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On the diffusion of momentum and mass by internal gravity waves

Published online by Cambridge University Press:  11 April 2006

Peter Mtfller
Affiliation:
Institut für Geophysik, Universität Hamburg, 2 Hamburg 13, Bundestrasse 55, Germany

Abstract

The interaction between short internal gravity waves and a larger-scale mean flow in the ocean is analysed in the Wkbj approximation. The wave field determines the radiation-stress term in the momentum equation of the mean flow and a similar term in the buoyancy equation. The mean flow affects the propagation characteristics of the wave field. This cross-coupling is treated as a small perturbation. When relaxation effects within the wave field are considered, the mean flow induces a modulation of the wave field which is a linear functional of the spatial gradients of the mean current velocity. The effect that this modulation itself has on the mean flow can be reduced to the addition of diffusion terms to the equations for the mass and momentum balance of the mean flow. However, there is no vertical diffusion of mass and other passive properties. The diffusion coefficients depend on the frequency spectrum and the relaxation time of the internal-wave field and can be evaluated analytically. The vertical viscosity coefficient is found to be vv [ape ] 4 x 103cm2/s and exceeds values typically used in models of the general circulation by at least two orders of magnitude.

Type
Research Article
Copyright
© 1976 Cambridge University Press

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References

Barrett, J. R. 1971 Available potential energy of Gulf Stream rings. Deep-sea Res. 18, 12211231.Google Scholar
Bell, T. H. 1974 Topographically generated internal waves in the open ocean. J. Geophys. Res. 80, 320327.Google Scholar
Breteerton, F. P. 1966 The propagation of groups of internal gravity waves in a shear flow. Quart. J. Roy. Met. Soc. 92, 466480.Google Scholar
Bretherton, F. P. 1968 Propagation in slowly varying waveguides. Proc. Roy. Soc. A 302, 555576.Google Scholar
Bretherton, F. P. 1969 On the mean motion induced by internal gravity waves. J. Fluid Mech. 36, 785803.Google Scholar
Bretherton, F. P. 1970 Linearized theory of wave propagation. Lectures in Appl. Math. 13, 61102.Google Scholar
Bretherton, F. P. & Garrett, C. J. R. 1968 Wavetrains in inhomogeneous moving media. Proc. Roy. Soc. A 302, 529554.Google Scholar
Bretherton, F. P. & Karweit, M. 1974 Midocean mesoscale modelling. Proc. Symp. Numerical Models of Ocean Circulation. Durham: U.S. Nat. Acad. Sci.Google Scholar
Cheney, R. & Richardson, P. L. 1976 Observed decay of a cyclonic Gult Stream ring. Deep-sea Res. 23, 143156.Google Scholar
Fomin, L. M. 1972 On the vertical structure of mesoscale currents in the ocean. Unpublished manuscript.Google Scholar
Frankiqnoul, C. J. 1974 Observed anisotropy of spectral characteristics of internal waves induced by low frequency currents. J. Phys. Ocean. 4, 625634.Google Scholar
Frankignoul, C. J. 1976 Observed interaction between oceanic internal waves and mesoscale eddies. Deep-sea Res. (in Press).Google Scholar
Fuglister, F. C. 1971 Cyclonic rings formed by the Gulf Stream 1965–66. Studies in Physical Oceanography. Gordon & Breach.Google Scholar
Garrett, C. J. R. & Munk, W. 1972 Space-time scales of internal waves. Geophys. Fluid Dyn. 2, 225264.Google Scholar
Garrett, C. J. R. & Munk, W. 1975 Space-time scales of internal waves: a progress report. J. Geophys. Res. 80, 291298.Google Scholar
