Validation of the Kuroshio Current System in the dual-domain Pacific Ocean Model framework

A fourth-order, fully two-way-coupled dual-domain Pacific Ocean Model (DUPOM) is developed to simulate the regional circulation in Asian Marginal Seas based on the whole North Pacific Ocean simulation framework. The model uses 1/4° and 1/8° horizontal resolutions for the eastern and western Pacific Ocean domains, respectively. The fully two-way-coupled approach shows seamless coupling behavior without any sponge layer. We validate the Kuroshio Current System and the regional circulation in the Asian Marginal Sea, including circulation patterns, volume transport variation and vertical current structure across several cross-sections. A single strong current core exists east of Taiwan and extends to the East China Sea. A cold dome near the northeast of Taiwan is a semi-permanent feature in the model results as observed. South of Japan (e.g. PCM5 line), the Kuroshio shows strong transport along the coast with a countercurrent offshore, reflecting a recirculation gyre. The transient of the three typical paths of the Kuroshio meander is also studied. Our results suggest that the path variation, particularly the Large Meander path, may be triggered by the baroclinic instability associated with westward propagating eddies.