Underwater Acoustic Scatter from a Model of the Arctic Ice Canopy.

• Main Authors: Denny,Patrick L., Johnson,Kevin R.
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA
• Format: Text
• Language: English
• Published: 1986
• Subjects: Snow; Ice and Permafrost; Acoustics; *ACOUSTIC SCATTERING; *SEA ICE; VELOCITY; SOURCES; CONTRAST; MATERIALS; THESES; ACRYLIC RESINS; BACKSCATTERING; REFLECTION; TRANSMITTANCE; ICE; PULSES; COEFFICIENTS; STRENGTH(GENERAL); PRESSURE; COVERINGS; UNDERWATER ACOUSTICS; ROUGHNESS; FLEXURAL PROPERTIES; LOW FREQUENCY; UNDERWATER SOUND; WAVES; UNDERWATER; ACOUSTIC IMPEDANCE; ARCTIC REGIONS; RIDGES; ACOUSTIC COATINGS; UNDERICE; Arctic; Ice; permafrost; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA176654; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA176654

When low frequency underwater sound interacts with the Arctic ice cover, not only will it be reflected from the plane and scattered in all directions from roughness elements, but it will also be diffracted at leads and reradiated from flexural waves in the ice. These phenomena have been studied in an anechoic tank by pulse transmission from an underwater point source to a series of large floating acrylic plate models, each representing a different type of ice cover. The flexural wave speed, the plate and lead dimensions and the acoustic roughness are accurately scaled, and the specific acoustic impedance contrast is approximately modeled by the selection of the acrylic material. The physical contributors to the gross reflection coefficient and backscattering strength are identified and compared for models of a plane ice layer, an Arctic ice pressure ridge, edges of leads, and a rubble field of ice. Keywords: Underwater Acoustics; Scatter, Backscatter; Arctic Ice; Reflection Coefficient; Flexural Waves; Theses.