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

大气的最低部分，称为边界层，其特征从白天与频繁的空气运动很好地混合到夜间的稳定和层结状态。然而，尽管夜间边界层总体稳定，但仍有间歇性的湍流气流。这项研究将利用葡萄牙的一项名为Perdigao的大型野外活动来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进数值天气模式，并支持空气质量、航空、风能、交通和气候模拟等关键应用。该项目还将为下一代科学家的教育和培训做出贡献，研究人员将通过各种外展努力为公众的科学素养做出贡献。Perdigao现场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间歇的机制。这将是一项综合的观测和建模工作，由联合国大学提供更多的观测数据。科罗拉多州的博尔德绳索提升系统(TLS)和三个侧面激光雷达。建模组件将使用WRF模型和实施的浸没边界方法(IBM)，以便能够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，在垂直方向上嵌套0.5米。研究人员计划解决以下问题：(I)山谷内部和之上的湍流预算结构，特别是湍流消散率是什么？它如何随着稳定的演变而变化，特别是在稳定的条件下？(Ii)产生湍流间歇性的机制是什么？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？(3)风力机尾迹对相干结构有何影响？这对间歇性有何影响？(4)需要什么样的物理参数和数值技术才能将复杂地形中的中尺度和微尺度模式适当地结合起来？

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?