The opening of south boundary makes the simulated temperature and salinity of the North Pacific Intermediate Water(NPIW) lower and the low salinity water tongue deeper to extend southward, so the simulated results with open boundary conditions are closer to the observations. 南边界打开后使得模拟的北太平洋中层水温度和盐度更低,低盐水舌加深和向南延伸加强,更加接近观测值。