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.]