Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation
Thesis (Ph. D. in Applied Ocean Sciences)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), February 2002.
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | eng |
| Published: |
Massachusetts Institute of Technology
2005
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/1721.1/29056 |
| _version_ | 1826196747844583424 |
|---|---|
| author | Becker, Kyle M |
| author2 | George V. Frisk. |
| author_facet | George V. Frisk. Becker, Kyle M |
| author_sort | Becker, Kyle M |
| collection | MIT |
| description | Thesis (Ph. D. in Applied Ocean Sciences)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), February 2002. |
| first_indexed | 2024-09-23T10:37:05Z |
| format | Thesis |
| id | mit-1721.1/29056 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T10:37:05Z |
| publishDate | 2005 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/290562022-01-10T19:02:30Z Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation Becker, Kyle M George V. Frisk. Woods Hole Oceanographic Institution. Joint Program in Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution. Massachusetts Institute of Technology. Department of Ocean Engineering Ocean Engineering. Joint Program in Applied Ocean Physics and Engineering. Woods Hole Oceanographic Institution. Underwater acoustics Ocean bottom Measurement Marine sediments Measurement Inversion (Geophysics) High resolution spectroscopy Thesis (Ph. D. in Applied Ocean Sciences)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), February 2002. Includes bibliographical references (leaves 161-170). Sound propagation in shallow water is highly dependent on the interaction of the sound field with the bottom. In order to fully understand this problem, it is necessary to obtain reliable estimates of bottom geoacoustic properties that can be used in acoustic propagation codes. In this thesis, perturbative inversion methods and exact inverse methods are discussed as a means for inferring geoacoustic properties of the bottom. For each of these methods, the input data to the inversion is the horizontal wavenumber spectrum of a point-source acoustic field. The main thrust of the thesis work concerns extracting horizontal wavenumber content for fully three-dimensionally varying waveguide environments. In this context, a high-resolution autoregressive (AR) spectral estimator was applied to determine wavenumber content for short aperture data. As part of this work, the AR estimator was examined for its ability to detect discrete wavenumbers in the presence of noise and also to resolve closely spaced wavenumbers for short aperture data. As part of a geoacoustic inversion workshop, the estimator was applied to extract horizontal wavenumber content for synthetic pressure field data with range-varying geoacoustic properties in the sediment. The resulting wavenumber content was used as input data to a perturbative inverse algorithm to determine the sound speed profile in the sediment. It was shown using the high-resolution wavenumber estimator that both the shape and location of the range-variability in the sediment could be determined. (cont.) The estimator was also applied to determine wavenumbers for synthetic data where the water column sound speed contained temporal variations due to the presence of internal waves. It was shown that reliable estimates of horizontal wavenumbers could be obtained that are consistent with the boundary conditions of the waveguide. The Modal Mapping Experiment (MOMAX), an experimental method for measuring the full spatial variability of a propagating sound field and its corresponding modal content in two-dimensions, is also discussed. The AR estimator is applied to extract modal content from the real data and interpreted with respect to source/receiver motion and geometry. For a moving source, it is shown that the wavenumber content is Doppler shifted. A method is then described that allows the direct measure of modal group velocities from Doppler shifted wavenumber spectra. Finally, numerical studies are presented addressing the practical issues associated with using MOMAX type data in the exact inversion method of Gelfand-Levitan. by Kyle M. Becker. Ph.D. 2005-09-27T20:20:27Z 2005-09-27T20:20:27Z 2001 2002 Thesis http://hdl.handle.net/1721.1/29056 50499206 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 170 leaves 11937415 bytes 11937169 bytes application/pdf application/pdf application/pdf Massachusetts Institute of Technology |
| spellingShingle | Ocean Engineering. Joint Program in Applied Ocean Physics and Engineering. Woods Hole Oceanographic Institution. Underwater acoustics Ocean bottom Measurement Marine sediments Measurement Inversion (Geophysics) High resolution spectroscopy Becker, Kyle M Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title | Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title_full | Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title_fullStr | Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title_full_unstemmed | Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title_short | Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation |
| title_sort | geoacoustic inversion in laterally varying shallow water experiments using high resolution wavenumber estimation |
| topic | Ocean Engineering. Joint Program in Applied Ocean Physics and Engineering. Woods Hole Oceanographic Institution. Underwater acoustics Ocean bottom Measurement Marine sediments Measurement Inversion (Geophysics) High resolution spectroscopy |
| url | http://hdl.handle.net/1721.1/29056 |
| work_keys_str_mv | AT beckerkylem geoacousticinversioninlaterallyvaryingshallowwaterexperimentsusinghighresolutionwavenumberestimation |