Accession Number : AD0475320

Title :   ACOUSTIC DETECTION OF MICROBUBBLES AND PARTICULATE MATTER NEAR THE SEA SURFACE

Descriptive Note : Master's thesis

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Buxcey, Stanley ; McNeil, James E ; Marks, Robert H

PDF Url : AD0475320

Report Date : Jan 1965

Pagination or Media Count : 413

Abstract : A pulse-echo system using an electrostatic transducer and steel reflector was operated over the frequency range 24-192 Kcps in the sea and in the laboratory. Excell attenuations from 0.15 to 1.1 db/M due to absorption and scattering by inhomogeneities were made over the full frequency range with a maximum error of less than 0.05 db/meter. Backscattering at sea was detected in the frequency range 24-60 Kcps with an average scattering cross-section per unit volume of 400 sq cm/ cu m at a depth of 10 feet. Scattering as not detected above 60 Kcps. Variation of sound velocity with frequency was measured from 24- 192 Kcps. The accuracy of these values was 0.03% for frequencies over 40 Kcps. Results are compared and it is postulated that; (1) below 60 Kcps the absorption and scattering was due to microbubbles of radius greater than 50 microns, and (2) above 60 Kcps minute plankton caused absorption without significant scattering.

Descriptors :   *ACOUSTIC DETECTORS, *BUBBLES, *OCEANS, *SEA WATER, ATTENUATION, COMPUTER PROGRAMMING, ECHO RANGING, ELECTROACOUSTIC TRANSDUCERS, ELECTRONIC EQUIPMENT, EXPERIMENTAL DATA, LOW FREQUENCY, PARTICLES, PULSES, SCATTERING, SENSITIVITY, SOUND, SURFACES, VERY LOW FREQUENCY

Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE