Experimental study of geo-acoustic inversion uncertainty due to ocean sound-speed fluctuations.
article
Acoustic data measured in the ocean fluctuate due to the complex time-varying properties of the channel. When measured data are used for model-based, geo-acoustic inversion, how do acoustic fluctuations impact estimates for the seabed properties? In May 1999 SACLANT Undersea Research Center and TNO-Physics and Electronics Laboratory ~FEL!, conducted a shallow-water experiment on the Adventure Bank off the southwest coast of Sicily, Italy to assess the effects of a time-varying ocean on acoustic propagation and geo-acoustic inversion. A favorable area for acoustic propagation was identified which had slight internal wave activity and a weakly range-dependent bathymetry with sand-like bottom properties. Oceanographic and acoustic measurements were performed continuously over a 3-day period. Broadband ~0.2–3.8 kHz! acoustic signals from a bottom-moored source were transmitted over fixed paths and received on a moored vertical hydrophone array. During the transmissions extensive environmental measurements ~e.g., sound speed, current, sea-surface waveheight, etc.! were made to correlate the time-varying environmental and acoustic data. Modeled acoustic data show time variability which agrees with the measurements. Results illustrate severe problems when modeling shallow-water acoustic propagation at ranges beyond a few kilometers in the frequency band considered. Further, the acoustic fluctuations in time caused erroneous time variability in inverted seabed properties.
TNO Identifier
211270
Source
Journal of the Acoustical Society of America, 110(2 Aug. 2001), pp. 769-781.
Pages
769-781
Files
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