Se. Dosso et al., ESTIMATION OF OCEAN-BOTTOM PROPERTIES BY MATCHED-FIELD INVERSION OF ACOUSTIC FIELD DATA, IEEE journal of oceanic engineering, 18(3), 1993, pp. 232-239
Properties of the ocean bottom, including bathymetry and geoacoustic p
arameters such as sound speed, density and attenuation, are required f
or reliable acoustic propagation modeling and matched-field source loc
alization. Bottom properties can be difficult to measure directly; how
ever, inversion procedures hold much promise for estimating their valu
es from acoustic field measurements. The inversion can be formulated a
s an optimization problem by assuming a discrete model of unknown para
meters and a bounded search space for each parameter. The optimization
then involves finding the set of parameter values which minimizes the
mismatch between the measured acoustic field and modeled replica fiel
ds. Since the number of possible models can be extremely large, we hav
e employed the method of simulated annealing which provides an efficie
nt optimization that avoids becoming trapped in suboptimal solutions.
The matching fields are computed using a normal mode model. In inversi
ons for range-dependent parameters, the adiabatic approximation is emp
loyed: this allows mode values to be pre-computed for a grid of parame
ter values and stored in ''look-up'' tables for fast reference, which
greatly improves computational efficiency. Synthetic inversion example
s are presented for realistic range-independent and range-dependent en
vironments.