A. G. Voronovich
E. C. Shang
CIRES, Univ. of Colorado/NOAA/ETL, 325 Broadway, Boulder, CO 80303
A scheme of acoustical tomography of the ocean based on measurements of horizontal refraction angles associated with different acoustic modes has been developed recently [A. G. Voronovich and E. C. Shang, J. Acoust. Soc. Am. (to be published)]. Retrieving the 3-D structure of meso-scale inhomogeneities of sound speed proceeds in this case in two steps: (1) determining propagation constants of different modes in the horizontal plane (2-D linear tomography), and (2) retrieving sound-speed profiles basing on a known set of propagation constants at each horizontal point (1-D nonlinear tomography). This tomography scheme was successfully tested in a numerical simulation based on an assumption of adiabaticity of acoustic propagation. ``Splitting'' of the inverse problem into two stages appeared to be very effective computationally. The present investigation extends this tomography scheme for the situations when the mode's interaction should be taken into account. Now, retrieving the set of propagation constants proceeds iteratively and includes data on sound-speed profiles found at the previous step. For a relatively weak mode interaction which can be considered in a perturbative manner iterations converge after a few steps and the inversion scheme remains very effective. Typical parameters of mesoscale inhomogeneities which can be handled by this iterative approach are estimated. [Work supported by ONR.]