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Boundary-Layer Meteorology

, Volume 5, Issue 1–2, pp 29–41 | Cite as

Observed generation of an atmospheric gravity wave by shear instability in the mean flow of the planetary boundary layer

  • W. H. Hooke
  • F. F. HallJr.
  • E. E. Gossard
Article

Abstract

Observations of a single boundary-layer event — the generation of an atmospheric gravity wave by an unstable shear flow at Haswell, Colorado on November 12, 1971 — are briefly described and discussed. The observations were made using: (a) an acoustic echo sounder, (b) anemometers mounted at two fixed levels on a 150-m tower, (c) an anemometer and a thermometer mounted on a movable carriage on the tower, and (d) a microbarograph array, including one microbarograph mounted atop the tower. The wave phase velocity (−3.5–4.0 m s−1) was found to equal the wind velocity in the middle of the shear flow, as assumed by other authors. The wave-associated vertical fluxes of momentum and energy measured just above the wave critical layer were estimated to be −5 dyn cm−2 and −800 erg cm−2 s−1, respectively. These are large values. The annual average vertical flux of momentum at temperate and high latitudes is −0.25 dyn cm−2, while the average kinetic energy dissipation rate in a unit column of atmosphere is −5 × 103 erg cm−2 s−1. If the region of wave generation was itself propagating horizontally, its propagation velocity was large compared with the horizontal phase speed of the small-scale waves generated. Wave generation appeared to occur over an area large compared with the size of the microbarograph array (i.e., ≫ 2 km).

Keywords

Shear Zone Pressure Fluctuation Richardson Number Shear Instability Surface Boundary Layer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© D. Reidel Publishing Company 1973

Authors and Affiliations

  • W. H. Hooke
    • 1
    • 2
  • F. F. HallJr.
    • 1
    • 2
  • E. E. Gossard
    • 1
    • 2
  1. 1.Wave Propagation LaboratoryNational Oceanic and Atmospheric AdministrationBoulderUSA
  2. 2.Environmental Research LaboratoriesNational Oceanic and Atmospheric AdministrationBoulderUSA

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