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Passive ocean acoustic tomography in shallow water
Fenghua Li1, Xishan Yang1, Yanjun Zhang1
1State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing, 100190, China.
The Journal of the Acoustical Society of America
|June 3, 2019
Summary
Researchers accelerated the extraction of empirical Green's functions (EGFs) from ocean ambient noise using array signal processing. This advancement enables faster ocean sound speed profile (SSP) inversion for improved acoustic tomography applications.
Area of Science:
- Oceanography
- Acoustics
- Signal Processing
Background:
- Empirical Green's function (EGF) estimation from ocean ambient noise offers an alternative to traditional ocean acoustic tomography.
- Long recording times are typically needed for high signal-to-noise ratio (SNR) EGFs, limiting practical applications.
Purpose of the Study:
- To accelerate the convergence rate of EGFs between two horizontally separated arrays using array signal processing.
- To enable rapid inversion of ocean sound speed profiles (SSPs) for shallow water environments.
Main Methods:
- Cross-correlation functions of ambient ocean noise were analyzed.
- Array signal processing techniques were applied to enhance EGF convergence.
- Data assimilation methods were combined with extracted EGFs for SSP inversion.
Main Results:
- The study successfully accelerated EGF extraction, reducing the time required for analysis.
- Ocean sound speed profiles (SSPs) were inverted every 2 hours in shallow water.
- Reconstructed SSP variations showed reasonable agreement with an average variance of 1.14 m/s over three months.
Conclusions:
- Array signal processing significantly improves the efficiency of EGF estimation from ocean noise.
- Rapid SSP inversion is achievable, enhancing the feasibility of acoustic tomography in dynamic shallow water environments.
- The method provides a valuable tool for monitoring oceanographic changes using acoustic data.
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