LARGE-AMPLITUDE INTERNAL SOLITON PACKETS IN THE CENTRAL BAY OF BISCAY

In the Bay of Biscay, large-amplitude internal tides result from the interaction of surface tides with steep bottom topography. Near the shelf break, the troughs of the internal tides are associated with packets of large nonlinear internal waves or "solitons". By using an Acoustic Doppler Current Profiler, we here demonstrate that a similar phenomenon occurred at a considerable distance (150 km) from the shelf break, and make a detailed examination of the dramatic changes in velocity structure which accompanied the passage of the soliton packets. In particular, horizontal and vertical velocities exceeding, respectively, 60 and 16 cm s-1 were observed. A novel mechanism is proposed for the possible local generation of such large-amplitude solitons so far from topography. © 1990.