On Universality and Saturation in Ocean Internal Waves
R AND D ASSOCIATES MARINA DEL REY CA
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The apparent regularity in energy distribution among internal-wave space and time scales may be a saturation phenomenon. This paper develops a model of the saturated internal-wave field based on the hypothesis that the saturated quantity is omega squaredN squared, the locally normalized squared vorticity. This quantity, which is a generalized inverse Richardson number for spatially varying flow, is shown in the linearized approximation to be the density of a conserved excitation I the excitation is assumed to be uniformly partitioned among the normal modes in a saturated field. The resulting energy distribution differs from that of Garratt and Munk in that energy is assigned preferentially to the lowest modes. Among the properties derived for this distribution, and subject to verification by ocean measurements, is a universal law, independent of the stratification profile Nz, for coherence spectra of isopycnals in the spatial domain.
- Physical and Dynamic Oceanography