Dynamic tomography of a gravity wave at the interface of an ultrasonic fluid waveguide

• Main Authors: Bonneau, Lenaic, Marandet, Christian, Roux, Philippe, Nicolas, Barbara, Mars, Jérôme
• Format: Conference Proceeding
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.3654859

Based on single-scattering effects, the diffraction-based sensitivity kernels which make the link between the acoustic perturbations and the medium fluctuations have been extensively studied. This research has been recently extended to perturbations at the air–water interface in an ultrasonic waveguide that scales down with a 1-km-long, 50-m-deep ocean acoustic channel in the kilohertz regime. Using array processing between two source-receiver arrays, the sensitivity kernel for both time and amplitude has been experimentally measured and theoretically calculated for each acoustic echo reverberated in the waveguide in response to a small and local surface elevation. In the present work, an ultrasonic experiment is performed during which the waveguide transfer matrix between the source-receiver arrays is recorded 50 times per second while a low-amplitude gravity wave is generated at the water–air interface. The acoustic inversion performed from the surface sensitivity kernels permits to follow the gravity wave dynamics at any point of the surface between the source and the receiver arrays.