Internal waves in the northern East China Sea

Abstract

The bottom mounted Acoustic Doppler Current Profiler data obtained in the area southwest of Jeju-do in the summer of 2005 and 2006 are used to study internal waves. The observed internal waves generally influenced the whole water column. Manifestation of large-amplitude internal waves was mostly observed during the low tidal phase in 2005, but during a transition phase from high to low tide in 2006. During several internal wave episodes, large-amplitude solitary wave-like features emerged preceding higher frequency internal waves. Shear instability of tidal currents is explored as a possible mechanism for sustaining or regenerating internal waves. The spectral densities of the horizontal velocities approximately followed in the frequency subrange between cpmin and the buoyancy frequency, where is a transition point between the subrange and the steep falloff of energy from the tidal peak at towards higher frequencies.