Breaking characteristics of large amplitude internal solitary waves

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Internal solitary waves (ISWs) are ubiquitous features in the Earth's atmosphere and ocean. In particular, they are a commonly occurring feature in the stratified flows of coastal seas, fjords, lakes and the atmospheric boundary layer. They are finite-amplitude waves of permanent form that propagate along density interfaces in stably-stratified fluids. In the ocean they are generated by tidal flows across sub-sea ridges or continental shelves, or when pools of light or heavy water masses relax, having been trapped by the wind along complex coastal topographies. Typically, the waves are highly nonlinear and may attain very large amplitudes. Breaking ISWs can result in significant vertical mixing in the environment in which they propagate. They are an important source of mixing, turbulence and mass and momentum transfer. In physical oceanography, one of the most topical issues of debate is the role of ISWs on the overall mixing of coastal oceans - a process that, in turn, has implications for global ocean circulation, heat transport and climate modelling. In coastal and oceanic regions where offshore petroleum exploration, production and sub-sea storage activities are in progress, both breaking and non-breaking ISWs present significant hazards to the installation and operation of such facilities. In addition, mixing induced by internal waves redistributes nutrients and dissolved gases, thus affecting biological productivity in the oceans. To understand the behaviour of ISWs in these contexts, it is imperative that the evolutionary processes that lead to breaking and the subsequent generation of turbulence are better understood. This proposal will investigate the stability and subsequent wave induced flow of ISWs. A combined theoretical and laboratory parametric modelling study is proposed.