ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1pAO10. Ocean structure inversion by horizontal refraction tomography.

A. G. Voronovich

E. C. Shang

CIRES, Univ. of Colorado/NOAA/Environ. Technol. Lab., 325 Broadway, Boulder, CO 80303

Numerical simulations for the horizontal refraction tomography (HRT) proposed previously [A. G. Voronovich and E. C. Shang, 2851(A) (1994)] were conducted. HRT is based on measurements of horizontal refraction angles (HRA) related to different acoustic modes. HRA are measured with the help of two distant ocean interferometers (each one consists of a pair of long mode resolving vertical arrays separated about 10 km apart). The signal is produced by tonal towed acoustic source. Both model eddy and real oceanic eddy of 100 kmx100 km scale measured in Canary Basin were used for simulations. The 3-D tomography inversion proceeded in two stages: (1) retrieving the values of propagation constants in the knots of a horizontal rectangular greed (linear 2-D problem) and (2) reconstruction of the sound-speed profile (SSP) in each knot (1-D nonlinear problem). Up to 81 values of propagation constants for each mode were retrieved in both cases. Then SSP were calculated in each knot with the help of a special invariant-imbedding based procedure. With error-free simulated HRA data, SSPs were exactly reconstructed. The effect of errors on tomography inversion and requirements to the accuracy of phase measurements were also estimated. [Work supported by ONR.]