A numerical study of motion and spindown characteristics of an isolated cyclonic oceanic vortex

Abstract

The motion and spindown characteristics of oceanic mesoscale vortices have been examined through the use of a finite difference equivalent barotropic numerical model. Variable parameters in the study include vortex size, nonlinear strength and initial profile shape. Both Gaussian and a non-Gaussian fit to an observed current ring are used as initial profiles. A time dependent behavior is observed in which the vortex approaches a quasi-equilibrium velocity. Results shows vortex velocity to be a function of all three variables. Energy transfer processes are found to be significantly influenced by vortex initial profile shape. Nonlinearity is shown to stabilize the ring against dispersive effects. Vortex decay as a function of size and strength is parameterized in terms of lateral spreading of energy. Barotropic instability in several strongly nonlinear non-Gaussian experiments results in a rapid breakdown of the initial vortex.