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).
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References
Beran, D. W., Little, C. G., and Willmarth, B. C.: 1971, ‘Acoustic Doppler Measurements of Vertical Velocities in the Atmosphere’,Nature 230, 160–162.
Brunt, D.: 1939,Physical and Dynamical Meteorology, Cambridge University Press, Cambridge.
Chimonas, G.: 1972, ‘The Stability of a Coupled Wave-Turbulence System in a Parallel Shear Flow’,Boundary-Layer Meteorol. 2, 444–452.
Drazin, P. G.: 1958, ‘The Stability of a Shear Layer in an Unbounded Heterogeneous Inviscid Fluid’,J. Fluid Mech. 4, 214–224.
Eckart, C.: 1960,Hydrodynamics of Oceans and Atmospheres, Pergamon Press, London.
Emmanuel, C. B.: 1973, ‘Richardson Number Profiles Through Shear Instability Wave Regions Observed in the Lower Planetary Boundary Layer’,Boundary-Layer Meteorol. 5, 19–27.
Emmanuel, C. B., Bean, B. R., McAllister, L. G., and Pollard, J. R.: 1972, ‘Observations of Helmholtz Waves in the Lower Atmosphere with an Acoustic Sounder’,J. Atmospheric Sci. 29, 886–892.
Gossard, E. E. and Munk, W. H.: 1954, ‘On Gravity Waves in the Atmosphere’,J. Meteorol. 11, 259–269.
Gossard, E. E., Richter, J. H., and Atlas, D.: 1970, ‘Internal Waves in the Atmosphere from High-Resolution Radar Measurements’,J. Geophys. Res. 75, 3523–3536.
Gossard, E. E., Jensen, D. R., and Richter, J. H.: 1971, ‘An Analytical Study of Tropospheric Structure as Seen by High-Resolution Radar’,J. Atmospheric Sci. 28, 794–807.
Hines, C. O.: 1970, ‘Comments on Paper by E. E. Gossard and J. H. Richter, and D. Atlas, ‘Internal Waves in the Atmosphere from High Resolution Radar Measurements’,J. Geophys. Res. 75, 5956–5959.
Hines, C. O. and Reddy, C. A.: 1970, ‘On the Propagation of Atmospheric Gravity Waves through Regions of Wind Shear’,J. Geophys. Res. 72, 1015–1034.
McAllister, L. G., Pollard, J. R., Mahoney, A. R., and Shaw, P. J. R.: 1969, ‘Acoustic Sounding — A New Approach to the Study of Atmospheric Structure’,Proc. IEEE 57, 579–587.
Palmén, E. and Newton, C. W.: 1969,Atmospheric Circulation Systems, Academic Press, New York.
Phillips, O. M.: 1966,The Dynamics of the Upper Ocean, Cambridge University Press.
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Hooke, W.H., Hall, F.F. & Gossard, E.E. Observed generation of an atmospheric gravity wave by shear instability in the mean flow of the planetary boundary layer. Boundary-Layer Meteorol 5, 29–41 (1973). https://doi.org/10.1007/BF02188309
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DOI: https://doi.org/10.1007/BF02188309