Wave Propagation R & D Activities
Ocean Acoustic Tomography
Ocean acoustic travel-time tomography was introduced by Munk and Wunsch in 1979 as a remote-sensing technique for monitoring the spatial and temporal variability of oceanographic parameters (mainly temperature and currents) in the large scale. Measuring the travel times of pulsed acoustic signals propagating through the water mass over a multitude of different paths, and exploiting the knowledge about how travel times are affected by the ocean state, the latter can be obtained by inversion. Low-frequency sound propagates efficiently over long distances of thousands of kilometres and thus ocean acoustic tomography can be used to monitor large sea areas, from the mesoscale to the basin and global scale.
|Left: Evolution of average temperature profile along a 600-km section in the Western Mediterranean (from biweekly hydrographic surveys). Middle: Evolution of measured acoustic travel times along the section (tomographic data). Right: Evolution of retrieved temperature profiles by inversion of travel time data (tomographic results).|
IACM's Wave Propagation Group is active in the field of ocean acoustic tomography since the early 90's focusing on the development of enhanced analysis methods for tomographic data, based on wave-theoretic propagation modeling, with contributions in the following directions.
- Wave-theoretic modelling of tomographic observables
- Adaptive non-linear inversion methods
- Statistical identification and inversion schemes
- Automation of tomography data analysis
- Data analysis of large-scale tomography experiments
- Matched-field processing
There are collaborations with major oceanographic institutions developing and applying tomographic techniques for ocean observation in Europe and America, such as IfM Kiel (Leibniz institute), IFREMER (France), the Scripps Oceanographic Institution (US), and the University of Victoria (Canada).