Generation of Internal Waves in the Southern Ocean.

Recent estimates from LADCP observations and inverse models show an enhanced turbulent mixing in the Southern Ocean associated with internal wave breaking. This mixing is typically concentrated in the bottom 1- 2 km. Enhanced abyssal mixing has been recently linked to internal tides. In this study we suggest that enhanced mixing in the Southern Ocean regions can be sustained by lee waves generated by balanced geostrophic motions flowing over bottom topography. The process of lee wave generation, radiation and breaking is examined using a two-dimensional numerical simulation. The model is run for mean flows and topographic data representative of the Drake Passage regions. The numerical simulations reproduce the magnitude and distribution of dissipation measured in the region. We comment on the implications of these results for the overturning circulation of the Southern Ocean.