Eikonal calculations of short‐wavelength internal‐wave spectra

Following Henyey and Pomphrey (1983), we investigate the spectrum of small‐scale internal waves using the eikonal method. We send test‐wave packets through background internal‐wave shear fields, varying the initial distributions and the background spectra. We find that the test‐wave distributions evolve to Garrett‐Munk wave number spectra for all the cases investigated. We find that the test waves evolve toward higher frequencies, in contrast to a simple induced diffusion model, and consistent with a picture of low‐frequency internal‐wave sources.