These figures indicates that the model Kuroshio tends to take the large meander path when the inflow transport is large. This tendency is similar to that in various numerical experiments such as Chao (1983), Yoon and Yasuda (1987), and Akitomo et al (1994).
What causes this difference in this model? From the figures in Fig. 4, we notice that the recirculation gyre in the 45Sv case is remarkably intensified compared to that of the 25Sv case. We therefore examined the potential vorticity field in the recirculation gyre. Figure 5 shows scatter plots of the depth-integrated potential vorticity in terms of the transport function in the Shikoku basin for the non-large meander case and the large meander case. Here, the transport function ψ along a section s and the depth-integrated potential vorticity Q are defined as
Ψ = ∫sHV･nds, Q = (f + ▽H-1▽Ψ) / H,
where V, f, H, and n are the depth integrated velocity vector, the Coriolis parameter, total depth, and the unit vector normal to the the section 5, respectively.
