Observations of internal waves and thermocline splitting near a shelf break of the Sea of Japan (East Sea)

Profiling and mooring measurements have been carried out in the coastal zone of the Peter the Great Bay of the Sea of Japan (East Sea) to study internal wave dynamics and spatial inhomogeneities of thermohaline structure over the shelf. A narrow horizontal seasonal thermocline in the 20-40 m depth range of the open sea was observed to deepen significantly upon approaching the shelf break. This sharp thermocline sometimes thickened over the shelf break with further splitting into two new interfaces. The high-gradient interfaces (sub-layers) underwent further (secondary) splitting several miles shoreward from the shelf break. It is suggested that the deformation of the thermocline is associated with an internal hydraulic jump that originates over the continental slope at a distance 5-15 mile seaward from the shelf break. Internal-wave-induced mixing within the thermocline appears to be a possible mechanism for the generation of a multi-layered thermocline in the coastal zone of the Peter the Great Bay. (C) 2004 Elsevier Ltd. All rights reserved.