Book contents
- Frontmatter
- Contents
- Preface
- Notation
- 1 THE TOMOGRAPHY PROBLEM
- 2 THE FORWARD PROBLEM: RANGE-INDEPENDENT
- 3 CURRENTS
- 4 THE FORWARD PROBLEM: RANGE-DEPENDENT
- 5 OBSERVATIONAL METHODS
- 6 THE INVERSE PROBLEM: DATA-ORIENTED
- 7 THE INVERSE PROBLEM: MODEL-ORIENTED
- 8 THE BASIN SCALE
- EPILOGUE. THE SCIENCE OF OCEAN ACOUSTIC TOMOGRAPHY
- APPENDIX
- References
- Index of Authors & Subjects
6 - THE INVERSE PROBLEM: DATA-ORIENTED
Published online by Cambridge University Press: 04 May 2010
- Frontmatter
- Contents
- Preface
- Notation
- 1 THE TOMOGRAPHY PROBLEM
- 2 THE FORWARD PROBLEM: RANGE-INDEPENDENT
- 3 CURRENTS
- 4 THE FORWARD PROBLEM: RANGE-DEPENDENT
- 5 OBSERVATIONAL METHODS
- 6 THE INVERSE PROBLEM: DATA-ORIENTED
- 7 THE INVERSE PROBLEM: MODEL-ORIENTED
- 8 THE BASIN SCALE
- EPILOGUE. THE SCIENCE OF OCEAN ACOUSTIC TOMOGRAPHY
- APPENDIX
- References
- Index of Authors & Subjects
Summary
Introduction
The preceding chapters have demonstrated that a variety of measurable acoustic features, including ray travel time, amplitude, and inclination, mode group velocity, and carrier phase, are integral functions of the oceanic sound-speed field. As discussed in previous chapters, sound-speed is intimately related to the oceanic density field, which is, in turn, a dynamic variable related to the oceanic flow field. Under many circumstances, knowledge of the density field alone is adequate to compute the oceanic flow field to a high degree of approximation. Reciprocal tomographic measurements are direct weighted averages of the flow field in the plane of the source and receiver. Thus, determinations of C and u carry immediate implications for the ocean circulation and must be consistent with known physics.
The forward problem has been presented in detail: Given C (or S) and u, and the characteristics of a sound source, compute the detailed structure of the signal as recorded at a receiver of known characteristics. This problem is labeled “forward” mainly as a reflection of its connection to the classic problem of finding solutions to the wave equation.
The “inverse” problem demands calculation of the ocean properties, C and/or u, given the measured properties of the arriving signal. At this stage, the problem becomes a matter of intense oceanographic interest.
Oceanographers are mostly familiar with point value data (e.g., a current meter reading or a thermometer measurement). In contrast, tomographic data are weighted integrals through the oceanic field.
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- Ocean Acoustic Tomography , pp. 222 - 302Publisher: Cambridge University PressPrint publication year: 1995
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