Numerical study on interaction between eddies and the Kuroshio Current east of Taiwan, China

Abstract

We investigated the interaction between mesoscale eddies and the Kuroshio Current east of Taiwan, China, using a fine-resolution regional general circulation model. Mesoscale eddies are injected into a region east of Taiwan, China, according to the quasi-geostrophic theory of stratified fluids. Modeled eddies propagated westward at the velocity of the first baroclinic mode Rossby wave. When eddies collide with the Kuroshio Current east of Taiwan, China, the spatial structure and volume transport of the Kuroshio Current shows a significant variation. The upper 600 m of the anticyclonic eddy cannot cross the Kuroshio Current to reach the region west of the Kuroshio Current; rather, these waters flow northward along the eastern side of the Kuroshio Current. The upper water carried by the anticyclonic eddies cannot reach the shelf of the East China Sea (ECS). In contrast, the waters in the upper layer of the cyclonic eddy reach the western side of the Kuroshio Current and then flow northward. The dynamic mechanism analysis shows that the interaction between the Kuroshio Current and the cyclonic (anticyclonic) eddy decrease (increase) the horizontal potential vorticity (PV) gradient, or PV barrier, whereby the cyclonic (anticyclonic) eddy can (cannot) cross the Kuroshio Current. This study implies that the continental shelf could potentially be influenced by cyclonic eddies in the open ocean, which can transport heat and material from the upper open ocean across the Kuroshio Current to the shelf waters.