A numerical simulation of wind stress and topographic effects on the kuroshio current path near Taiwan

Abstract

A semispectral primitive equation model is used to study the effects of wind stress and bottom topography on the meandering of a jet over the continental margin. The jet is specified initially as a geostrophic current (similar to the Kuroshio Current) supported by the temperature field. The intrusion of water from the meandering jet over the continental margin is not only dominated by topographic effects but also enhanced by northerly winds. The latter induces an onshore Ekman transport, which causes surface water in the meandering jet to intrude onto the continental margin. Lighter water is then carried downward to the deeper ocean through the hydrostatic and topographic boundary layers. Some subsurface water in the meandering jet also intrudes onto the continental slope and shelf and then rejoins the main stream. Under the influence of southerly wind, surface water in the meandering jet migrates offshore toward the deeper ocean in the Ekman layer, while subsurface water in the meandering jet intrudes onto the continental slope and shelf in the topographic boundary layers. In this case, heavier water is lifted to the sea surface through the topographic boundary and hydrostatic layers. The result suggests that the path of the Kuroshio north of Taiwan is strongly influenced by both the topographic effects and Ekman drift. The intrusions of the meandering Kuroshio surface and subsurface waters are steered and determined by wind directions.