Accession Number : AD0782274

Title :   A Review of Low-Frequency Sound Attenuation in the Ocean.

Descriptive Note : Technical memo.,

Corporate Author : NAVAL UNDERWATER SYSTEMS CENTER NEWPORT R I

Personal Author(s) : Thorp,W. H. ; Browning,D. G. ; Jones,E. N. ; Mellen,R. H.

Report Date : 18 JUN 1971

Pagination or Media Count : 9

Abstract : The trend to lower sonar frequencies following WW 2 has revealed the existence of two and possibly more regimes of excess attenuation of sound in the oceans. The first of these, identified as a relaxation absorption caused by the MgSO4 content in sea water and, below 100 kHz, results in an increase in the absorption coefficient over fresh water by roughly a factor of 20. The second shows a further increase by a factor of 10 below 1 kHz. A number of hypotheses, including a second relaxation, have been proposed to explain the excess attenuation anomaly. Experimental techniques, data analysis, and mathematical models are discussed. (Author)

Descriptors :   *Underwater sound, *Acoustic attenuation, Sea water, Low frequency, Sonar signals, Regression analysis, Magnesium compounds, Sulfates

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE