Numerical experiments of nonlinear energy transfer within the oceanic internal wave spectrum

From the fact that the Garrett‐Munk‐like (GM‐like) internal wave spectrum is maintained even in regions of weak local energy sources, it is believed that energy is continuously supplied to the local wave spectrum by internal waves propagating from source regions where they are generated by wind stress fluctuations or tide‐topography interactions. In order to examine how the energy thus supplied by propagating internal waves cascades through the local wave spectrum down to small dissipation scales, we carry out three sets of numerical experiments where the quasi‐equilibrium internal wave spectrum obtained by Hibiya et al. [1996] is perturbed with forcing applied to different parts of the low‐frequency low‐wavenumber portion. The evolution of the internal wave spectrum is examined over eight inertial periods after the forcing is applied. First, in experiment I the forcing is applied to the low‐vertical‐wavenumber inertial‐frequency (ω=f) portion of the spectrum. In this case, no significant increase or decrease of spectral intensity can be seen within the two‐dimensional wavenumber spectrum. Next, in experiment II the forcing is applied at low‐vertical wavenumbers in the frequency range of 2f