The turnstile mechanism across the Kuroshio current: analysis of dynamics in altimeter velocity fields

Abstract. In this article we explore the utility of dynamical systems tools for visualizing transport in oceanic flows described by data sets measured from satellites. In particular we have found the geometrical skeleton of some transport processes in the Kuroshio region. To this end we have computed the special hyperbolic trajectories, and identified them as distinguished hyperbolic trajectories, that act as organizing centres of the flow. We have computed their stable and unstable manifolds, and they reveal that the turnstile mechanism is at work during several spring months in the year 2003 across the Kuroshio current. We have found that near the hyperbolic trajectories takes place a filamentous transport front-cross the current that mixes waters from both sides.