UNDER-ICE ACOUSTICS AT HIGH FREQUENCIES.

• Main Author: Greene,Charles R.
• Other Authors: GM DEFENSE RESEARCH LABS SANTA BARBARA CALIF SEA OPERATIONS DEPT
• Format: Text
• Language: English
• Published: 1965
• Subjects: (*ARCTIC REGIONS; ACOUSTICS); (*ACOUSTICS; ARCTIC REGIONS); (*ICE; SOUND TRANSMISSION); (*UNDERWATER SOUND; ICE ISLANDS; TEST FACILITIES; HYDROPHONES; OCEANOGRAPHIC EQUIPMENT; OCEANOGRAPHIC DATA; HIGH FREQUENCY; NOISE; NAVAL RESEARCH; Arctic; Knudsen; Barrow; Alaska
• Online Access: http://www.dtic.mil/docs/citations/AD0622823; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0622823

An arctic field expedition was made to drifting station ARLIS IV, 120 miles north of Barrow, Alaska, in April 1965. Under-ice acoustic measurements of ambient noise, reverberation, absorption losses, and propagation were made and supporting data on water temperature, salinity, and ionic constituents were collected. The ambient noise level at 19 kHz exceeded the Knudsen sea state six value for short intervals, but the levels at 34 and 42 kHz were not observed above the Knudsen values for sea state one. An active local ice field accounts for the high levels. Reverberation scattering strengths depend upon the presence of ice keels. Absorption coefficients at frequencies from 20 to 50 kHz are significantly lower than those predicted by Schulkin and Marsh's equation. (Author)