Boundary layer characteristics and turbulent exchange mechanisms in highly complex terrain
Boundary layer characteristics and turbulent exchange mechanisms in highly complex terrain
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高度复杂地形的边界层特征及湍流交换机制
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
A. Weiss
中科院分区：
文献类型：
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作者：
M. Rotach;M. Andretta;P. Calanca;A. Weigel;A. Weiss
中尺度高山计划的里维埃拉项目通过将详细的实验活动与高分辨率数值模拟相结合，研究了高山山谷中的湍流结构和相关交换过程。本贡献回顾了有关里维埃拉山谷边界层结构的已发表材料，并讨论了有关近地表湍流结构的新材料。该项目的总体结论是，尽管湍流特征存在很大的空间变异性，并且地形在所有尺度上都具有至关重要的影响，但物理过程仍然可以被准确地理解和建模。然而，许多“教科书特征”，例如山谷和斜坡风系统之间的相互作用或夜间山谷逆温的侵蚀，需要重新考虑，至少对于像里维埃拉山谷这样的小型非理想山谷来说是这样。该项目确定了新的研究领域，例如复杂地形中湍流变量的后处理方法以及平流不可忽略时表面能量平衡的新方法。由于山谷轴线的曲率，山谷大气与自由对流层之间的湿气和热量交换主要由局部“二次”环流主导。由于存在许多弯曲的山谷，并且操作模型的分辨率仍然相当差，因此可能需要对这些过程进行参数化。
The Mesoscale Alpine Programme’s Riviera project investigated the turbulence structure and related exchange processes in an Alpine valley by combining a detailed experimental campaign with high-resolution numerical modelling. The present contribution reviews published material on the Riviera Valley’s boundary layer structure and discusses new material on the near-surface turbulence structure. The general conclusion of the project is that despite the large spatial variability of turbulence characteristics and the crucial influence of topography at all scales, the physical processes can accurately be understood and modelled. Nevertheless, many of the “text book characteristics” like the interaction between the valley and slope wind systems or the erosion of the nocturnal valley inversion need reconsideration, at least for small non-ideal valleys like the Riviera Valley. The project has identified new areas of research such as post-processing methods for turbulence variables in complex terrain and new approaches for the surface energy balance when advection is non-negligible. The exchange of moisture and heat between the valley atmosphere and the free troposphere is dominated by local “secondary” circulations due to the curvature of the valley axis. Because many curved valleys exist, and operational models still have rather poor resolution, parameterization of these processes may be required.