Imbalance on a Baroclinically Unstable Interior Front

In rotating stratified flows of atmospheric and oceanic relevance, the balanced nature of turbulence at scales comparable to the Rossby deformation radius leads to a confinement of energy at the large scales---scales at which eddy and turbulent dissipative processes are ineffective. In the oceanic context, given that ocean circulation is forced mostly at the large scales, a fundamental question regarding the energetics of ocean circulation is as to how the ocean equilibrates. The forward energy cascade of small-scale, three dimensional turbulence is in contrast to the inverse cascade of energy that is characteristic of the above quasi-two-dimensional balanced turbulence. Consequently, the scales and phenomena that span these two asymptotic regimes of turbulence and the interactions of the flow with boundaries are expected to hold the answer to the ocean-equilibration question. In this context, a great amount of research effort in the recent past has focussed on surface and bottom boundary related processes. However, the bulk of the balanced energy resides in the vertical interior and there is the alternative (spatially) more local route to dissipation directly through the interior turbulent cascade (e.g., as pointed out in Molemaker et al., 2005). We study processes and phenomenology associated with such interior turbulent cascades by considering setups that span the range of scales from the deformation radius to scales where imbalance is possible. However, the nature of the turbulent cascades themselves determine as to whether the smaller of the resolved scales can effectively break balance and provide a route that dissipates balanced energy. Are any of the small scales imbalanced---i.e., are they effective in cascading energy down to small scales?