Cox, M. D., 1985: An eddy resolving numerical model of the ventilated thermocline. Journal of Physical Oceanography, 15 (10), 1312-1324.
Abstract: A three-dimensional, primitive equation numerical model is used to study
the effects of mesoscale eddies within the subtropical thermocline. Solutions
are obtained for an ocean bounded by idealized topography and driven by
simple wind and buoyancy forcing at the surface. Results using an eddy-resolving,
fine grid are compared to those using a noneddy-resolving, coarser grid.
Relatively little difference is realized in the basic, mean flow patterns
of the two solutions. However, more significant differences are seen in
the distributions of a passive tracer and the potential vorticity. Mixing
by eddies in the westward flowing sector of the subtropical gyre is quite
effective in homogenizing these quantities on isopycnals.
Whereas previous theory has predicted homogenization of potential vorticity
on long time scales within recirculating gyres, the present model demonstrates
homogenization on a much shorter time scale, across recirculationg/ventilating
flow boundaries. Anomalous potential vorticity that is advected into the
thermocline from isopycnal outcrops by ventilated flow causes changes in
sign of the meridional gradient of local potential vorticity, which in turn
gives rise to baroclinic instability. The resulting eddies serve to homogenize
the anomalous potential vorticity with its environment.
Net poleward heat transport is quite similar in the two solutions. Equatorward
heat transport by time variant flow due to eddies is compensated by an additional
contribution of the eddies to the mean meridional circulation, producing
a net heat transport nearly the same as that of the noneddy-resolving solution.