Time-angle ocean acoustic tomography using sensitivity kernels: Numerical and experimental inversion results

Florian Aulanier (1) , Barbara Nicolas (1) , Philippe Roux (2) , Romain Brossier (3) , Jerome I. Mars (1)

1 GIPSA-SIGMAPHY - GIPSA - Signal Images Physique
2 Ondes et Structures
3 Risques - Risques

In shallow water acoustic tomography, broadband mid-frequency acoustic waves (1 to 5 kHz) follow multiple ray-like paths to travel through the ocean. Travel-time (TT) variations associated to these raypaths are classically used to estimate sound speed perturbations of the water column using the ray theory. In this shallow water environment, source and receiver arrays, combined with adapted array processing, provide the measurement of directions-of-arrival (DOA) and directions-of-departure (DOD) of each acoustic path as new additional observables to perform ocean acoustic tomography. To this aim, the double-beamforming technique is used to extract the TT, DOA and DOD variations from the array-to-array acoustic records. Besides, based on the first order Born approximation, we introduce the time-angle sensitivity kernels to link sound speed perturbations to the three observable variations. This forward problem is then inverted with the maximum a posteriori method using both the extracted-observable variations and the proposed sensitivity kernels. Inversion results obtained on numerical data, simulated with a parabolic equation code, are presented. The inversion algorithm is performed with the three observables separately, namely TT, DOA and DOD. The three observables are then used jointly in the inversion process. The results are discussed in the context on ocean acoustic tomography.

Mots clés: departure; arrival; angle; direction; time; kernel; sensitivity; underwater; acoustics; ocean; tomography; beamforming

Domaines: Océanographie

Florian Aulanier, Barbara Nicolas, Philippe Roux, Romain Brossier, Jerome I. Mars. Time-angle ocean acoustic tomography using sensitivity kernels: Numerical and experimental inversion results. ICA 2013 - Acoustics 2013 - 21st International Congress on Acoustics - 165th Meeting of the Acoustical Society of America, Jun 2013, Montréal, Canada. pp.005019-005025, ⟨10.1121/1.4798965⟩. ⟨hal-00841121⟩