Internal Tidal Fronts in the Coastal Zone of the Japan Sea

V. V. Novotryasov, E. P. Pavlova, and M. S. Permyakov

Presented are the results of the studies of internal tidal fronts in the coastal zone of the Japan Sea carried out in October 2012 using the anchored buoy stations which were installed on the route sit- uated along the normal to the isobaths of the coastal zone. The analysis demonstrated that there are fast-moving internal tidal fronts in the field of coastal water temperature. These fronts represent the lift- ing of the thermocline limited in space and reaching 1/3 of the depth of the coastal zone with the steep leading edge and with the nonstationary wave zone adjoining it. This zone is filled with high-frequency pulsations having the periods of 3–5 minutes and amplitudes up to 10 m. It is revealed that internal tidal fronts propagate with the velocity of the first mode of the internal wave and with the frequency of the tidal harmonic M2. They are the highly nonlinear formations (the parameter of nonlinearity is ~0.3) filled with high-frequency (the frequency ~ 20 cycle/hour) amplitude-modulated disturbances with the steepness of the wave front of ~8 cm/s; their length is ~1 km.