Permalink : http://hdl.handle.net/2115/79113

JaLCDOI : 10.14943/bull.fish.70.1.13

KEYWORDS : Tsugaru Strait;pseudo-fortnightly tide;diurnal tides;passage-flow;form drag

We examine the reason why non-equilibrium response of lunar fortnightly tide, i.e., Mf tide with 13.7-day period, dominates in the Japan/East Sea including the Tsugaru Strait. In the present study, tides combining with passage-flow through the (Tsugaru) Strait are numerically simulated with a two-dimensional form of hydrodynamic model. It has been known that nonlinear interaction of dominant diurnal constituents K1 and O1 results in new oscillation with the same period of Mf tide. Analysis of computed sea level and currents is aimed primarily at describing the enhanced currents and patterns of energy flow in the Strait. Next, the focus of our model study is investigation of mechanisms of pseudo-fortnightly current enhancement where passage-flow interacts with diurnal current variations, resulting in temporal change in the friction due to “form drag”. Thus, we combine the study for form drag of passage-flow with the hydrodynamic interactions of diurnal tidal currents to provide some insight into the locally generated fortnightly tidal forcing within the Strait.