Tidal front at Osaka Bay, Japan, in winter

The detailed structure of an oceanic front at Osaka Bay, Japan was observed in January 1992. The front separates the stratified nearshore region from the well-mixed region of the central part of the bay. The front runs in the domain where the value of log(h/U3) (where h is the water depth in meters and U the amplitude of the M2 tidal current in m s−1) ranges from 3.0 to 3.5, showing that tidal stirring plays an important role in its formation. We may consider this front as a tidal front in winter, because the large fresh water inflow generates the density stratification in spite of the strong sea surface cooling. The difference of positions of the tidal front at Osaka Bay between winter and summer is also discussed.