Modelling Canopy Flows over Complex Terrain
Modelling Canopy Flows over Complex Terrain
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DOI：
10.1007/s10546-016-0176-3
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发表时间：
2016-06
影响因子：
4.3
通讯作者：
Eleanor R. Grant;A. Ross;B. Gardiner
中科院分区：
文献类型：
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作者：
Eleanor R. Grant;A. Ross;B. Gardiner
最近的研究流动的森林山丘的动机是一些重要的应用，包括了解CO和其他气体通量的森林在复杂的地形，预测风对树木的损害，并在森林的网站风能潜力建模。目前的建模研究几乎完全集中在高度理想化的，通常完全森林覆盖的山丘上。在这里，我们提出了一个网站上的阿兰岛，苏格兰复杂的地形和异质森林冠层的模型结果。该模型使用显式表示的冠层和1.5阶湍流封闭的冠层内和上方的流动。封闭方案的有效性进行评估，使用湍流数据从现场实验之前比较预测的完整模型与现场观测。对于接近中性的稳定性，结果与观测结果进行了比较，表明这样一个相对简单的冠层模型可以准确地再现在复杂地形和现实的可变森林覆盖上观察到的流型，同时在计算上对于真实的案例研究仍然是可行的。该模型可以更仔细地检查复杂的森林地形上观察到的流动分离。使用粗糙度长度参数化的模型模拟的比较显示出显着的差异，特别是在流动分离，突出需要明确模拟森林冠层，如果需要详细预测森林周围的近地表流动。
Recent studies of flow over forested hills have been motivated by a number of important applications including understanding COand other gaseous fluxes over forests in complex terrain, predicting wind damage to trees, and modelling wind energy potential at forested sites. Current modelling studies have focussed almost exclusively on highly idealized, and usually fully forested, hills. Here, we present model results for a site on the Isle of Arran, Scotland with complex terrain and heterogeneous forest canopy. The model uses an explicit representation of the canopy and a 1.5-order turbulence closure for flow within and above the canopy. The validity of the closure scheme is assessed using turbulence data from a field experiment before comparing predictions of the full model with field observations. For near-neutral stability, the results compare well with the observations, showing that such a relatively simple canopy model can accurately reproduce the flow patterns observed over complex terrain and realistic, variable forest cover, while at the same time remaining computationally feasible for real case studies. The model allows closer examination of the flow separation observed over complex forested terrain. Comparisons with model simulations using a roughness length parametrization show significant differences, particularly with respect to flow separation, highlighting the need to explicitly model the forest canopy if detailed predictions of near-surface flow around forests are required.