| Abstract: | Recently a number of authors have analysed the importance of along-isobath density gradients in the vorticity balance governing flows along the continental shelf and slope. The interaction between density gradients and bathymetry has been termed JEBAR (Joint Effect of Baroclinicity and Relief). A recent formulation of these baroclinicity-bathymetry interactions has shown that the pycnobathic term, involving the Jacobian of the bottom density and the depth, can be a source of vorticity. This paper examines the divergence of opinion regarding the importance of pycnobathic forcing.Using a simple expansion of the JEBAR term we show that no JEBAR-type forcing arises when the flow field is geostrophic. We follow this up by allowing small deviations from geostrophy, a quasigeostrophic treatment. We find that when small slope dynamics are employed then a closed problem can be formulated without inclusion of a pycnobathic forcing term. If the dynamics are to apply to regimes characterized by strong bathymetry then the pycnobathic term must enter the formulation. |
