Matched field inversion of geoacoustic properties from towed array
data
in shallow water
O. Lotsberg and S.M. Jesus sjesus@ualg.pt
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.