Horizontal refraction modal tomography of the ocean with mode interactions

The acoustical tomography scheme for inferring a three-dimensional sound-sp eed field within some area based on the measurements of horizontal refracti on angles is reviewed, The numerical simulations made so far were based on the assumption of the adiabaticity of low-frequency mode propagation, In th is paper, an inversion scheme is presented that accounts for the acoustic m ode interaction, We found that, generally, the interaction weakly affects t he horizontal refraction angle, and it can be accounted for by iterations. Numerical simulations for the case of an Atlantic "meddy" corresponding to a strong double-channel stratification are presented, Only three iterations were required to retrieve the exact strong sound-speed-field inhomogeneity within an area of 500 km x 500 km.