Field Observations of Canopy Flows over Complex Terrain
Field Observations of Canopy Flows over Complex Terrain
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DOI：
10.1007/s10546-015-0015-y
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发表时间：
2015-03
影响因子：
4.3
通讯作者：
Eleanor R. Grant;A. Ross;B. Gardiner;S. Mobbs
中科院分区：
文献类型：
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作者：
Eleanor R. Grant;A. Ross;B. Gardiner;S. Mobbs
直到最近，对复杂地形中森林上空和森林内气流的调查一直限于少数建模和实验室研究。在这里，我们提出了一个观测数据集的气流测量内部和上方的森林位于山脊上的阿兰岛，苏格兰。整个山脊上观测的空间覆盖范围使其成为一个独特的数据集。近中性条件下的跨脊流的两个案例研究，并与最近的理想化的二维模拟研究进行比较。平均风和湍流量在整个山脊的冠层廓线的变化与这些理想化的研究大致一致。背风坡上的气流分离被认为是气流的一个普遍特征。然而，地形的三维性质和异质的森林冠层，导致跨山脊的流动分离的显着变化，特别是在不太陡峭的西坡。此外，在流动分离区域中随高度的强定向剪切对雷诺应力项和其他湍流统计具有显著影响。还观察到的是在山顶和背风坡，这在以前的研究中没有看到的风速的变化减少。这个数据集应该为验证真实的复杂地形上的冠层流模型提供有价值的资源。
The investigation of airflow over and within forests in complex terrain has been, until recently, limited to a handful of modelling and laboratory studies. Here, we present an observational dataset of airflow measurements inside and above a forest situated on a ridge on the Isle of Arran, Scotland. The spatial coverage of the observations all the way across the ridge makes this a unique dataset. Two case studies of across-ridge flow under near-neutral conditions are presented and compared with recent idealized two-dimensional modelling studies. Changes in the canopy profiles of both mean wind and turbulent quantities across the ridge are broadly consistent with these idealized studies. Flow separation over the lee slope is seen as a ubiquitous feature of the flow. The three-dimensional nature of the terrain and the heterogeneous forest canopy does however lead to significant variations in the flow separation across the ridge, particularly over the less steep western slope. Furthermore, strong directional shear with height in regions of flow separation has a significant impact on the Reynolds stress terms and other turbulent statistics. Also observed is a decrease in the variability of the wind speed over the summit and lee slope, which has not been seen in previous studies. This dataset should provide a valuable resource for validating models of canopy flow over real, complex terrain.