Underwater Acoustic Backscatter from a Model of Arctic Ice Open Leads and Pressure Ridges.

• Main Author: Browne,Michael J
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA
• Format: Text
• Language: English
• Published: 1987
• Subjects: Acoustics; Snow; Ice and Permafrost; *ACOUSTIC SCATTERING; *BACKSCATTERING; *UNDERWATER ACOUSTICS; UNDERICE; RIDGES; PRESSURE; SEA ICE; OPEN WATER; TRAILING EDGES; DIFFRACTION; VIBRATION; SOLIDS; ENERGY CONVERSION; ACOUSTIC MEASUREMENT; MODEL TESTS; PLATES; ACRYLIC RESINS; FLOATING BODIES; SCALE MODELS; LABORATORY TESTS; ARCTIC REGIONS; THESES; Mode conversion; Arctic; Ice; permafrost; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA184693; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA184693

Behavior of monostatic backscatter from Arctic open leads and pressure ridges was studied using scale models in the laboratory under controlled conditions. Experiments were performed in an anechoic tank using pulsed transmissions from underwater point sources to measure the backscatter from several different floating acrylic plate by the selection of the acrylic material, and the geometrical properties of the ice in features were accurately scaled by maintaining the appropriate dimension-to-wavelength ratios. The characteristic behavior of the backscatter was explained using both diffraction theory and mode-conversion concepts. It was generally observed that a significant amount of the incident acoustic energy resulted in solidborne vibrations and propagating waves within the floating plate. The ability of those vibrations to reradiate energy into the water resulted in greater backscatter than predicted from the trailing edge of an open lead and piston-like radiation from pressure rigid models.