Accession Number : AD0722640

Title :   Volume-Scattering-Strength Dependence on Depth and Frequency in the Pacific Ocean off San Francisco,

Corporate Author : DEFENCE RESEARCH ESTABLISHMENT PACIFIC VICTORIA (BRITISH COLUMBIA)

Personal Author(s) : Scrimger,J. A. ; Turner,R. G.

Report Date : 29 JUL 1970

Pagination or Media Count : 10

Abstract : A time series of measurements of volume scattering was made in the N. E. Pacific Ocean at a site approximately 55 miles west of Pt. Reyes (near San Francisco). The technique involved the firing of small explosive charges close to a receiving hydrophone and monitoring the broad-band scattered returns originating nearby (approximately 100-ft radius). Lowering the hydrophone-charge combination to various depths enabled the scattering characteristics in the top 2100 ft of the ocean to be examined. The data are presented as spectra of scattering strength versus frequency to 10 evenly spaced depths between 200 and 2000 ft and also as a set of eight profiles of scattering strength versus depth in each of four octave frequency bands between 0.625 and 10kHz. These profiles are obtained in the course of a 30-min lowering of the equipment--eight of which were carried out between 0600 PST (about 1 1/2 h before dawn) and 2000 PST (about 2 h after sunset). Scattering-strength profiles were integrated against depth to give column scattering strength values which are displayed as a function of time. In addition, a comparison was made between integrated scattering strength versus depth profiles obtained both from a scattering strength versus depth profile and from a surface-fired change. (Author)

Descriptors :   (*ECHO RANGING, PACIFIC OCEAN), (*SOUND RANGING, UNDERWATER EXPLOSIONS), UNDERWATER SOUND, HYDROPHONES, DEPTH FINDING, SHOCK WAVES, TIMING DEVICES, VERY LOW FREQUENCY, CALIFORNIA, CANADA

Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE