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首页> 外文会议>25th Conference on Agricultural and Forest Meteorology and 12th Joint Conference on the Applications of Air Pollution Meteorology with Aamp;WMA and Fourth Symposium on the Urban Environment May 20-24, 2002 Norfolk, Virginia >TURBULENCE STATISTICS AND SPECTRA IN AND ABOVE A HARDWOOD FOREST CANOPY FOR LAGRANGIAN STOCHASTIC MODEL APPLICATIONS
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TURBULENCE STATISTICS AND SPECTRA IN AND ABOVE A HARDWOOD FOREST CANOPY FOR LAGRANGIAN STOCHASTIC MODEL APPLICATIONS

机译：拉格朗日随机模型应用中硬木林冠层内部和上方的湍流统计和光谱

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摘要

To drive a Lagrangian stochastic dispersion model in and over a forest, vertical profiles of turbulence statistics characteristic of a forest environment are needed. In view of this requirement, turbulence measurements were collected in and over a mixed hardwood forest at the University of Michigan Biological Station (UMBS～Flux) in the summer 2000. Vertical velocity and temperature fluctuations were measured at four levels in the canopy, using 1-D sonics and fine wire thermocouples. Three dimensional velocity and temperature fluctuations were available from 3-D sonics at canopy height (H=21,4m) and at 1.6 and 2.1 H on the UMBS～flux tower. Six additional thermocouples were distributed over the canopy layer depth. Vertical profiles of buoyancy flux, mean horizontal velocity, Reynolds stress, standard deviation and skewness of velocity components were calculated. Velocity spectra were computed to explore the potential of estimating the viscous dissipation rate, although preliminary results suggest that the high frequency range of the spectra do not always exhibit the roll-off predicted by Kolmogorov theory. Turbulence statistics profiles and spectra were analyzed and compared in five atmospheric stability classes determined above the canopy (stable, moderately stable, near neutral, moderately unstable, very unstable). The differences among them and their relation to the turbulence motion throughout the canopy is discussed here. The analysis of these measurements will be used to determine a multi-layer parameterization framework of turbulence statistics for implementation in an LSD model for forest canopies. The University of Michigan Biological Station site (45°35' N, 84°42' W) lies in the north of Michigan's lower peninsula in a northern hardwood forest dominated by only five tree species (Schmid et al., 2002). The maximum VAI for 1999 at UMBS was 3.9 +- 0.1 m.
机译：为了在森林内和森林上驱动拉格朗日随机色散模型，需要森林环境特征的湍流统计的垂直剖面。鉴于此要求，2000年夏季在密歇根大学生物站（UMBS〜Flux）的混合硬木林中及其上方收集了湍流测量值。在垂直方向上测量了冠层的四个方向的速度和温度波动，其中使用1 -D超声波和细线热电偶。在UMBS〜通量塔上，三维声波在冠层高度（H = 21.4m）以及在1.6和2.1 H时具有三维速度和温度波动。在冠层的整个深度上分布了六个额外的热电偶。计算了浮力通量，平均水平速度，雷诺应力，标准偏差和速度分量偏度的垂直分布。尽管初步结果表明，频谱的高频范围并不总是显示出由Kolmogorov理论预测的滚降，但仍计算了速度谱以探索估计粘性耗散率的潜力。在顶盖上方确定的五种大气稳定性类别（稳定，中度稳定，接近中性，中度不稳定，非常不稳定）中分析和比较了湍流统计资料和光谱。本文讨论了它们之间的差异以及它们与整个冠层中湍流运动的关系。这些测量值的分析将用于确定湍流统计数据的多层参数化框架，以便在林冠层的LSD模型中实施。密歇根大学生物站址（北纬45°35'，西经84°42'）位于密歇根州下部半岛北部的北部硬木森林中，仅由五种树种主导（Schmid等，2002）。 UMBS在1999年的最大VAI为3.9±0.1 m。

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