaces, and the model simulations will be able to nest down to 5m in the horizontal and 0.5m in the vertical. The researchers plan to address the following questions: (i) What is the structure of turbulence budgets, especially turbulence dissipation rate, within and above the valley? How does it change with the evolution of stability, particularly under stable conditions? (ii) What mechanisms generate intermittency of the turbulence? How is the intermittent turbulence within and above the valley represented in large-eddy simulations? (iii) How are coherent structures affected by the wind turbine wake? How does this influence intermittency? (iv) What physical parameterizations and numerical techniques are needed to appropriately integrate mesoscale and microscale models in complex terrain?