Accession Number:

ADA193382

Title:

Arctic Ice Attenuation Model Study

Descriptive Note:

Final technical rept.

Corporate Author:

OMNI ANALYSIS INC WATERFORD CT

Personal Author(s):

• Mellen, R. H.
• Scheifele, P. M.

Report Date:

1987-09-01

Pagination or Media Count:

36.0

Abstract:

Underwater acoustic propagation in the Arctic Ocean is characterized by a refractive surface-channel with a rough boundary. Acoustic scattering estimates, based on free-surface theory, have proven low by more than a factor of two in forward-scatter loss and low by 20 dB or more in backscatter strength. Failure to account for either attenuation or backscattering indicates that impedance effects must be involved. The ice layer is modeled as a uniform elastic solid. Perturbation analysis shows scattering from slopes as well as displacements. Displacements produce piston-like reradiation in addition to the usual vertical-dipole type associated with free surfaces. The rocking horizontal dipole produced by slopes is evidently a significant mechanism at the lower frequencies. However, estimates of both attenuation and backscatter strength are much too low compared with experimental data. Keywords Acoustic attenuation Ice-water interface slope Acoustic reflectivity Underice roughness, Acoustic velocity Low-frequency.

Descriptors:

• *ACOUSTIC ATTENUATION
• *ACOUSTIC SCATTERING
• *BACKSCATTERING
• ACOUSTIC IMPEDANCE
• ACOUSTIC REFLECTION
• ACOUSTIC VELOCITY
• ARCTIC OCEAN
• ATTENUATION
• BOUNDARIES
• DISPLACEMENT
• ELASTIC PROPERTIES
• ESTIMATES
• EXPERIMENTAL DATA
• FORWARD SCATTERING
• ICE
• INTERFACES
• LAYERS
• LOSSES
• LOW FREQUENCY
• PERTURBATIONS
• ROUGHNESS
• SCATTERING
• SLOPE
• SOLIDS
• SOUND TRANSMISSION
• STRENGTH(GENERAL)
• SURFACES
• THEORY
• TRANSFER FUNCTIONS
• UNDERICE
• UNDERWATER ACOUSTICS
• WATER

Subject Categories:

• Soil Mechanics
• Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE