Matched field inversion of geoacoustic properties from towed array data in shallow water

O. Lotsberg and S.M. Jesus
UCEH- Universidade do Algarve
Campus de Gambelas
PT-8000 Faro, Portugal

Comments: download pdf file .
Ref.: 3rd European Conf. Underwater Acoustics (ISBN 960-85709-2-1),  p.601-606, Heraklion, Greece, 1996.

Abstract: This work reports the inversion results obtained on part of the data collected during a sea trial that took place in the Panteleria  Bank, south of Sicily, in March 1994. During that experiment the source was emitting acoustic tones at frequencies between 100 and 200 Hz and the towed array had 40 hydrophones at 4 m spacing. The array shape was measured continously during the trial, and was considered known in the forward model. After adjusting the forward model to correct water depth and layer thickness, inversion for p-velocity gave consistent results in some part of the survey when compared to the available ground truth measurements made during the cruise. The results obtained at frequencies around 150 Hz have a higher accuracy and are more consistent over time than those obtained at lower frequencies. The results show also that a mismatched forward model will lead to, sometimes consistent, biased inversion results. As expected from simulation studies, shear velocities have very little influence on the acoustic field, and had no influence on the inversion.

ACKNOWLEDGMENT: this work was partially supported by the EU project MAS2-CT920022.