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Parameterizing turbulence in low Froude number stratified turbulent flows

Ocean mixing helps drive the global overturning circulation and set the distribution of ocean properties on both small and large scales.  However, the mixing and turbulence that drives the mixing is often unresolved by numerical simulations, and therefore we need to parameterize it.  Tides are one source of energy for this mixing, as stratified flow over rough topography creates internal waves that eventually break.  For gentle topography this process is believed to be dominated by weakly non-linear wave-wave interactions.  However, for abrupt topography substantial turbulence is generated directly at the topography through breaking non-linear lee waves.  Here we demonstrate the phenomenology of these breaking waves, and discuss a simple a-priori method to parameterize the turbulence they produce.