2. Model configuration
We shall briefly describe the configuration of this model in this section; more detailed description may be found somewhere else (e.g. Mitsudera et al 1997). We use a sigma-coordimate, primitive equation ocean model described by Blumberg and Mellor (1987), so-called the Princeton Ocean Model (POM). A curvilinear coordinate grid is used, where the resolution is as high as 1/12 degree near the Japanese coast. Bottom topography is smoothed so that spurious flow should not occur due to the sigma-coordinate of POM. We used Hellerman and Rosenstein (1983) wind stress, and heat flux derived from COADS with weak relaxing to Levitus SST (e.g. Ezer and Mellor,1992) as the surface boundary conditions. As for the lateral boundary condition, radiation condition is used for the barotropic mode, while a sponge layer is used for the baroclinic modes. A turbulent closure model (level 2.5) of Mellor and Yamada (1982) is used to calculate vertical viscosity and diffusivity coefflcients, while Smagorinsky scheme is used to estimate horizontal ones.
Figure 2 shows a sea surface height field from a typical run, including seasonal wind stress and heat flux forcings. Although we shall not discuss this result in detail here (but elsewhere), we would like to point out that the overall features of the Kuroshio system are well represented in this model. For example, we can see: 1) narrow and strong Kuroshio; 2) well-defined recirculation gyres; 3) sharp separation of the Kuroshio from the Boso Peninsula, and distinct Kuroshio extension.
Fig 2: One-year mean Sea Surface height field obtained from the model.
