Features of the nonlinear internal wave spectrum in the coastal zone

This paper studies two examples of internal wave band temperature fluctuation spectra from moored instruments on the central Mexican Pacific Shelf and the western shelf of the Japan/East Sea. It is observed that for band f ≪ ω ≪ N, where N is the buoyancy frequency and f is the inertial frequency, the spectral falloff rate with frequency ω tends to ω−3. These features of spectra are simulated by the model spectrum of nonlinear internal waves in the shallow sea. It is shown that nonlinear internal waves with frequencies f ≪ ω ≪ N are governed by the modified simple wave equation. This equation underlie of the model spectrum of nonlinear internal waves on the shelf. The model spectrum shows ω−3 falloff rate with frequency in contrast with model spectrum proposed with Garrett and Munk, which shows ω−2 falloff rate.