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Array measurements of atmospheric pressure fluctuations above surface gravity waves

Published online by Cambridge University Press:  20 April 2006

R. L. Snyder ,
F. W. Dobson ,
J. A. Elliott  and
R. B. Long
R. L. Snyder
Affiliation:
Nova University
F. W. Dobson
Affiliation:
Bedford Institute of Oceanography
J. A. Elliott
Affiliation:
Bedford Institute of Oceanography
R. B. Long
Affiliation:
Atlantic Oceanographic and Meteorological Laboratories
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Abstract

A joint experiment to study microscale fluctuations of atmospheric pressure above surface gravity waves was conducted in the Bight of Abaco, Bahamas, during November and December 1974. Field hardware included a three-dimensional array of six wave sensors and seven air-pressure sensors, one of which was mounted on a wave follower. The primary objectives of the study were to resolve differences in previous field measurements by Dobson (1971), Elliott (1972b) and Snyder (1974), and to estimate the vertical profile of wave-induced pressure and the corresponding input of energy and momentum to the wave field.

Analysis of a pre-experiment intercalibration of instruments and of 30 h of field data partially removes the discrepancy between the previous measurements of the wave-induced component of the pressure and gives a consistent picture of the profile of this pressure over a limited range of dimensionless height and wind speed. Over this range the pressure decays approximately exponentially without change of phase; the decay is slightly less steep than predicted by potential theory. The corresponding momentum transfer is positive for wind speeds exceeding the phase speed. Extrapolation of present results to higher frequencies suggests that the total transfer is a significant fraction of the wind stress (0·1 to 1·0, depending on dimensionless fetch).

Analysis of the turbulent component of the atmospheric pressure shows that the ‘intrinsic’ downwind coherence scale is typically an order-of-magnitude greater than the crosswind scale, consistent with a ‘frozen’ turbulence hypothesis. These and earlier data of Priestley (1965) and Elliott (1972c) suggest a horizontally isotropic ‘intrinsic’ turbulent pressure spectrum which decays as k−ν where k is the (horizontal) wave-number and ν is typically −2 to −3; estimates of this spectrum are computed for the present data. The implications of these findings for Phillips’ (1957) theory of wave growth are examined.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 102 , January 1981 , pp. 1 - 59
Copyright
© 1981 Cambridge University Press

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References

Barnett, T. P. & Wilkerson, J. C. 1967 On the generation of wind waves as inferred from air-borne radar measurements of fetch-limited spectra. J. Mar. Res. 25, 292–328.Google Scholar
Bingham, C., Godfrey, M. D. & Tukey, J. W. 1967 Modern techniques of power spectrum estimation. I.E.E.E. Trans. Audio and Electroacoustics AU-15.
Dobson, F. W. 1971 Measurements of atmospheric pressure on wind-generated sea waves. J. Fluid Mech. 48, 91–127.Google Scholar
Dobson, F. W. & Elliott, J. A. 1978 Wave-pressure correlation measurements over growing sea waves with a wave follower and fixed-height pressure sensors. Turbulent Fluxes through the Sea Surface, Wave Dynamics and Prediction (ed. A. Favre & K. Hasselmann). Plenum.
Elliott, J. A. 1972a Instrumentation for measuring static pressure fluctuations within the atmospheric boundary layer. Boundary-Layer Met. 2, 476–495.Google Scholar
Elliott, J. A. 1972b Microscale pressure fluctuations near waves being generated by the wind. J. Fluid Mech. 54, 427–448.Google Scholar
Elliott, J. A. 1972c Microscale pressure fluctuations measured within the lower atmospheric boundary layer. J. Fluid Mech. 53, 351–383.Google Scholar
Harvey, D. R. & Dobson, F. W. 1976 The Bedford Institute Wave Follower. Bedford Inst. of Oceanog. Dartmouth, N.S., Canada. Int. Rep. BI-R-76–13.Google Scholar
Hasselmann, K. 1960 Grrundleichungen der Seegangsvoraussage. Schiffstechnik 7, 191–195.Google Scholar
Hasselmann, K. 1962 On the non-linear energy transfer in a gravity-wave spectrum. 1. General theory. J. Fluid Mech. 12, 481–500.Google Scholar
Hasselmann, K. 1974 On the spectral dissipation of ocean waves due to whitecapping. Boundary-Layer Met. 6, 107–127.Google Scholar
Hasselmann, K., Barnett, T. P., Bouws, E., Carlson, H., Cartwright, D. E., Enke, K., Ewing, J. A., Gienapp, H., Hasselmann, D. E., Krusemann, P., Meerburg, A., Müller, P., Olbers, D. J., Richter, K., Sell W. & Walden, H. 1973 Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP). D.H.I. Zeitschrift A(8), 12.Google Scholar
Long, R. B. 1980 A parametrical model for the vertical structure of the induced atmospherie pressure field above a spectrum of surface gravity waves. J. Fluid Mech. 99, 163–183.Google Scholar
Longuet-Higgins, M. S., Cartwright, D. E. & Smith, N. D. 1963 Observations of the directional spectrum of sea waves using the motions of a floating buoy. In Ocean Wave Spectra, pp. 111–132. Proc. Conf, on Ocean Wave Spectra, Easton, Md, U.S.A., 1901. Prentice-Hall.
Miles, J. W. 1957 On the generation of surface waves by shear flows. J. Fluid Mech. 3, 185–204.Google Scholar
Miles, J. W. 1959 On the generation of surface waves by shear flows. Part 2. J. Fluid Mech. 6, 568–582.Google Scholar
Mitsuta, Y. 1968 Application of sonic anemometer-thermometer to the studies of vertical eddy transport processes in the atmospheric boundary layer. Spec. Contrib., Kyoto Univ. 8, 45–60.Google Scholar
Peep, M. & Flower, R. J. 1969 The Chesapeake Bay Institute Wave Follower. The Johns Hopkins University, Chesapeake Bay Inst., Baltimore, Md, Tech. Rep. 73.Google Scholar
Phillips, O. M. 1957 On the generation of waves by turbulent wind. J. Fluid Mech. 2, 417–445.Google Scholar
Priestley, J. T. 1965 Correlation studies of pressure fluctuations on the ground beneath a turbulent boundary layer. U.S. Nat. Bureau Standards Rep. 8942.Google Scholar
Ross, D. B. & Cardone, V. J. 1978 A comparison of parametric and spectral hurricane wave prediction products. Turbulent Fluxes through the Sea Surface, Wave Dynamics and Prediction (ed. A. Favre K. Hasselmann). Plenum.
Shemdin, O. H. & Hsu, E. Y. 1967 Direct measurement of aerodynamic pressure above a simple progressive gravity wave. J. Fluid Mech. 30, 403–416.Google Scholar
Snyder, R. L. 1974 A field study of wave-induced pressure fluctuations above surface gravity waves. J. Mar. Res. 32, 497–531.Google Scholar
Snyder, R. L. & Cox, C. S. 1966 A field study of the wind generation of ocean waves. J. Mar. Res. 24, 141–178.Google Scholar
Snyder, R. L., Long, R. B., Irish, J., Hunley, D. G. & Pflaum, N. C. 1974 An instrument to measure atmospheric pressure fluctuations above surface gravity waves. J. Mar. Res. 32, 485–496.Google Scholar
Wiener, N. 1949 Extrapolation, Interpolation, and Smoothing of Stationary Time Series. Massachusetts Institute of Technology Press.
Willmarth, W. W. & Wooldridge, C. E. 1962 Measurements of the fluctuating pressure at the wall beneath a thick turbulent boundary layer. J. Fluid Mech. 14, 187–210.Google Scholar