Time-angle ocean acoustic tomography using sensitivity kernels: The forward problem

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

1 GIPSA-SIGMAPHY - GIPSA - Signal Images Physique
2 ISTerre - Institut des Sciences de la Terre

Broadband acoustic signals around 1 kHz propagate through shallow water oceanic waveguides of ~100 m in depth and ~2 km in range as multiple ray-like wavefronts. These acoustic arrivals can be characterized by the following observables: travel-time (TT), direction-of-arrival (DOA) and direction-of-departure (DOD). By applying double-beamforming on the point-to-point signals recorded between two source-receiver arrays, the acoustic contribution of each arrival can be separated from the multi-reverberated data and the TT, DOA and DOD observable variations are accurately measured. This study deals with the use of time-angle sensitivity kernels (TASK) to estimate the observable variations induced by sound speed perturbations in the waveguide. This approach is based on the first order Born approximation and takes into account the finite-frequency effects associated with wave propagation. The robustness the TASK approach is analyzed and compared to numerical parabolic equation simulations involving different sound speed perturbations. For example, parameters such as the perturbation location, the value and shape of the perturbation in the waveguide are modified. The combination of several perturbations and the influence of the source-receiver array apertures on the TT, DOA and DOD estimates are also studied.

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

Domaines: Océanographie

Florian Aulanier, Barbara Nicolas, Philippe Roux, Jerome I. Mars. Time-angle ocean acoustic tomography using sensitivity kernels: The forward problem. ICA 2013 - Acoustics 2013 - 21st International Congress on Acoustics - 165th Meeting of the Acoustical Society of America, Jun 2013, Montreal, Canada. pp.005018, ⟨10.1121/1.4798812⟩. ⟨hal-00841118⟩