Internal wave induced boundary layer instabilities: global instability versus isolated events

Over the past few years the role of internal wave induced instabilities has been elucidated by observational, experimental and numerical work. The focus of much of the experimental and numerical work has been on so- called global instabilities that propagate with the wave. In this talk I will contrast numerical simulations of global instabilities in the footprint of internal solitary waves with instability events that occur either due to wave- wave or wave-boundary interactions. These events do not always propagate with the wave. However, they do prove to be vigorous, coherent and common in simulations. They thus considerably expand the size of parameter space (e.g. wave amplitude, geographical extent ) over which vertically trapped internal waves may contribute to sediment resuspension and transport.