Oceanic internal-wave field: Theory of scale-invariant spectra

Yuri V. Lvov, Kurt L. Polzin, Esteban G. Tabak, Naoto Yokoyama

Research output: Contribution to journalArticle

Abstract

Steady scale-invariant solutions of a kinetic equation describing the statistics of oceanic internal gravity waves based on wave turbulence theory are investigated. It is shown in the nonrotating scale-invariant limit that the collision integral in the kinetic equation diverges for almost all spectral power-law exponents. These divergences come from resonant interactions with the smallest horizontal wavenumbers and/or the largest horizontal wavenumbers with extreme scale separations. A small domain is identified in which the scale-invariant collision integral converges and numerically find a convergent power-law solution. This numerical solution is close to the Garrett-Munk spectrum. Power-law exponents that potentially permit a balance between the infrared and ultraviolet divergences are investigated. The balanced exponents are generalizations of an exact solution of the scale-invariant kinetic equation, the Pelinovsky-Raevsky spectrum. A small but finite Coriolis parameter representing the effects of rotation is introduced into the kinetic equation to determine solutions over the divergent part of the domain using rigorous asymptotic arguments. This gives rise to the induced diffusion regime. The derivation of the kinetic equation is based on an assumption of weak nonlinearity. Dominance of the nonlocal interactions puts the self-consistency of the kinetic equation at risk. However, these weakly nonlinear stationary states are consistent with much of the observational evidence.

Original languageEnglish (US)
Pages (from-to)2605-2623
Number of pages19
JournalJournal of Physical Oceanography
Volume40
Issue number12
DOIs
StatePublished - Dec 1 2010

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Keywords

  • Internal waves
  • Oceanic
  • Spectral analysis
  • Waves

ASJC Scopus subject areas

  • Oceanography

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