Tidal effects on source inversion

M.B. Porter porter@mpl.ucsd.edu
Dep. of Applied Mathematics, New Jersey Institute of Technology, NJ, USA
S.M. Jesus sjesus@ualg.pt
UCEH - Universidade do Algarve, Faro, Portugal
Y. Stephan and X. Demoulin stephan@shom.fr , demoulin@shom.fr
Centre Militaire Oceanographique - SHOM, Brest, France
E. Coelho oceanografia@hidrografico.pt
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. 19-38, March 1999.

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 ans shrinks in a systematic way with tides and allows us to infer the components of the first few oceanographic modes. We also used the echo-pattern to track the source over a period of several days. During this period the isotherms in the ocean wavered by 20 m as a results 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 project INTIMATE from FCT (Portugal).