The VENUS observatory measures the tide and large surface waves with our pressure sensors, but internal waves also exist and can sometimes been seen in the inverted echo-sounder data. Here is a one hour record of the 200 kHz ZAP inverted echo-sounder data from the Delta Dynamics Laboratory (DDL) on 11 January 2012 (20:00 UTC). The train of solitary internal waves shows up as an undulating layer of scattering material in the upper 20m.

Internal waves are generated when an “internal” density interface is disturbed. The ocean is stratified in density, with dense sea-water always underlying less dense (lighter) sea-...