For example, eastward current extends to 31 N, and 0.2m/s contour reaches 1000m depth. Further, velocity maximum forms below the surface offshore from the velocity core in the model as well as in the observation. Model maximum velocity is about 1.5m/s, which may appear to be larger than the observed one. However, velocity as fast as 1.8m/s was indeed observed by a moored ADCP at 32.5 N, so that the model velocity structure well represents the observation.
Fig 3: Velocity section of a model Kuroshio along the ASUKA line (one-year mean). Inflow transport is 25 Sv
3. Numerical experiments with various inflow transport
In the following experiments we only vary inflow/outflow boundary conditions; wind stress and heat flux forcings are steady here. Figure 4 shows examples of the Kuroshio paths with varying the inflow transport and shear structure. We can see that three types of the Kuroshio path are realized, corresponding to the three different inflow conditions.
In the 25 Sv case (Fig. 4a), Kuroshio flows along Kyushu and Shikoku, then slightly separates after the Kuroshio passes Kii Peninsula. This is a typical feature of the non-large-meander path, and is suggestive of the role of the coastline topography in the path dynamics (e.g. Yamagata and Umatani, 1989). Then, the Kuroshio passes the northern flank of the Hachijo island (see Fig. 1 for the topography) to flow over the Izu Ridge. This corresponds to the typical non-large meander nearshore path according to Kawabe (1985) . The 35 Sv case (Fig. 4b) represents the non-large-meander offshore path. The Kuroshio separates the Japanese coast from the Kii Peninsula, and passes the southern flank of the Hachijo island in this case. The 45 Sv case (Fig. 4c) represents the large meander path. The Kuroshio has a well-defined meander in this case off the south coast of Japan. Note that the Kuroshio returns to the coast westward from the Izu Ridge. It then passes through the ridge on the northern flank of the Hachijo island, flowing out to the Kuroshio extension area.
