The model hydrography is in good agreement with that observed compared with Fig. 1 in Johnson and Moore (1997). Potential temperature section shows the thermocline centered near the 20℃ isotherm and its shoaling from west to east, poleward shoaling of isotherms (10℃ to 12℃) below the thermocline on either side of the equator (4°to 5°latitudes), and the thermostad between them. It is found that the poleward shoaling is associated with the SCCs comparing temperature with eastward velocity distributions. Salinity sections shows the equatorward convergence of the southern subsurface high salinity water and the northern low salinity water which is a remnant of the North Pacific Intermediate Water. The salinity front in the subsurface layer from 3°N to 5°N is associated with the North SCC, which advects low salinity water from the western boundary area to the east.
The eastward velocity distributions (Fig. 2) show clearly the SCCs with the cores at about 4°N for the NSCC and 5°S to 6°S for the SSCC. The depths of the model SCCs shoal from west to east according to the pycnocline depths. The figure also shows the multiple cores for the SSCC in the central (155°W) and eastern Pacific (110°W), and shows the poleward shift of the poleward side SCC core, which is consistent to the observed result. The velocity distributions are qualitatively consistent with the observation, but there are some differences between model and observed distributions. Gouriou and Toole (1993) shows the observed distribution of the SCCs along 165°E, which has the structures like lobes of the EUC on the either side of the equator. On the other hand, the model SCCs are distinct from the EUC because the cores latitudes are nearly ±4° latitudes slightly north of the observed (±2.5° latitudes).
Isopycnal properties
The model isopycnal properties (Fig. 3) of salinity on 26.5δθ, depths of 26.0δθ and 26.8δθ, and thickness between these two isopycnal surfaces are also quite similar to the observational ones.
Salinity distributions for both model (top of Fig. 3) and observation (top of Fig. 3 in Johnson and Moore, 1997) show low salinity water advection from west to east north of the equator by the NSCC. The salinity minimum shifts slightly to the poleward from 5｡? in the western to 6｡? in the eastern Pacific Ocean. This corresponds to the northward shift of salinity minimum relative to the model NSCC core because the NSCC flows along 4｡? in almost all longitudes. The advection of high salinity water from eastern boundary area is suggested in the eastern Pacific Ocean. The salinity front exists only for north of the equator because the water of the SCC is occupied by the southern subsurface high salinity water (Tsuchiya, 1981).
The distributions of the model isopycnal depths and thickness show similar distribution compared with the observation. The isopycnal 26.0δθis near the base of the pycnocline and the upper boundary of the SCCs. The poleward deepening across the SCCs' cores and eastward deepening are consistent with observational feature. The depth of isopycnal 26.8δθ near the base of the pycnostad is deep in the equator and shoals poleward across the SCCs' cores. The distribution of the model depth of 26.8δθ consistent with the observation qualitatively though it is deeper than the observation by about 50m. The thickness between the isopycnal surfaces is indicative of the pycnostad whose gradient maxima correspond to the SCCs (Johnson and Moore, 1997). The model result shows poleward shift of the maximum gradient from west to east similar to the observed. However, the latitudes of the model SCCs' cores are along nearly the same latitudes zonally as shown below.
