Horizontal Lloyd mirror patterns from straight and curved nonlinear internal waves
McMahon, Kara G.
Reilly-Raska, L. K.
Siegmann, William L.
Lynch, James F.
Duda, Timothy F.
MetadataShow full item record
Experimental observations and theoretical studies show that nonlinear internal waves occur widely in shallow water and cause acoustic propagation effects including ducting and mode coupling. Horizontal ducting results when acoustic modes travel between internal wave fronts that form waveguide boundaries. For small grazing angles between a mode trajectory and a front, an interference pattern may arise that is a horizontal Lloyd mirror pattern. An analytic description for this feature is provided along with comparisons between results from the formulated model predicting a horizontal Lloyd mirror pattern and an adiabatic mode parabolic equation. Different waveguide models are considered, including boxcar and jump sound speed profiles where change in sound speed is assumed 12 m/s. Modifications to the model are made to include multiple and moving fronts. The focus of this analysis is on different front locations relative to the source as well as on the number of fronts and their curvatures and speeds. Curvature influences mode incidence angles and thereby changes the interference patterns. For sources oriented so that the front appears concave, the areas with interference patterns shrink as curvature increases, while convexly oriented fronts cause patterns to expand.
Author Posting. © Acoustical Society of America, 2012. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 131 (2012): 1689-1700, doi:10.1121/1.3666004.
Showing items related by title, author, creator and subject.
Badiey, Mohsen; Katsnelson, Boris G.; Lin, Ying-Tsong; Lynch, James F. (Acoustical Society of America, 2011-03-28)Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet ...
Frank, Scott D.; Badiey, Mohsen; Lynch, James F.; Siegmann, William L. (Acoustical Society of America, 2004-12)To investigate acoustic effects of nonlinear internal waves, the two southwest tracks of the SWARM 95 experiment are considered. An airgun source produced broadband acoustic signals while a packet of large nonlinear internal ...
Experimental evidence of three-dimensional acoustic propagation caused by nonlinear internal waves Frank, Scott D.; Badiey, Mohsen; Lynch, James F.; Siegmann, William L. (Acoustical Society of America, 2005-08)The 1995 SWARM experiment collected high quality environmental and acoustic data. One goal was to investigate nonlinear internal wave effects on acoustic signals. This study continues an investigation of broadband airgun ...