Internal wave dynamics on the Australian North west Shelf

[Truncated abstract] Internal waves are a frequently encountered phenomenon throughout the global ocean. They are generated by disturbances to a stratified ocean at frequencies between the inertial and buoyancy frequency. On continental shelf and slope regions, a common generation source is the oscillating barotropic tidal flow over varying topography, which gives rise to the internal tide. Under certain conditions, the internal tide can transform into a set of high-frequency, nonlinear internal waves. In the deep ocean, internal tides are generated at mid-oceanic topographic features. The mechanism of generation of internal waves on the shelf break and at mid-oceanic topographic features is essentially the same. The weak stratification in the deep ocean means that little energy is required here to cause significant mixing (Munk and Wunsch, 2007). Internal tides generated on the shelf break and in the deep ocean are assumed to play a very important role in dissipating tidal energy (Garrett and Kunze, 2007). Assimilation of altimeter data of tides into numerical models (Egbert & Ray 2001) showed that tides lose much more energy in the open ocean compared to coastal waters. This can be ascribed to bottom friction, generally in deep-sea regions with significant topographic features. Internal waves are studied for a variety of reasons. They provide a mechanism for the removal of energy from the barotropic tide, via the internal tide, into high-frequency internal waves, eventually to be dissipated into turbulent motions when the waves break (e.g. Kantha and Tierney, 1997). The strong horizontal currents and vertical shear associated with internal waves may destabilize underwater platforms and drilling operations for oil exploration (Bole et al, 1994).