The interaction of Sound and Tides

Y. Stephan and X. Demoulin ,
Centre Militaire Oceanographique - SHOM, Brest, France
T. Folegot
Atlantide, Brest, France
S.M. Jesus
UCEH - Universidade do Algarve, Faro, Portugal
M.B. Porter
Dep. of Applied Mathematics, New Jersey Institute of Technology, NJ, USA
E. Coelho
Instituto Hidrografico, Lisboa, Portugal

Comments: download pdf file .
Ref.: in Experimental Acoustics Inversion Methods for Exploration of the Shallow Water Environment, Caiti, Hermand, Jesus and Porter (eds.), KLUWER, (ISBN 0-7923-6305-1) pp. 107-123, March 1999.

Abstract : This paper presents an overview of the experiment INTIMATE'96, carried out in June 1996 on the continental shelf off the coast of Portugal and discusses the effects of internal tides on the acoutic propagation. A towed broadband acoustic source and a 4-hydrophone vertical array were used. Acoustic data were collected for 5 days, including legs where the source ship was moving and legs with the ship on station. Intensive environmental surveys (XBT, CTD, bottom and hull mounted ADCP, thermistor chain, bathymetry, geoacoustic characteristics of the sediments) were also conducted. The central results of acoustic data processing is that several effects of the environment, including bottom influence, source range and depth and internal tides effects, can be clearly seen on the signals and they can be processed separately. The acoustical effects of tides enables to perform inversion with simple and fast methods. The results of INTIMATE'96 confirm the efficiency of broadband analysis on a single hydrophone to infer the geophysical environment.

ACKNOWLEDGMENT: this work was partially supported by project INTIMATE from FCT (Portugal).