Energy Transfer within the Small-Scale Oceanic Internal Wave Spectrum

Abstract

Three-dimensional numerical experiments are conducted to examine energy transfer within the small-scale portion of the Garrett?Munk model spectrum of oceanic internal waves. The rate of energy transfer in the experiments is a significant fraction of observed total transfer rate in the interior main thermocline. This transfer may supplement the previous estimate by the eikonal theory. Because nonlinearity is strong in this spectral region, wavenumber-local interactions dominate the energy transfer rather than scale-separated ones. Transfer to higher horizontal wavenumbers is robust, whereas that to higher vertical wavenumbers seems to depend strongly on the spectral shape. Vortical motions seem to be enhancing energy transfer. All of these suggest that further investigation of this spectral region is important and necessary by means of three-dimensional, fully nonlinear analysis.