On the relation between topography and eddy mixing in the Southern Ocean

By applying localized cumulative probability density function (CDF) method and Nakamura (2001)'s mixing efficiency method to output from the Southern Ocean State Estimate, we reveal that the spatial pattern of the enhanced eddy mixing at mid-depths is primarily linked to the merging of multiple jets embedded in the Antarctic Circumpolar Current over topography. We will show through dynamics-based diagnosis and case studies that enhanced eddy mixing over topography is due to locally enhanced baroclinicity and instability within the wake, itself partly due to the convergence of eddies in merging branches of the ACC. We will also show that both the interaction of barotropic and baroclinic eddies and the interaction between stationary waves and transient eddies be important to setting the strength and 3-D structure of eddy mixing associated with topography.