Hostname: page-component-77c89778f8-7drxs Total loading time: 0 Render date: 2024-07-17T16:55:13.094Z Has data issue: false hasContentIssue false
  • English
  • Français

Instability of wind-forced inertial oscillations

Published online by Cambridge University Press:  26 April 2006

A. M. Treguier  and
P. Klein
A. M. Treguier
Affiliation:
Laboratoire de Physique des Océans, IFREMER, Centre de Brest, BP70, 29280 Piouzané, France
P. Klein
Affiliation:
Laboratoire de Physique des Océans, IFREMER, Centre de Brest, BP70, 29280 Piouzané, France
Get access Rights & Permissions [Opens in a new window]

Abstract

An instability mechanism that can amplify wind-forced inertial oscillations in the upper ocean is investigated. This forced instability happens because of the phase relationship between the mixed-layer depth and the surface current. It allows the inertial oscillations propagating against the wind to extract energy from it and amplify. The key ingredients for the instability to work are (a) a non-zero mean wind stress, (b) a spatial variability of the oscillations in the direction of the wind stress. The amplification is demonstrated using a simple shallow-water model in a few situations: the dispersion of a localized disturbance with steady and time-varying wind forcing, generation of inertial waves at a coast, and spatial variability induced by mesoscale eddies. Estimates of the growth rate are provided for both dissipative and non-dissipative cases.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 275 , 25 September 1994 , pp. 323 - 349
Copyright
© 1994 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arhan, M. 1973 Etude nonlineaire des ondes internes dans un milieu à deux couches fluides en rotation. Rapport CNEXO 17.
Day, C. G. & Webster, F. 1965 Some current measurements in the Sargasso sea. Deep-Sea Res. 12, 805–814.Google Scholar
Crepon, M. 1969 Hydrodynamique marine en regime impulsionnel. Cah. Oceanogr. 21, 333–353.Google Scholar
Csanady, G. T. 1982 Circulation in the Coastal Ocean. Reidel. 279pp.
Gill, A. E. 1982 Atmosphere–Ocean Dynamics Academic. 662pp.
Gill, A. E. 1984 On the behavior of internal waves in the wakes of storms. J. Phys. Oceanogr. 14, 1129–1151.Google Scholar
Grimshaw, R. 1988 Resonant wave interactions in a stratified shear flow. J. Fluid Mech. 190, 357–374.Google Scholar
Kamachi, M. & Grimshaw, R. 1984 Over-reflection of internal waves from the mixed layer. J. Fluid Mech. 141, 179–196.Google Scholar
Klein, P. & Hua, B. L. 1988 Mesoscale heterogeneity of the wind driven mixed layer: influence of a quasi-geostrophic flow. J. Mar. Res. 46, 495–525.Google Scholar
Klein, P. & Treguier, A. M. 1993 Inertial resonance induced by an oceanic jet. J. Phys. Oceanogr. 23, 1897–1915.Google Scholar
Kunze, E. 1985 Near-inertial wave propagation in geostrophic shear. J. Phys. Oceanogr. 15, 544–565.Google Scholar
Lelong, M. P. & Riley, J. J. 1991 Internal wave–vortical mode interactions in strongly stratified–flows. J. Fluid Mech. 232, 1–19.Google Scholar
Millot, C. & Crepon, M. 1981 Inertial oscillations on the continental shelf of the gulf of Lions – Observations and theory. J. Phys. Oceanogr. 11, 639–657.Google Scholar
Niiler, P. P. 1969 On the Ekman divergence in an oceanic jet. J. Geophys. Res. 74, (28), 7048–7052.Google Scholar
Pollard, R. T. 1970 On the generation by winds of inertial waves in the ocean. Deep-Sea Res. 17, 795–812.Google Scholar
Pollard, R. T. & Millard, R. C. 1970 Comparison between observed and simulated wind-generated inertial oscillations. Deep-Sea Res. 17, 813–821.Google Scholar
Price, J. F. 1981 Upper ocean response to a hurricane. J. Phys. Oceanogr. 11, 153–175.Google Scholar
Renouard, D. P., Chabert D'Hières, G. & Zhang, X. 1987 An experimental study of strongly nonlinear waves in a rotating system. J. Fluid Mech. 177, 381–394.Google Scholar
Treguier, A. M. & Hua, B. L. 1987 Oceanic quasi-geostrophic turbulence forced by stochastic wind fluctuations. J. Phys. Oceanogr. 17, 397–411.Google Scholar
Weller, R. A. 1982 The relation of near-inertial motions observed in the mixed layer during the JASIN (1978) experiment to the local wind stress and to the quasi-geostrophic flow field. J. Phys. Oceanogr. 12, 1122–1136.Google Scholar
Weller, R. A., Rudnick, D. L., Eriksen, C. C., Polzin, K. L., Oakey, N. S., Toole, J. W., Schmitt, R. W. & Pollard, R. T. 1991 Forced ocean response during the frontal air–sea interaction experiment. J. Geophys. Res. 96, 8611–8638.Google Scholar