Two-dimensional simulation of airflow and carbon dioxide transport over a forested mountain: Part I: Interactions between thermally-forced circulations
Two-dimensional simulation of airflow and carbon dioxide transport over a forested mountain: Part I: Interactions between thermally-forced circulations
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森林山上气流和二氧化碳输送的二维模拟：第一部分：热力环流之间的相互作用
DOI：
10.1016/j.agrformet.2006.03.023
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发表时间：
2006
影响因子：
6.2
通讯作者：
T. A. Black
中科院分区：
文献类型：
--
作者：
Haizhen Sun;T. Clark;R. Stull;T. A. Black
利用一个高分辨率的中尺度模式对一个水平和垂直尺度与温哥华岛相似的理想化二维山区的局地风场进行了研究。然后，将模型生成的流量输出用作erademic数据，以评估涡流协方差（EC）方法中限制性假设的影响，以及Fluxnet-加拿大不列颠哥伦比亚省通量站主塔站点塔通量数据时间过滤的有效性。在本文中，我们描述了模拟的中尺度和局部尺度流态，并在第二部分中，我们描述了他们的使用在评估塔数据分析CO2通量。数值模式增强，包括参数化：树阻力，辐射效应的森林冠层对地表能量收支，土壤热传导。模拟进行了一个理想化的裸露的山丘和森林覆盖的山丘。模拟的流动涉及的陆/海风，对流热气流，和山区环流之间的相互作用，在晴朗的天气条件下。由此产生的模拟风在森林覆盖的斜坡比那些在裸露的斜坡弱得多。由于树顶温度的逆温，森林坡面的夜间排水流被分为冠下和冠上两个区域。最强的下坡流发生在树冠上方，最小速度发生在树冠上方，树冠阻力最强。大对流涡旋在白天的翻转导致了间歇性的下坡流在白天的树冠下。风制度有一个快速的转变，从上坡到下坡流以上的树冠日落后。将使用更高分辨率的3D模拟进行进一步测试。
Local-scale wind regimes over an idealized two-dimensional (2D) mountain having similar horizontal and vertical scales as Vancouver Island were investigated using a high-resolution mesoscale model. The model-generated flow outputs were then used as ersatz data to assess the impact of limiting assumptions in the eddy-covariance (EC) method as well as the effectiveness of tower flux data time-filtering for the main tower site of the Fluxnet-Canada British Columbia flux station. In this paper, we describe the simulated mesoscale and local-scale flow regimes, and in Part II we describe their use in assessing tower-data analyses of CO2fluxes. The numerical model was enhanced to include parameterizations for: tree drag, radiation effects of forest canopies on the surface energy budget, and soil heat conduction. Simulations were performed both over an idealized bare hill and over a forested hill. The simulated flow involved interactions between the land/sea breeze, convective thermals, and mountain circulations under fair-weather conditions. The resulting simulated winds over the forested slope were much weaker than those over a bare slope. The nocturnal drainage flow over the forested slope was separated into sub-canopy and above-canopy regimes due to the temperature inversion at treetop. The strongest downslope flows occurred above the canopy with a minimum velocity occurring in the upper canopy where canopy drag is the strongest. The overturning of large convective eddies during daytime resulted in intermittent downslope flows under the canopy during the day. Wind regimes had a rapid shift from upslope to downslope flow above the canopy just after sunset. Further testing will be made using 3D simulations with higher resolution.