植物冠层动量交换特征的实验研究

An Experimental Study on Exchange Characteristics of Momentum in the Plant Canopy Layer

使用湍流梯度测试资料，对植物冠层动量交换特征进行了详细研究，结果表明；森林冠层内惯性副区能谱曲线仍可用幂指数描述，但斜率比－２／３更负；森林冠层内湍流尺度有变小的趋势；森林上层的耗散系数比下层大；由植被吸收引起动量及动量通量随冠层深度增加而明显减小；冠层下层的动量通量和耗散系数分别与上层的量有好的正相关；森林冠层内耗散系数和动量通量随大气稳定度有明显变化。

Using observational data of the turbulent gradient, exchange characteristics of the momentum in the plant canopy layer (CL) are studied in detail. The results reveal that the power spectrum curve in the inertial subrange for the forest CL can be expressed by a power law, but the power exponential is less than -2/3; turbulent scale in the forest CL tends to decrease; the dissipation coefficient in the upper forest CL is greater than that in the lower forest CL; momentum and momentum flux decrease with the increase of the CL depth due to absorbtion of momentum by the plant; the momentum flux and dissipation coefficient in the lower CL are positive correlated obviously with the corresponding variables in the upper CL. Variations of the dissipation coefficient and momentum flux with atmospheric stability are found within forest CL.