Abstract
A warm water region has always been seen south of the Kuroshio, south of Honshu. Focusing our attention on the warm water region, we analysed oceanographic data since 1938. The results suggest that there may be two dominant circulation patterns superposed upon each other, in the western North Pacific, one of which may be a circulation intensely affected by zonal wind stress and elongated in the east-west direction along the Kuroshio, and the other may be constrained by bottom topography and elongated in the north-south direction, when zonal wind stress weakens in the northern hemisphere. In the latter, the oceanic area south of Tokaido becomes a dynamical trough and a cold water region is likely to occur. The warm water region south of Shikoku becomes dominant, too.
