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Eric Thorsos

Sr. Principal Physicist--Retiree

Affiliate Associate Professor, Electrical Engineering





Research Interests

Shallow Water Acoustic Propagation, Sediment Acoustics, Rough Surface Scattering


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



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


2000-present and while at APL-UW

Noise background levels and noise event tracking/characterization under the Arctic ice pack: Experiment, data analysis, and modeling

Williams, K.L., M.L. Boyd, A.G. Soloway, E.I. Thorsos, S.G. Kargl, and R.I. Odom, "Noise background levels and noise event tracking/characterization under the Arctic ice pack: Experiment, data analysis, and modeling," IEEE J. Ocean. Eng., 43, 145-159, doi:10.1109/JOE.2017.2677748, 2018.

More Info

1 Jan 2018

In March 2014, an Arctic Line Arrays System (ALAS) was deployed as part of an experiment in the Beaufort Sea (approximate location 72.323 N, 146.490 W). The water depth was greater than 3500 m. The background noise levels in the frequency range from 1 Hz to 25 kHz were measured. The goal was to have a three-dimensional sparse array that would allow determination of the direction of sound sources out to hundreds of kilometers and both direction and range of sound sources out to 1–2 km from the center of the array. ALAS started recording data at 02:12 on March 10, 2014 (UTC). It recorded data nearly continuously at a sample rate of 50 kHz until 11:04 on March 24, 2014. Background noise spectral levels are presented for low and high floe-drift conditions. Tracking/characterization results for ice-cracking events (with signatures typically in the 10–2000-Hz band), including the initiation of an open lead within about 400 m of the array, and one seismic event (with a signature in the 1–40-Hz band) are presented. Results from simple modeling indicate that the signature of a lead formation may be a combination of both previously hypothesized physics and enhanced emissions near the ice plate critical frequency (where the flexural wave speed equals that of the water sound speed). For the seismic event, the T-wave arrival time results indicate that a significant amount of energy coupled to T-wave energy somewhere along the path between the earthquake and ALAS.

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.

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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

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