Abstract:
Measurements of horizontal refraction angles associated with horizontal refraction of different acoustic modes can be used for inferring 3-D ocean inner structure [A. G. Voronovich and E. C. Shang, J. Acoust. Soc. Am. 98, 2708--2716 (1995)]. Numerical simulations demonstrated that the corresponding inversion scheme works very well for adiabatic propagation. It was also shown that the nonadiabatic case can be incorporated into the inversion scheme when mode interactions can be approximately accounted for by modifying local values of propagation constants of modes. In the present investigation, mode interaction is taken into account in a much more realistic ``Nx2-D'' approximation (only relatively weak azimuth coupling is neglected). A new exact algorithm was used for the calculation of mode interactions in the plane of propagation. Numerical simulations showed that in many cases, the effect of mode interactions on horizontal refraction is rather weak and can be taken into account by rapidly converging iterative procedure. The results of tomography reconstruction of mesoscale inhomogeneities typical for the Pacific are demonstrated. [Work supported by ONR.]