Transition to Turbulence in Flow over Rough Topography in the Southern Ocean

Geostrophic motions flowing over rough topography in the energetic Antarctic circumpolar current are known to be an important source of mixing, through both locally breaking lee waves and non-propagating vortical motions. We use a combination of theoretical, observational and numerical results to categorize the zoo of processes that occur as eddies and jets impinge on bottom seamounts and ridges in the Southern Ocean. The zoo includes, but is not limited to, propagating lee waves, trapped waves, hydraulics and vortical motions. We further discuss the implications of the differences in the range of processes that emerge for buoyancy budget (through mixing) and the momentum budget (through bottom drag).