Reflection and Scattering of Acoustic Rays Computed for Parabolic Ice Keel Models.

• Main Author: Gordon, D F
• Other Authors: NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA
• Format: Text
• Language: English
• Published: 1988
• Subjects: Acoustics; Physical and Dynamic Oceanography; *SEA ICE; *ACOUSTIC SCATTERING; *UNDERWATER ACOUSTICS; ANGLES; ARCTIC REGIONS; BACKSCATTERING; COEFFICIENTS; CROSS SECTIONS; DISTRIBUTION; ELASTIC PROPERTIES; GRAZING; LONG RANGE(TIME); PARABOLAS; SLOPE; SOLIDS; SOUND TRANSMISSION; STRENGTH(GENERAL); SURFACE PROPERTIES; THEORY; ACOUSTIC REFLECTION; Ice keels; PE61152N; WU711ZT69; Arctic; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA193898; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA193898

Coefficients are computed for ray reflection and scattering from a model of a set of keels. The model is a collection of parallel ice keels that are of parabolic cross section. The size of the keels and the spacing between them are drawn from random distributions. The keels are also widened by a random factor to simulate oblique incidence on nonparallel keels. Rays are permitted to reflect from and refract through keels according to the interface properties between fluids and elastic solids. A large number of rays are directed toward the keel model and, upon emergence, are sorted into angular bins to determine scattering strength versus direction. Scattering coefficients have a dominant lobe near the secular direction. This is shown to result from the shape of the curve of reflection versus grazing angle. Very little backscatter occurs, a result of the limited slope angle of the parabolic keel models. Keywords: Arctic acoustics; Acoustic propagation; Ray theory; Sea ice; Reflection coefficients; Scattering coefficients; Ice keels.