Constraints on adjacent ocean circulation

This is an investigation of the strong effect of topography on ocean circulation form and stability, the return of shelf-ward baroclinic flow via mixing and in boundary layers, and the diversion of limited depth-integrated flow along the continental slope. The study involves numerical model experiments, initially for a circular basin with uniform shelf. A semi-analytic model is used to investigate modes of an ocean basin with a shelf. Finite-difference and unstructured-grid models will be compared and used to investigate behaviour of flow evolving from an initial meridional density distribution and as a function of flow scale, stratification, friction and mixing. These models will also be used to investigate what global models require to model near-margin circulation, what aspects of shelf representation are important, what reduced models remain sufficient and the utility of the unstructured grid approach.

Later, effects of parameterised mixing in an established ocean model will be studied (1/4° North Atlantic sub-domain of NEMO; Theme 9), and shelf contributions global ocean energy dissipation and overturning.

The figure illustrates baroclinic flow returned in a frictional bottom boundary layer if density differences are overcome by strong lateral mixing.