Chaos in Thèsliced Cone' Model of Wind-driven Ocean Circulation

This paper presents a numerical exploration of the behavior of thèsliced cone' laboratory apparatus, a simple model of wind-driven ocean circulation in a basin entirely bounded by continental shelves. The asymptotic (large time) variability of the ow is studied as a function of forcing strength using the techniques of dynamical systems theory. This approach sheds light on the transitions which ultimately transform a steady ow under weak forcing (small Rossby number Ro) into a chaotic ow at large Ro. Time dependence initially arises via a Hopf bifurcation at a critical Rossby number, taking the ow from a steady to a periodic state; this periodic ow becomes quasiperiodic following a second Hopf bifurcation at larger Ro. The transitions leading to chaos are more complex, and involve the appearance of a second branch of solutions and intermittent transitions between the two branches.