MODELING OF THE INTERNAL WAVE FIELD AND EVALUATION OF THEIR TRANSPORT PROPERTIES ON THE SHELF OF THE KAMCHATKA

AbstractIn the stratified ocean, turbulent mixing is primarily attributed to the breaking of internal waves. As such, internal waves provide a link between large-scale forcing and small-scale mixing. The internal wave field north of the Kerguelen Plateau is characterized using 914 high-resolution hydrographic profiles from novel Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats. Altogether, 46 coherent features are identified in the EM-APEX velocity profiles and interpreted in terms of internal wave kinematics. The large number of internal waves analyzed provides a quantitative framework for characterizing spatial variations in the internal wave field and for resolving generation versus propagation dynamics. Internal waves observed near the Kerguelen Plateau have a mean vertical wavelength of 200 m, a mean horizontal wavelength of 15 km, a mean period of 16 h, and a mean horizontal group velocity of 3 cm s−1. The internal wave characteristics are dependent on regional dynamics, suggesting that different generation mechanisms of internal waves dominate in different dynamical zones. The wave fields in the Subantarctic/Subtropical Front and the Polar Front Zone are influenced by the local small-scale topography and flow strength. The eddy-wave field is influenced by the large-scale flow structure, while the internal wave field in the Subantarctic Zone is controlled by atmospheric forcing. More importantly, the local generation of internal waves not only drives large-scale dissipation in the frontal region but also downstream from the plateau. Some internal waves in the frontal region are advected away from the plateau, contributing to mixing and stratification budgets elsewhere.

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Observations of the Horizontal Interactions between the Internal Wave Field and the Mesoscale Flow

Journal of Physical Oceanography ◽

10.1175/1520-0485(1981)011<1474:oothib>2.0.co;2 ◽

1981 ◽

Vol 11 (11) ◽

pp. 1474-1480 ◽

Cited By ~ 26

Author(s):

Ellen D. Brown ◽

W. Brechner Owens

Keyword(s):

Internal Wave ◽

Wave Field ◽

Internal Wave Field

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Bispectral Analysis of Energy Transfer within the Two-Dimensional Oceanic Internal Wave Field

Journal of Physical Oceanography ◽

10.1175/jpo2816.1 ◽

2005 ◽

Vol 35 (11) ◽

pp. 2104-2109 ◽

Cited By ~ 26

Author(s):

Naoki Furuichi ◽

Toshiyuki Hibiya ◽

Yoshihiro Niwa

Keyword(s):

Internal Wave ◽

Wave Field ◽

Internal Waves ◽

Internal Tide ◽

Energy Cascade ◽

Minor Role ◽

Two Dimensional ◽

Bispectral Analysis ◽

Internal Wave Field ◽

Oceanic Internal Wave

Abstract Bispectral analysis of the numerically reproduced spectral responses of the two-dimensional oceanic internal wave field to the incidence of the low-mode semidiurnal internal tide is performed. At latitudes just equatorward of 30°, the low-mode semidiurnal internal tide dominantly interacts with two high-vertical-wavenumber diurnal (near inertial) internal waves, forming resonant triads of parametric subharmonic instability (PSI) type. As the high-vertical-wavenumber near-inertial energy level is raised by this interaction, the energy cascade to small horizontal and vertical scales is enhanced. Bispectral analysis thus indicates that energy in the low-mode semidiurnal internal tide is not directly transferred to small scales but via the development of high-vertical-wavenumber near-inertial current shear. In contrast, no noticeable energy cascade to high vertical wavenumbers is recognized in the bispectra poleward of ∼30° as well as equatorward of ∼25°. A new finding is that, although PSI is possible equatorward of ∼30°, the efficiency drops sharply as the latitude falls below ∼25°. At all latitudes, another resonant interaction suggestive of induced diffusion is found to occur between the low-mode semidiurnal internal tide and two high-frequency internal waves, although bispectral analysis shows that this interaction plays only a minor role in cascading the low-mode semidiurnal internal tide energy.

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