Strong internal waves with tidal frequency are observed in some parts of the Japan Sea with vertical displacement of isotherms reaching 50 m that suggests that there most be the areas of these internal waves generation. As it is known, interaction of the barotropic tide with the continental slope could generate baroclinic tidal waves and continental shelf waves. These processes and related mixing in the Japan Sea are analyzed using the Japan Sea numerical ocean circulation model (RIAMOM). Model is grid model with 46 vertical levels (15m-20m resolution in upper 500m), free surface and hydrostatic assumption. Later eliminates from consideration high frequency (~N) internal waves. Horizontal resolution is 1/12 degree for both latitude and longitude, tidal forcing is defined by 16 tidal constituents for the sea level anomaly at open straits boundaries. Seasonally varying inflow and outflow is prescribed in the straits. ECMWF atmospheric sea level pressure, surface wind stress and air temperature are used with 6h time resolution for model forcing. Vertical mixing is estimated by one dimensional turbulent kinetic energy model.
Model results demonstrated that the continental shelf slope in the southern part of the sea on exit from Tsushima strait is a main zone of strong internal tidal wave generation. Being generated these waves propagate eastward along the shelf and decay reaching the eastern shelf slope near the Japan. Vertical velocities related with the internal tidal waves reach ±5*10-3 m/s and vertical displacement is about 50 m that well corresponds to observations in this area. Turbulent mixing generated by the current shear is analyzed as well. Comparison with observed features of internal waves in different parts of Japan Sea is quite realistic. |
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