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Frequency dependence and intensity fluctuations due to shallow water internal waves
Mohsen Badiey1, Boris G Katsnelson, James F Lynch
1College of Marine and Earth Studies, University of Delaware, Newark, Delaware 19716, USA. badiey@udel.edu
The Journal of the Acoustical Society of America
|August 4, 2007
Summary
This study explores how sound intensity fluctuates with frequency in shallow waters with internal waves. Results show frequency-dependent acoustic scintillation, crucial for understanding underwater sound propagation.
Area of Science:
- Ocean Acoustics
- Underwater Sound Propagation
- Wave Phenomena
Background:
- Shallow water environments present complex acoustic challenges due to factors like internal waves.
- Understanding sound intensity fluctuations (scintillation) is key for acoustic signal processing.
- Anisotropic conditions, such as those caused by internal waves, significantly impact sound propagation.
Purpose of the Study:
- To theoretically and experimentally investigate the frequency dependence of acoustic scintillation in anisotropic shallow water.
- To analyze the behavior of sound intensity fluctuations in the presence of internal waves.
- To examine frequency-dependent modal scintillation within a specific oceanic experiment.
Main Methods:
- Development of a theory based on horizontal rays and vertical modes.
- Application of the theory to analyze acoustic data from the SWARM'95 experiment.
- Measurement and description of the frequency-dependent modal scintillation index.
Main Results:
- The study establishes the azimuthal and frequency behavior of sound intensity fluctuations.
- Demonstrated frequency-dependent acoustic scintillation in shallow water broadband signals.
- Quantified the frequency-dependent modal scintillation index for 30-200 Hz on the New Jersey continental shelf.
Conclusions:
- The developed theory accurately describes sound propagation in anisotropic shallow water with internal waves.
- Internal waves cause significant frequency-dependent scintillation in underwater acoustic fields.
- Findings provide valuable insights for acoustic communication and remote sensing in dynamic ocean environments.
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