Boundary-Layer Meteorology

, Volume 45, Issue 4, pp 391–409

Influence of foliar density and thermal stability on profiles of Reynolds stress and turbulence intensity in a deciduous forest

  • R. H. Shaw
  • G. Den Hartog
  • H. H. Neumann


Observations were made of turbulence in an extensive deciduous forest on level terrain using a vertical array of seven three-dimensional sonic anemometer/thermometers within and above the canopy. Data were collected through the period of leaf fall and over a range of thermal stabilities. A bulk canopy drag coefficient was nearly independent of the density of the forest but decreased greatly with the onset of nocturnal stability. The depth of penetration of momentum into the forest increased with leaf fall but, again, was greatly curtailed by stable conditions. Turbulent velocities decreased with increasing depth in the forest but relative turbulence intensities increased to mid-canopy levels. Leaf density influenced turbulence levels but not as strongly as did thermal stability. Thermal effects were adequately described by the single parameter h/L, where h is the canopy height and L is the Monin-Obukhov length. The longitudinal and vertical velocity correlation coefficient was larger in magnitude than expected in the upper layers of the forest but decreased to a small value in the lowest layers where the Reynolds stress was small. The ratio Σw/u*, where u* is the local friction velocity, reflected changes in the uw correlation, becoming smaller than usual in the upper canopy layers. It is believed that these effects result from the intermittent, spatially coherent structures that are responsible for a large fraction of the momentum flux to the forest.


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  1. Allen, L. H., Jr.: 1968, ‘Turbulence and Wind Speed Spectra within a Japanese Larch Plantation’, J. Appl. Meteorol. 7, 73–78.Google Scholar
  2. Amiro, B. D. and Davis, P. A.: 1988, ‘Statistics of Atmospheric Turbulence within a Natural Black Spruce Forest Canopy’, Boundary-Layer Meteorol. 44, 267–283.Google Scholar
  3. Baldocchi, D. D. and Hutchison, B. A.: 1987, ‘Turbulence in an Almond Orchard: Vertical Variations in Turbulence Statistics’, Boundary-Layer Meteorol. 40, 127–146.Google Scholar
  4. Baldocchi, D. D. and Meyers, T. P.: 1988, ‘Turbulence Structure in a Deciduous Forest’, Boundary-Layer Meteorol. 43, 345–364.Google Scholar
  5. Businger, J. A., Wyngaard, J. C., Izumi, Y., and Bradley, E. F.: 1971, ‘Flux-Profile Relationships in the Atmospheric Surface Layer’, J. Atmos. Sci. 28, 181–189.Google Scholar
  6. Dolman, A. J.: 1986, ‘Estimates of Roughness Length and Zero Plane Displacement for a Foliated and Non-Foliated Oak Canopy’, Agric. Forest Meteorol. 36, 241–248.Google Scholar
  7. Dyer, A. J. and Hicks, B. B.: 1970, ‘Flux-Gradient Relationships in the Constant Flux Layer’, Quart. J. Roy. Meteorol. Soc. 96, 715–721.Google Scholar
  8. Finnigan, J. J.: 1979, ‘Turbulence in Waving Wheat. II. Structure of Momentum Transfer’, Boundary-Layer Meteorol. 16, 213–236.Google Scholar
  9. Gao, W., Shaw, R. H., and Paw, U. K. T.: 1988, ‘Structure of Turbulence within and above a Forest’, Proceedings of the Eighth Symposium on Turbulence and Diffusion of the Amer. Meteorol. Soc., San Diego, April 26–29.Google Scholar
  10. Haugen, D. A., Kaimal, J. C., and Bradley, E. F.: 1979, ‘An Experimental Study of Reynolds Stress and Heat Flux in the Atmospheric Surface Layer’, Quart. J. Roy. Meteorol. Soc. 97, 168–180.Google Scholar
  11. Hosker, R. P., Jr., Nappo, C. P., Jr., and Hanna, S. R.: 1974, ‘Diurnal Variation of the Thermal Structure in a Pine Plantation’, Agric. Meteorol. 13, 259–265.Google Scholar
  12. Lesnik, G. E.: 1974, ‘Results of Measurement of the Turbulent Energy Balance Components in a Layer of Vegetation’, Atmos. Oceanic Phys. 10, 400–401.Google Scholar
  13. McBean, G. A.: 1968, ‘An Investigation of Turbulence within the Forest’, J. Appl. Meteorol. 7, 410–416.Google Scholar
  14. Neumann, H. H., den Hartog, G., and Shaw, R. H.: 1988, ‘Leaf Area Measurements during Autumn Leaf Fall for a Deciduous Forest Based on Hemispheric Photographs and Leaf-Litter Collection’, Agric. Forest Meteorol., (in press).Google Scholar
  15. Panofsky, H. A., Tennekes, H., Lenschow, D. H., and Wyngaard, J. C.: 1977, ‘The Characteristics of Turbulent Velocity Components in the Surface Layer under Convective Conditions’, Boundary-Layer Meteorol. 11, 355–361.Google Scholar
  16. Pinker, R. T. and Holland, J. Z.: 1988, ‘Turbulence Structure of a Tropical Forest’, Boundary-Layer Meteorol. 43, 43–63.Google Scholar
  17. Shaw, R. H., Silversides, R. H., and Thurtell, G. W.: 1974, ‘Some Observations of Turbulence and Turbulent Transport within and above Plant Canopies’, Boundary-Layer Meteorol. 5, 429–449.Google Scholar
  18. Shaw, R. H., Tavangar, J., and Ward, D. P.: 1983, ‘Structure of the Reynolds Stress in a Canopy Layer’, J. Clim. Appl. Meteorol. 22, 1922–1931.Google Scholar

Copyright information

© Kluwer Academic Publishers 1988

Authors and Affiliations

  • R. H. Shaw
    • 1
  • G. Den Hartog
    • 2
  • H. H. Neumann
    • 2
  1. 1.Department of Land, Air and Water ResourcesUniversity of CaliforniaDavisUSA
  2. 2.Atmospheric Environment ServiceDownsviewCanada

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