Aerodynamic properties of a young spruce stand
2001
Hurtalova, T. (Slovak Academy of Sciences, Bratislava (Slovak Republic). Geophysical Institute ) | Janous, D. | Markova, I.
On the basis of the micrometeorological profile measurements within and above a young spruce stand the aerodynamic properties of this vegetation were analysed. Measurements were carried out at the ecological experimental study site at Bily Kriz, Moravian-Silesian Beskids Mts, the Czech Republic. A young spruce is a part of this study site. This spruce stand in divided into two experimental plots with different densities: Fd (2600 trees per ha) and Fs (2400 trees per ha). For both experimental plots, values of the roughness length z0, zero plane displacement d and drag coefficient CD were determined and its seasonal variations during one growing season were analysed. From the analysis of the vertical wind speed profiles for the Fd-plot it was found that d = 0.76h and for the Fs-plot: d = 0.71h. Empirical relationships between the friction velocity u and wind speed at the top of the stand u (h) were obtained. From this, it followed that the investigated vegetation was in an aerodynamic unsteady state and then the z0 values were dependent on the wind speed. This relation can be described analytically in the form z0/h = 0.244 exp(-0.38 u (h)/u,) for the Fd-plot and z0/h = 0.29 exp(-0.40 u (h)/u,) for the Fs-plot
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