SEASONAL CHARACTERISTICS OF LONG-PERIOD CURRENTS FLUCTUATION IN ISHIKARI BAY

Seasonal characteristics of current velocity with the long period were clarified from field data during the longterm in Ishikari Bay. These long period current have a high velocity even at deep water levels outside breaker zones. The fluctuations of current velocity can be estimated by the storm surge formula that assumes wind stress to be the external force and Coriolis force to be the restoring force. The compensation currents were caused by the effect of above things. These currents are dominated near the bottom layer and are larger in winter than in summer. It is seemed that these phenomena were occurred by the seasonal variations of Tsushima warm current.