Accession Number : AD0688444

Title :   THE PROPAGATION OF SOUND IN IMPERFECT OCEAN SURFACE DUCTS,

Corporate Author : NAVY UNDERWATER SOUND LAB NEW LONDON CONN

Personal Author(s) : Schulkin,Morris

Report Date : 22 APR 1969

Pagination or Media Count : 137

Abstract : In the report, the author attempts to organize a field of knowledge. He reviews the field of the imperfect ocean surface sound duct and makes original contributions of detail where he believes that the greatest and most important needs exist. One of these contributions is the introduction of the concept of statistical reciprocity to explain the observed depth dependence of acoustic intensity within the duct at the higher frequencies. An expression is obtained for surface-coupled attenuation for acoustic propagation in surface ducts, and it is shown that bubble layers, established by wind and breaking waves, can be important in causing absorption losses. The author uses these facts, together with a model of strong acoustic scattering depending on the mean-square slope of the surface irregularities, to account for the acoustic intensity in the shadow zone below the surface duct. The importance of the mean-square slope parameter is also demonstrated by its use to account for wind-speed and acoustic frequency effects observed in acoustic backscattering measurements, especially in the presence of a surface duct. In addition, the author evaluates the importance of wavy thermoclines, drift currents, and the biomass in relation to surface duct propagation. (Author)

Descriptors :   (*UNDERWATER SOUND, SOUND TRANSMISSION), ATMOSPHERIC TEMPERATURE, SEA WATER, THERMOCLINES, ABSORPTION, SCATTERING, DRIFT, OCEAN WAVES, BUBBLES, ATTENUATION, THERMAL PROPERTIES, WIND, CONVECTION(HEAT TRANSFER), ANOMALIES, THESES

Subject Categories : Physical and Dynamic Oceanography
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE