Nonlinear Dynamics in a Two-Layer Model of Baroclinic Instability and the Effectsof Varying Sidewall Boundary Conditions

摘要

The behavior of two-layer, quasi-geostrophic flow ill a channel, which is subjectto baroclinic instability, is investigated using a high-resolution numerical model. Solutions are obtained for both free-slip sidewalls (which allow tangential velocities but zero stress) and rigid sidewalls (which enforce zero velocity). Results for the slippery model are presented first, and the physics underlying the observed behavior is examined. As the Froude number F is increased, the system exhibits a transition from steady flow to periodic, quasi-periodic, and finally chaotic behavior. As F is increased to about five times the linear critical value, the motion becomes chaotic, and for even larger values of F it moves toward a geostrophic turbulence regime. The route to chaos is determined to be the breakdown of a two-torus.