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Ocean bottom profiling with ambient noise: a model for the passive fathometer
James Traer1, Peter Gerstoft, William S Hodgkiss
1Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093-0238, USA. jtraer@ucsd.edu
The Journal of the Acoustical Society of America
|April 12, 2011
Summary
This study models passive fathometer responses to ocean noise, revealing how surface and discrete noise sources create sub-bottom reflector data. Techniques like minimum variance distortionless response (MVDR) steering and beamforming can mitigate noise interference for clearer seabed imaging.
Area of Science:
- Ocean acoustics
- Geophysical signal processing
- Underwater acoustics
Background:
- Passive fathometers are crucial for seabed exploration.
- Ocean noise sources, including surface and discrete signals, can interfere with acoustic measurements.
- Understanding noise propagation in ideal waveguides is essential for accurate sub-bottom profiling.
Purpose of the Study:
- To develop a comprehensive model for passive fathometer response to various ocean noise types.
- To analyze how ocean surface noise, discrete noise, and uncorrelated noise affect fathometer signals.
- To identify methods for mitigating noise-induced artifacts in passive fathometer data.
Main Methods:
- Modeling the passive fathometer response in an ideal waveguide.
- Analyzing the contribution of ocean surface noise via cross-correlation of vertical multipaths.
- Investigating the impact of discrete noise sources and seabed critical angles.
- Applying minimum variance distortionless response (MVDR) steering and beamforming techniques.
Main Results:
- Ocean surface noise directly contributes to sub-bottom reflector depth estimation.
- Discrete noise sources can generate multiple peaks, potentially obscuring seabed reflections.
- Seabed critical angles can cause spatial discontinuities, leading to spurious peaks.
- MVDR steering and beamforming effectively attenuate noise-induced peaks.
Conclusions:
- The developed model accurately describes passive fathometer responses to complex ocean noise environments.
- Signal processing techniques are vital for enhancing the clarity of sub-bottom data obtained from passive fathometers.
- Accurate seabed imaging requires careful consideration and mitigation of acoustic noise interference.
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