The capture of current meander by coastal geometry with possible application to the Kuroshio Current

Abstract

The problem of the bimodal behavior of the Kuroshio path, south of Japan is discussed by use of the Korteweg-de Vries equation with forcing and dissipation. We show that a localized, large meander of the ocean current is produced by coastal step-like geometry when the upstream current is faster than the long Rossby wave speed. In particular, even if the forcing due to coastal geometry is weak, our dynamical system has a chance to jump from a small meander state to a large meander state because of multiple equilibria. This transition is accomplished by capturing a large, propagating disturbance. These model results are consistent, at least qualitatively, with observations of the Kuroshio.