Abstract
Canopy wind profiles can often be represented by an exponential function. The associated attenuation index,a, is found to be proportional to [(Flexibility)(Leaf Area)(Density)]1/3. Leastsquare values of the index have been calculated for wind profiles in about a dozen natural and artificial canopies which included oats, wheat, corn, rice, sunflowers, larch trees, citrus trees, Xmas trees, plastic strips, wooden pegs and bushel baskets. It is found that canopy flow is a function of canopy density, element flexibility, and height and that the behaviour of artificial canopy elements is compatible with that of natural vegetation. The same calculations also show that the attenuation coefficient: (a) is not a universal constant, (b) is however, rather limited in range (∼-0.3 to 3.0), (c) varies with stage of growth, and (d) increases as density and flexibility increase. A compilation ofa-values for several canopies reveals that lowa-values correspond to sparsely arrayed rigid elements while higha-values correspond to densely arrayed and flexible elements. Finally, lowa-values appear to be relatively independent of wind speed, while higha-values tend to increase as wind speeds increase.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allen, L. H., Jr.: 1965, A Comparison of Airflow Pattern within and above Five Different Vegetative Canopies; from 1965 Annual Report of Agricultural Research Service, Ithaca, N.Y.
Allen, L. H., Jr.: 1967,Air Flow and Turbulence Characteristics in a Japanese Larch Plantation; Research Report No. 395, Agricultural Research Service, Ithaca, N.Y. (DDC AD 662720).
Allen, L. H., Jr.: 1968, ‘Turbulence and Wind Speed Spectra within a Japanse Larch Plantation’,J. Appl. Meteor. 7, 73–78.
Brooks, F. A. and Schultz, H. B.: 1958,Observations and Investigations of Nocturnal Density Currents; Climatology and Microclimatology, Proceedings of the Canberra Symposium, UNESCO, Arid Zone.
Brown, K. and Covey, W. C.: 1965, ‘The Energy Budget Evaluation of the Micrometeorological Transfer Processes within a Cornfield’,Agr. Meteorol. 3, 73–96.
Cionco, R. M.: 1965, ‘A Mathematical Model for Airflow in a Vegetative Canopy’,J. Appl. Meteor. 4, 517–522.
Cionco, R. M., Ohmstede, W. D., and Appleby, J. F.: 1963, ‘A Model for Airflow in an Idealized Vegetative Canopy’,Met. Res. Notes No. 5, USAERDAA, Fort Huachuca, Ariz. (DDC AD 422705).
Denmead, O. T.: 1964, ‘Evaporation Sources and Apparent Diffusivities in a Forest Canopy’,J. Appl. Meteorol. 3, 383–389.
Inoue, E.: 1963, ‘On the Turbulent Structure of Airflow within Crop Canopies’,J. Meteor. Soc. Japan., Tokyo, Japan. Sec. II,41, 317–326.
Inoue, E., Lemon, E. R., and Denmead, O. T.: 1964, A Preliminary Investigation into the Airflow within Crop Canopies, Unpublished.
Kutzbach, J. E.: 1961,Investigations of the Modification of Wind Profiles by Artificially Controlled Surface Roughness, Section 7 of Annual Report 1961, Dept. of Meteorology, University of Wisconsin. (DDC AD 273053).
Lemon, E. R., Ordway, D. E., Ritter, A., Spence, D. A., Tan, H. S., Ling, S. D., and Stoller, J.: 1963,The Energy Balance at the Earth's Surface, Part II, USDA Production Report No. 72, Government Printing Office, Washington, D.C. (DDC AD 605527).
Lemon, E. R.: 1964, in F. C. Steward (ed.), ‘Micrometeorology and Physiological Process in the Natural Plant Environment’, Chapter II,Plant Physiology, Vol.IVA, pp. 203–227, Academic Press, New York.
Lemon, E. R.: 1969, ‘Gaseous Exchange in Crop Stands’, Reprinted fromPhysiological Aspects of Crop Yield,Amer. Soc. of Agronomy, Madison, Wisconsin, p. 117–142.
Nakagawa, Y.: 1965, ‘Studies on the Airflow amongst the Stalks in a Paddy Field’,J. Agric. Meteor. 12, 61–63, Tokyo, Japan.
Plate, E. J. and Cermak, J. E.: 1963,Investigations to Develop Wind Tunnel Techniques for Measuring Atmospheric Gaseous Diffusion in Model Vegetative Surface, Fluid Dynamics and Diffusion Laboratory, Colorado State University, Fort Collins, Colorado.
Plate, E. J. and Quraishi, A. A.: 1965, ‘Modeling of Velocity Distributions inside and above Tall Crops’,J. Appl. Meteor. 4, 400–408.
Saito, T.: 1964, ‘On the Wind Profile Within Plant Communities’,Bull. Nat. Inst. Agricultural Sci. 11, 67–73 (Japan), Ser. A.
Tan, H. S. and Ling, S. C.: 1961,A Study of Atmospheric Turbulence and Canopy Flow, TAR-TR 611, Cooperative Research Program: Therm Advanced Research, Inc., U.S. Dept. of Agriculture and Cornell University, Ithaca, New York. Also available in Lemonet al., 1963 (DDC AD 605527).
Uchijima, Z.: 1962, ‘Studies on the Microclimate within Plant Communities. 1. On the Turbulent Transfer Coefficient within Plant Layers’,J. Agr. Meteor. (Tokyo)18, 1–9 (in Japanese with English summaries).
Uchijima, Z. and Wright, J. L.: 1964, ‘An Experimental Study of Airflow in a Cornplant - Airlayer’ (in English with summary in Japanese),Bull. Nat. Inst. of Agr. Sci. (Japan), Ser. A 11, 19–66.
Wright, J. L.: 1965,Evaluating Turbulent Transfer Aero-Dynamically within the Microclimate of a Cornfield, Ph. D. Thesis, Cornell University, Ithaca, New York, 174 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cionco, R.M. A wind-profile index for canopy flow. Boundary-Layer Meteorol 3, 255–263 (1972). https://doi.org/10.1007/BF02033923
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02033923