Equilibration of Baroclinic Meanders and Deep Eddies in a Gulf Stream - type Jet over a Sloping Bottom

Spatio-temporal evolution of a small localized meander on a Gulf Stream-type baroclinically unstable jet over a topographic slope is investigated numerically using a threedimensional, primitive equation model. An unperturbed jet is prescribed by a potential vorticity front in the upper thermocline overlaying intermediate layers with weak isentropic potential vorticity gradients and a quiscent bottom layer over a positive (same sense as isopycnal tilt) cross-stream continental slope. A series of numerical experiments with the same initial conditions over a slope and at bottom on the -plane and on the f -plane has been carried out. An initially localized meander evolves into a wave packet and generates deep eddies which provide a positive feedback for the meander growth. We nd that meanders growing over a at bottom are able to pinch o resembling warmand cold-core rings, while in the presence of a weak bottom slope such as 0.002, the maximum amplitudes of meanders and associated deep eddies saturate with no eddy shedding. In the at bottom case, the growth rate is only 10% larger than in the weak slope case. Nevertheless, the bottom slope eÆciently controls nonlinear saturation of meander growth via constraining the development of deep eddies. The topographic slope modi es the evolution of deep eddies and causes the phase displacement of deep eddies in the direction of the upper layer troughs/crests, thus limiting growth of the meanders. Behind the packet peak deep eddies form a nearly zonal circulation which stabilizes the jet in an equlibrated state. The