Exact and approximate probing of sea-bottom

Investigated are two methods for the reconstruction of the acoustic profiles of a plane-stratified structure that model the ocean floor (sediment/subbottom) from reflected fields. The first method is based on a geometrical acoustics approximation. The acoustical parameters of an absorbing layered medium (fluid-solid) are retrieved from the plane-wave reflection coefficients obtained at several incidences and frequencies. Numerical simulations are carried out for two typical configurations; one with high contrasts of parameters and the other with lower contrasts. The second method has initially been developed by S. Coen (1981) for lossless fluid media. The continuous inverse-scattering problem is transferred into the quantum-mechanics domain and solved by a Gel´fand-Levitan technique. Interesting results are obtained for various lossy fluid media and noisy data