A numerical experiment on the mean wind structure inside canopies of vegetation
✍ Scribed by A.R. Pereira; Roger H. Shaw
- Publisher
- Elsevier Science
- Year
- 1980
- Weight
- 774 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0002-1571
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✦ Synopsis
The form of the wind profile is of concern in many problems involving exchange and diffusion in the canopy formed by vegetation. Yet, we have little quantitative information on the relationship between the wind profile and properties of the foliage because of practical difficulties in modifying existing canopies over a sufficiently large area.
A numerical model based on second-order closure principles was used to calibrate three analytical canopy wind profile models and to test their response to changing foliage density and distribution of vegetation within the canopy. None of the analytical expressions reproduced the layer of very small shear typically present in the lower part of the canopy, but all adequately represented the mean wind in the upper half. When extinction coefficients were related to above-canopy profile parameters, changes due to canopy density and structure were fairly well represented. The only model with an extinction coefficient based on canopy parameters did not accommodate changes caused by restructuring the foliage, and over-reacted to changes in the density of the vegetation. Calibration curves for the three extinction coefficients are presented in graphical form.