Measurements of high-frequency acoustic scattering from glacially eroded rock outcrops

Author
Olson, Derek R.
Lyons, Anthony P.
Sæbø, Torstein Olsmo
Date Issued
2016
Keywords
Syntetisk apertur-sonar
Geoakustikk
Permalink
http://hdl.handle.net/20.500.12242/593
https://publications.ffi.no/123456789/593
DOI
10.1121/1.4945589
Collection
Articles
Description
Olson, Derek R.; Lyons, Anthony P.; Sæbø, Torstein Olsmo. Measurements of high-frequency acoustic scattering from glacially eroded rock outcrops. Journal of the Acoustical Society of America 2016 ;Volum 139.(4)
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Abstract
Measurements of acoustic backscattering from glacially eroded rock outcrops were made off the coast of Sandefjord, Norway using a high-frequency synthetic aperture sonar (SAS) system. A method by which scattering strength can be estimated from data collected by a SAS system is detailed, as well as a method to estimate an effective calibration parameter for the system. Scattering strength measurements from very smooth areas of the rock outcrops agree with predictions from both the small-slope approximation and perturbation theory, and range between −33 and −26 dB at 20° grazing angle. Scattering strength measurements from very rough areas of the rock outcrops agree with the sine-squared shape of the empirical Lambertian model and fall between −30 and −20 dB at 20° grazing angle. Both perturbation theory and the small-slope approximation are expected to be inaccurate for the very rough area, and overestimate scattering strength by 8 dB or more for all measurements of very rough surfaces. Supporting characterization of the environment was performed in the form of geoacoustic and roughness parameter estimates.
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