The Reflection of Acoustic Waves in Sea Water from an Ice Covered Surface.
Measurements of the acoustic reflectivity of the lower surface of sea ice were made at several locations in the channels of the Canadian Arctic Archipelago from 1971 to 1973. The distance between the projector and hydrophone was typically 100 to 300 m; the grazing angle at the ice-water interface ra...
Main Authors: | , |
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Other Authors: | |
Format: | Text |
Language: | English |
Published: |
1977
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Online Access: | http://www.dtic.mil/docs/citations/ADA047298 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA047298 |
Summary: | Measurements of the acoustic reflectivity of the lower surface of sea ice were made at several locations in the channels of the Canadian Arctic Archipelago from 1971 to 1973. The distance between the projector and hydrophone was typically 100 to 300 m; the grazing angle at the ice-water interface ranged up to 30 deg, and the frequency limits were 200 Hz and 20,000 Hz. The measured reflectivities show large excursions from unity. Reflectivities of -15 dB are not uncommon in spite of the uniform flatness of the ice-water interface and in spite of the shallowness of the grazing angle. However, a calculation based on Kirchhoff's Integral Theorem and involving an integration over the interface indicates that the observed undulation in the ice-water interface is sufficient to account for the observed results. |
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