HAL : hal-00625344, version 1

DOI : 10.1121/1.3621271

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Journal of the Acoustical Society of America 130, 3 (2011) 1232-1241

Travel-time tomography in shallow water: Experimental demonstration at an ultrasonic scale

Philippe Roux (  Auteur correspondant ) 1, Ion Iturbe 2, Barbara Nicolas 2, Jean Virieux 1, Jerome I. Mars 2

ISTERRE Collaboration(s)

(07/07/2011)

Acoustic tomography in a shallow ultrasonic waveguide is demonstrated at the laboratory scale between two source-receiver arrays. At a 1/1 000 scale, the waveguide represents a 1.1-km-long, 52- m-deep ocean acoustic channel in the kilohertz frequency range. Two coplanar arrays record the transfer matrix in the time domain of the waveguide between each pair of source-receiver transducers. A time-domain, double-beamforming algorithm is simultaneously performed on the source and receiver arrays that projects the multi-reflected acoustic echoes into an equivalent set of eigenrays, which are characterized by their travel times and their launch and arrival angles. Travel-time differences are measured for each eigenray every 0.1 s when a thermal plume is generated at a given location in the waveguide. Travel-time tomography inversion is then performed using two forward models based either on ray theory or on the diffraction-based sensitivity kernel. The spatially resolved range and depth inversion data confirm the feasibility of acoustic tomography in shallow water. Comparisons are made between inversion results at 1 and 3 MHz with the inversion procedure using ray theory or the finite-frequency approach. The influence of surface fluctuations at the air- water interface is shown and discussed in the framework of shallow-water ocean tomography.

1 :	Institut des sciences de la Terre (ISTerre)
	CNRS : UMR5275 – IFSTTAR – Université de Savoie – Université Joseph Fourier - Grenoble I – INSU – OSUG – Institut de recherche pour le développement [IRD] : UR219
2 :	Grenoble Images Parole Signal Automatique (GIPSA-lab)
	CNRS : UMR5216 – Université Joseph Fourier - Grenoble I – Université Pierre-Mendès-France - Grenoble II – Université Stendhal - Grenoble III – Institut Polytechnique de Grenoble - Grenoble Institute of Technology

Équipe de recherche : Ondes et structures Risques SIGMAPHY

Domaine

:

Sciences de l'ingénieur/Traitement du signal et de l'image Informatique/Traitement du signal et de l'image

Mots Clés : shallow-water ocean tomography – Travel-time tomography inversio – Ultrasonic scale – acoustic signal processing – acoustic tomography – acoustic waveguides – echo – inverse problems – oceanographic techniques – signal sampling – ultrasonic transducers – underwater acoustic propagation

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Contributeur : Jerome Mars <>

Soumis le : Mercredi 21 Septembre 2011, 13:09:05

Dernière modification le : Mardi 4 Décembre 2012, 14:27:41