On the Anisotropy of the Eddy Diffusivity

[摘要] From considerations based on similarity it is found that the ratio of the components of the eddy diffusivity tensor of semiempirical turbulent diffusion theory can be calculated by Kxx/Kzz=(u2)2/(w2)2, Kyy/Kzz=(v2)2/(w2)2 and Kxz/Kzz=-(uw)2/(W2)2 where u, v and w represent the velocity fluctuations in the direction of the mean wind, x, in the lateral, y, and in the vertical direction, z, respectively. The result for Kyy/Kzz is in agreement with that calculated for neutral conditions by Yamamoto and Shimanuki (1964) from data obtained during projects Prairie Grass and Green Glow. The result for Kxz/Kzz has the same order of magnitude as that derivable from turbulent heat flux measurements by Zubkhovskii and Tsvang (1966).

[学科分类] 大气科学