Boundary-Layer Meteorology

, Volume 84, Issue 3, pp 383–398

Observation of gravity waves in a boreal forest

  • X. Lee
  • H.H. Neumann
  • G. Hartog
  • R.E. Mickle
  • J.D. Fuentes
  • T.A. Black
  • P.C. Yang
  • P.D. Blanken
Article

DOI: 10.1023/A:1000454030493

Cite this article as:
Lee, X., Neumann, H., Hartog, G. et al. Boundary-Layer Meteorology (1997) 84: 383. doi:10.1023/A:1000454030493

Abstract

In this paper we report the results of the analysis of two 60-min wave events that occurred in a boreal aspen forest during the 1994 BOREAS (Boreal Ecosystems-Atmosphere Study) field experiment. High frequency wind and temperature data were provided by three 3-D sonic anemometer/thermometers and fourteen fine-wire thermocouples positioned within and above the forest. Wave phase speeds, estimated from information revealed by spectral analysis and linear plane wave equations, are 2.2 and 1.3 m s-1 for the two events. The wavelengths are 130 m and 65 m respectively and are much larger than the vertical wave displacements. There is strong evidence from the present analysis and from the literature supporting our postulate that these waves are generated by shear instability. We propose that wind shear near the top of the stand is often large enough to reduce the gradient Richardson number below the critical value of 0.25 and thus is able to trigger the instability. When external conditions are favorable, the instability will grow into waves.

Canopy waves BOREAS Shear instability Phase speed Forest 

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • X. Lee
    • 1
  • H.H. Neumann
    • 2
  • G. Hartog
    • 2
  • R.E. Mickle
    • 2
  • J.D. Fuentes
    • 3
  • T.A. Black
    • 4
  • P.C. Yang
    • 4
  • P.D. Blanken
    • 4
  1. 1.School of Forestry and Environmental StudiesYale University, New HavenConnecticutU.S.A
  2. 2.Atmospheric Environment ServiceEnvironment CanadaTorontoCanada
  3. 3.Department of Environmental ScienceUniversity of VirginiaCharlottevilleU.S.A
  4. 4.Department of Soil ScienceUniversity of British ColumbiaVancouverCanada

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