A Comparison between Acoustic Reverberation Structures at 87.5 kHz and Internal Waves

Abstract

Reverberation data at 87.5 kHz were obtained with a narrow-beam echo sounder from R/P FLIP in January and June 1977 off southern California. Analysis of these data shows that backscattering below the wind-mixed layer was due primarily to discrete point scatterers, which had target strengths ranging from -38 to -73 dB and densities of 0.05 to 50 individuals per 1000 cu m. Based upon these characteristics, the identities of the scatterers are probably swimbladder fish, and possibly squid and siphonophores. Backscattering from smaller organisms has been observed as patches or as a limited number of scattering layers. A visual comparison between scatterer motions and isotherm depth fluctuations showed excellent correlation in terms of both phase and amplitude. Minimum total wave amplitudes as small as three meters were observed. It is suggested that this depth resolution might be improved with better data processing techniques and increased system performance.

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Document Details

Document Type
Technical Report
Publication Date
Oct 17, 1977
Accession Number
ADA050961

Entities

People

  • G. T. Kaye

Organizations

  • Scripps Institution of Oceanography

Tags

Communities of Interest

  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Backscattering
  • Engineering
  • Frequency
  • Geography
  • Internal Waves
  • Isotherms
  • Measurement
  • Military Research
  • Naval Warfare
  • Navy
  • New York
  • Oceanography
  • Oceans
  • Orientation (Direction)
  • Scattering
  • Temperature Gradients
  • Test And Evaluation

Readers

  • Acoustical Oceanography.
  • Oceanography.