A geostrophic adjustment model of shelfward intrusion of oceanic upper water across a depth discontinuity: implication to the Kuroshio region

The dynamics of gravity-forced intrusion of the oceanic upper water onto the shelf across a depth discontinuity is considered by using a simple geostrophic adjustment model with application to the Kuroshio region bordering the East China Sea Shelf in mind. The external parameters affecting the intrusion of the oceanic upper water are found to be the difference in surface elevation between the shelf and the oceanic regions, the relative density difference between two water masses and the bottom depth of the shelf. The sea level difference moves the frontal system shelfward through barotropic effect whereas the density difference increases the frontal width through baroclinic effect. Both effects favorably act upon the intrusion of the oceanic upper water. The barotropic and baroclinic effects are pronounced relatively more, respectively, for the larger and smaller depth changes across the slope. For the oceanic upper water initially in motion in the same direction as that due to the adjustment and conserving the potential vorticity of the resting state, the intrusion is greatly hindered.