Laboratory Experiments on Sound Propagation in a Continuously Stratified Ocean Containing Internal Gravity Waves

date January 30, 2015
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Friday, January 30, 2015 4:00pm in ETC 4.150

Dr. Likun Zhang
Center for Nonlinear Dynamics
The University of Texas at Austin
http://chaos.utexas.edu/people/post-docs/likun-zhang

The speed of sound in the ocean varies with temperature, salinity, and pressure over the entire ocean depth. This variation results in a sound speed profile that supports a sound channel for transmitting information over great distances in the ocean. The transmission is strongly affected by local water column oscillations that result from gravity wave motions internal to the ocean. Internal gravity waves can propagate in any density-stratified fluid; in the oceans the increase of density with depth is due to decreasing temperature and increasing salinity. We present results from a laboratory tank experiment that models sound propagation in a stratified ocean containing internal gravity waves. The experiment determines (1) the refraction of acoustic wavefronts due to sound speed gradients and (2) sound speed fluctuations arising from the internal gravity waves. This research provides a data set for comparison with modeling of sound propagation in the oceans.