GEOACOUSTIC INVERSION TECHNIQUES UTILIZING ACOUSTIC VECTOR SENSORS AND RESULTS FROM THE MONTEREY BAY SHELF
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Authors
Geddes Lemos Guarino, Alexandre
Subjects
geoacoustic inversion
vector sensors
time-warping. dispersion curves
vector sensors
time-warping. dispersion curves
Advisors
Cristi, Roberto
Smith, Kevin B.
Joseph, John E.
Godin, Oleg A.
Gemba, Kay L.
Deal, Thomas J., Naval Undersea Warfare Center, Newport Division
Date of Issue
2022-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
The propagation of acoustic waves in shallow water is affected by the seabed properties. Estimating these properties in situ using acoustics is an area of research that has been in development for decades, and many techniques have been proposed using pressure-only sensors. In recent years, vector sensors have been adopted to expand the capabilities of geoacoustic inversion. This dissertation builds upon the findings of Guarino et al. reported in the Journal of Theoretical and Computational Acoustics and in the Proceedings of the 24th International Congress on Acoustics, 24–28 October 2022. It is shown that the combination of pressure and vertical velocity channels of a vector sensor can improve both the estimation of bottom attenuation coefficient, using the modal phase difference approach, and geoacoustic parameters like sound speed and density, using the multichannel average of dispersion curves. In addition, Time-warping, which is a broadly used technique for modes separation, is improved with the inclusion of a band-pass filter masking approach in the time-frequency analysis. Finally, this work suggests that waveform matching should be used as a preliminary step in dispersion curve analysis to improve inversion performance, or even be the primary choice when a vector sensor is available. The results use data collected in Monterey Bay in 2019.
Type
Dissertation
Description
Series/Report No
Department
Engineering Acoustics Academic Committee (EAAC)
Organization
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NPS Report Number
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Citation
Distribution Statement
Approved for public release. Distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.