Tidally generated near-resonant internal wave triads at a shelf break

Numerical simulations of internal wave generation by tidal flow over a shelf break using a linear background stratification show the presence of near‐resonant internal wave triads with spatially modulated amplitudes propagating away from the shelf break. The near‐resonant triad is comprised of mode‐one and ‐three waves of tidal frequency, which are directly forced by the tide‐topography interaction, and a second harmonic, mode‐two wave generated by the nonlinear interaction of these waves. A theory for these near‐resonant triads is presented and compared with the numerical simulations.