Dynamics of Gap-leaping Western Boundary Currents with Throughflow Forcing

The dynamics of gap-leaping western boundary currents (e.g. the Kuroshio intrusion, the Loop Current) are explored through rotating table experiments. Simplified experimental and numerical models of gap-leaping systems are known to exhibit two dominant states (leaping or penetrating the gap) as inertia competes with vorticity. These systems admit multiple states with hysteresis as the strength of the current is varied. To advance towards more realistic oceanographic scenarios, recent studies have explored the effects of islands, mesoscale eddies, and variable baroclinic deformation radii on the dynamical system. Here, the effect of throughflow forcing is considered in lab experiments using particle tracking velocimetry (PTV). Mean transport in or out of the gap is found to significantly shift the hysteresis range as well as change its width. Because of these transformations, changes in throughflow can induce transitions in the gap-leaping system when near a critical state (leaping to penetrating/ penetrating to leaping). Results from the study are interpreted within a nonlinear dynamical framework and various properties of the system are explored.