An Eddy Resolving Numerical Model of the Ventilated Thermocline

Abstract

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 are 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 recirculating/ventilating flow boundaries. Anomalous potential vorticity th...