长白山森林下垫面湍流谱特征研究

Turbulence Structure Characteristics Within and Above Changbai Mountain Forest

利用2003年5月27日、28日在长白山原始森林冠层2个不同高度上观测的湍流资料,采用通量处理软件Eddypro计算和分析了森林冠层上、下的湍流谱结构和局地各向同性特征。结果表明:在惯性副区内,归一化湍流谱遵循-2/3的指数规律;在冠层上、下,大气湍流并不是各向同性的;而在冠层内则是近似各向同性的;基本说明了在森林冠层内,物质和能量是以小涡形式输送的。从冠层下和冠层上的风速分量和温度谱的峰值频率比较可以得出冠层下的湍涡尺度要相对较小的结论。

The turbulent data was measured at two levels,within and above a forest canopy,in the Changbai Mountains of northeast China in 27th and 28th, May, 2003.By using Eddypro covariance method, this paper dealt with the power spectra and local isotropy of turbulence, and the difference between within and above Changbai Mountain Forest was also analyzed.In the inertial sub range,the normalized turbulent spectral curves had -2/3 slopes.While the shapes of the spectra were in good agreement with the Kansas fiat terrain results ,the atmospheric turbulence was anisotropic above the forest canopy.Due to breaking down of large eddies by the foliage, branches and trunks, the spectral peak frequencies for velocity and temperature were higher within than above the forest canopy.