Some Measurements of Acoustic Normal Mode Propagation in Shallow Water

Abstract

Experiments were conducted in the northern Gulf of Mexico during July 1969 and March 1970 to study propagation characteristics of acoustic normal modes. This shallow-water area had a constant depth (31 plus or minus 2.5 m) over a propagation path of at least 20 km along a bearing line of 285 degrees T. Short-pulse, 3 cycle signals were emitted from 400- or 750-Hz center frequency sources. The vertical distributions of pressure amplitude of each of the two lowest order normal modes of these signals, measured by a vertical line of hydrophones, agreed well with distributions calculated by computer using a two- layer fluid model. Temporal variations of modal intensity averaged over depth for both the first and the second modes were observed for 7-min runs.

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Document Details

Document Type
Technical Report
Publication Date
Nov 16, 1972
Accession Number
AD0753200

Entities

People

  • A. E. Schuetz

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies
  • Sensors

DTIC Thesaurus Topics

  • Acoustic Propagation
  • Acoustics
  • Amplitude
  • Computer Programs
  • Cross Correlation
  • Dispersions
  • Filtration
  • Frequency
  • Group Velocity
  • Hydrophones
  • Intensity
  • Measurement
  • Military Research
  • Recording Systems
  • Shallow Water
  • Spatial Filtering
  • Velocimeters

Readers

  • Acoustical Oceanography.
  • Atmospheric Science/Meteorology
  • Spectroscopy.