Mean wind-direction shear through a forest canopy
The equations of motion applying to the wind field in a forest canopy are simplified to a balance between the shearing stress gradient and either the form-drag of the leaves in the upper dense canopy, or the overall horizontal pressure gradient in the more open space beneath. The equations imply that, in descending through the forest, the stress and wind vectors turn through an angle which depends on the forest characteristics and on the stability and the speed of the airflow above the forest. The turning is roughly confirmed by an overall average measured on a very flat site near Thetford, Norfolk, covered by an extensive uniform pine forest.
KeywordsShear Stress Pressure Gradient Open Space Wind Field Forest Canopy
Unable to display preview. Download preview PDF.
- Cionco, R. M.: 1965, ‘A Mathematical Model for Air Flow in a Vegetative Canopy’,J. Appl. Meteorol. 4, 517–522.Google Scholar
- Cionco, R. M., Ohmstede, W. D., and Appleby, J. P.: 1963, ‘Model For Wind Flow in an Idealised Vegetative Canopy’, Met. Res. Notes, No. 5, US Army Electronic Research and Development Activity (Arizona) Huachuca.Google Scholar
- Clarke, R. H.: 1970, ‘Observational Studies in the Atmospheric Boundary Layer’,Quart. J. Roy. Meteorol. Soc. 96, 91–114.Google Scholar
- Hanna, S. R.: 1971, ‘Lateral Turbulence Intensity in a Pine Plantation’, Third Eastern Forest Met. Conf., Syracuse, N.Y.Google Scholar
- Jones, J. I. P.: 1970, ‘A New Recording Wind Vane’,J. Phys., E, J. Sci. Instrum., Ser. 2, London 3, 9–14.Google Scholar
- Kazanski, A. B. and Monin, A. S.: 1961, ‘On the Turbulent Regime, above the Ground Layer of the Atmosphere’,Izv. AN. S.S.S.R., Ser. Geophys. No. 1, 165–168.Google Scholar
- Oliver, H. R.: 1971, ‘Wind Profiles in and above a Forest Canopy’,Quart. J. Roy. Meteorol. Soc. 97, 548–553.Google Scholar
- Ordway, D. E., Ritter, A., Spencer, D. A., and Tan, H. S.: 1961, ‘The Effects of Turbulence and Photosynthesis on CO2 Profiles in the Lower Atmosphere’, Final Report, US Dept. of Agric., Ithaca, N.Y.Google Scholar
- Pasquill, F.: 1961, ‘The Estimation of the Dispersion of Windbourne Material’,Met. Mag. 90, 33–49.Google Scholar