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Eric Thorsos

Sr. Principal Physicist--Retiree

Affiliate Associate Professor, Electrical Engineering

Email

eit@apl.washington.edu

Phone

206-543-1369

Research Interests

Shallow Water Acoustic Propagation, Sediment Acoustics, Rough Surface Scattering

Biosketch

Dr. Thorsos research addresses high-frequency sound penetration into, propagation within, and scattering from the shallow-water seafloor. One finding is that high-frequency acoustic penetration into sediments at grazing angles below the critical angle is possible--an important issue in detection of buried mines.

Dr. Thorsos is also presently leading a project to improve our understanding of the effects of sea surface and bottom roughness on shallow water propagation, and to determine the best approaches to modeling this propagation. A specialist in numerical studies of scattering theory and on the validity of scattering theory approximations, Dr. Thorsos publishes in the Journal of the Acoustical Society of America and the IEEE Journal of Oceanic Engineering.

Department Affiliation

Acoustics

Education

B.S. Physics, Harvey Mudd College, 1965

M.S. Engineering & Applied Science, University of California, Davis-Livermore, 1966

Ph.D. Theoretical Nuclear Physics, MIT, 1972

Publications

2000-present and while at APL-UW

Comparison of transport theory predictions with measurements of the decrease in shallow water reverberation level as the sea state increases

Thorsos, E., J. Yang, W.T. Elam, F.S. Henyey, F. Li, and J. Liu, "Comparison of transport theory predictions with measurements of the decrease in shallow water reverberation level as the sea state increases," Proc., Meetings on Acoustics, 19, 070024, doi:10.1121/1.4800711, 2013.

More Info

2 Jun 2013

Transport theory has been developed for modeling shallow water propagation and reverberation at mid frequencies (1-10 kHz) where forward scattering from a rough sea surface is taken into account in a computationally efficient manner. The method is based on a decomposition of the field in terms of unperturbed modes, and forward scattering at the sea surface leads to mode coupling that is treated with perturbation theory. Reverberation measurements made during ASIAEX in 2001 provide a useful test of transport theory predictions. Modeling indicates that the measured reverberation was dominated by bottom reverberation, and the reverberation level at 1 and 2 kHz was observed to decrease as the sea surface conditions increased from a low sea state to a higher sea state. This suggests that surface forward scattering was responsible for the change in reverberation level. By modeling the difference in reverberation as the sea state changes, the sensitivity to environmental conditions other than the sea surface roughness is much reduced. Transport theory predictions for the reverberation difference are found to be in good agreement with measurements.

Modelling shallow water propagation and reverberation using moment equations

Thorsos, E., "Modelling shallow water propagation and reverberation using moment equations," Proceedings, 11th European Conference on Underwater Acoustics, 2-6 July, Edinburgh, 1226-1233 (Institute of Acoustics, 2012).

2 Jul 2012

Synthetic aperture sonar imaging of simple finite targets

Kargl, S.G., K.L. Williams, and E.I. Thorsos, "Synthetic aperture sonar imaging of simple finite targets," IEEE J. Ocean. Eng., 37, 516-532, doi:10.1109/JOE.2012.2200815, 2012.

More Info

1 Jul 2012

During the Sediment Acoustics Experiment 2004 (SAX04), a synthetic aperture sonar (SAS) was used to detect simple targets that were either proud or buried below a water-sediment interface, where the nominal grazing angle of incidence from the SAS to the point above a buried target was well below the critical grazing angle. SAS images from other measurements below the critical angle have also produced target detections of buried spheres and finite cylinders. Models and numerical simulations are developed to investigate these proud and buried target detections. For buried targets, the simulations include estimates of reverberation from the rough seafloor, the subcritical penetration through the seafloor, scattering from a target, and propagation back to the SAS. For proud targets, the simulations include the scattering from the target where interaction with the seafloor is included through simple ray models. The simulations used environmental and material parameters measured during SAX04. The environmental measurements include profiles of small-scale surface roughness and superimposed ripple structure. The SAS simulations and model/measurement comparisons over a frequency range of 10-50 kHz further support scattering from sediment ripple structure as the dominant mechanism for subcritical penetration in this range.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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