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

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 a...

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Bibliographic Details
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
Description
Summary: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.

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