(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1996-08)
Racine, Brian S.
A field experiment was undertaken during July and August of 1995 aimed at
understanding the interaction of acoustic signals with the internal wave field off the
coast of New Jersey. As part of SWARM (Shallow Water Acoustics in a Random
Medium), physical data were collected in 75 m of water near 39°15.34'N, 72°56.59'W
with three thermistor strings, a bottom-mounted ADCP, and yo-yo CTDs. These data
spanned a two-week period of the month-long study. With the exception of a time
following a storm event, during which the generation mechanism near the shelf break was
effectively switched off, large-amplitude (up to 20 meters), rank-ordered groups of
internal solitons were observed traveling through the region approximately every 12.4
hours. These groups of solitons progressed across the shelf with phase speeds of 61.8 ±
14.9 cm/s with a heading of 280 ± 31° T. Two-layer finite-depth theory was tested on
this data and shown to consistently overpredict the phase speed of the internal solitons
within each group. Predictions of horizontal scale, particle velocities, and
displacements were in qualitative agreement with two-layer finite-depth dynamics.