Gill, A. E., Green, J. S. A. & Simmons, S. 1974 Energy partition in the large-scale ocean circulation and the production of midocean eddies. Deep-sea Res. 21, 499528.Google Scholar
Hasselmann, K. 1968 Weak interaction theory of ocean waves. Basic Developments in Pluid Dyn. 2, 117182.Google Scholar
Hasselmann, K. 1971 On the mass and momentum transfer between short gravity waves and larger-scale motions. J. Fluid Mech. 50, 189205.Google Scholar
Hendry, R. 1975 Ph.D. thesis, MIT and Woods Hole Oceanographic Institution.Google Scholar
Jones, W. L. 1967 Propagation of internal gravity waves in fluids with shear flow and rotation. J. Fluid Mech. 63, 801825.Google Scholar
Katz, E. J. 1975 Tow spectra from Mode. J. Geophys. Res. 80, 11631167.Google Scholar
Kitano, K. 1975 Some properties of the warm eddies generated in the confluence zone of the Kuroshio and Oyashio currents. J. Phys. Ocean. 5, 245252.Google Scholar
Landau, L. D. & Lifshitz, E. M. 1962 Course of Theoretical Physics, vol. 3, chap. 6, § 38. Pergamon.Google Scholar
Mcintyre, M. E. 1973 Mean motions and impulse of a guided internal gravity wave packet. J. Pluid Mech. 60, 801811.Google Scholar
Molinari, R. L. 1970 Cyclonic ring spin down in the North Atlantic: Ph.D. thesis, Texas A & M University.Google Scholar
Müller, P. 1974 On the interaction between short internal waves and larger scale motions in the ocean. Ph.D. thesis, University of Hamburg. Hamburger Geophysika-lische Einzelschriften, no. 23.Google Scholar
Müller, P. & Olbers, D. J. 1975 On the dynamics of internal waves in the deep ocean. J. Geophys. Rea. 80, 38483860.Google Scholar
Muller, P., Olbers, D. J. & Willebrand, D. J. 1975 Spectral interpretation of data from Iwex (abstract). Iapso Sci. Program, Grenoble.Google Scholar
Mysak, L. A. & HOW, M. S. 1976 A kinetic theory for internal waves in a randomly stratified ocean. Dyn. Atmos. Oceans, 1, 331.Google Scholar
Olbers, D. J. 1974 Decay of internal wave beams by resonant interactions. Status Rep. on 1 WEX.Google Scholar
Olbers, D. J. 1976 Non-linear energy transfer and the energy balance of the internal wave field in the deep ocean. J. Fluid Mech. 74, 375399.Google Scholar
Parker, C. E. 1971 Gulf Stream rings in the Sargasso Sea. Deep-sea Res. 18, 981993.Google Scholar
Rhines, P. B. 1973 Observations of the energy-containing oceanic eddies, and theoretical models of waves and turbulence. Boundary-Layer Met. 4, 345360.Google Scholar
Rhines, P. B. 1975 Waves and turbulence on a beta-plane. J. Fluid Mech. 69, 417443.Google Scholar
Robinson, A. R. 1975 The variability of ocean currents. Rev. Geophys. Space Phys. 13, 598601.Google Scholar
Roeteer, W., Münnich, K. O. & Östlund, H. G. 1970 Tritium profile at the North Pacific (1969) Geosecs Intercalibration station. J. Geophys. Res. 75, 76727675.Google Scholar
Rooth, C. G. & Östlund, H. G. 1972 Penetration of tritium into the Atlantic thermo-cline. Deep-sea Res. 19, 481492.Google Scholar
Sanford, T. B. 1975 Observations of the vertical structure of internal waves. J. Geophys. Res. 80, 38613871.Google Scholar
Saunders, P. M. 1971 Anticyclonic eddies formed from shoreward meanders of the Gulf Stream. Deep-sea Res. 18, 12071219.Google Scholar
Thorpe, S. A. 1973 Turbulence in stable stratified fluids: a review of laboratory experiments. Boundary-Layer Met. 5, 95119.Google Scholar
Whitham, G. B. 1965 A general approach to linear and non-linear dispersive waves using a Lagrangian, J. Fluid Mech. 22, 273283.Google Scholar
Wunsch, C. 1975 Internal tides in the ocean. Rev. Geophys. Space Phys. 13, 167182.Google Scholar