M.B. Porter porter@mpl.ucsd.edu
Dep. of Applied Mathematics
New Jersey Institute of Technology, NJ, USA
Y. Stephan stephan@shom.fr
X. Demoulin demoulin@shom.fr
Centre Militaire d'Oceanographie - SHOM
Brest, France
S.M. Jesus sjesus@ualg.pt
UCEH - Universidade do Algarve, Faro, Portugal
E. Coelho Instituto Hidrografico
Lisboa, Portugal
Comments: download pdf file .
Ref.: in Undersea Technology'98, IEEE Ocean Engineering Society, Tokyo, Japan,
1998.
Abstract: In the summer of 1996, an experiment was conducted off the coast of Portugal
to study the effects of internal tides on sound propagation. This experiment - called INTIMATE'96
(Internal Tide Investigation by Means of Acoustic Tomography Experiments) - has provided a great
deal of insight about the variability of pulse transmission over space and time. In contrast
to a common view of shallow-water propagation as complicated and unpredictable, we find a steady
pattern of echoes. The echo-pattern stretches and shrinks in a systematic way with the tides and
allows us to infer the components of the first oceanographic modes. We also used the echo-pattern to
track the source over a perido of several days. During this period the isotherms in the ocean
wavered by 20 m as a result of the tides, providing a challenge for model-based tracking. We will
discuss these acoustic results with emphasis on the source tracking.
ACKNOWLEDGMENT: this work was partially supported by PRAXIS XXI program under project 2./2.1/MAR/1695/95.