| The lifetime and spectral transfer of high frequency, low mode-number internal waves of the upper ocean are studied. In addition to the gross exponential Brunt-Vaisala profile, a rectangular bump models the seasonal thermocline in the upper 200m. Internal wave dynamics are governed by a set of nonlinear mode coupling equations derived through a perturbative Hamiltonian description of the fluid equation. Statistical treatment of the mode coupling equations yields two decay/growth rates. The Langevin rate relates to the decay/growth of a single wave train through the ambient internal wave field. Lifetimes are found to range from a few hours to days depending on wave- and mode-numbers as well as profile parameters. The Boltzmann rate determines the evolution of the wave spectrum. A spectrum based on upper ocean data is found to be more in steady-state than the Garrett-Munk spectrum. |
