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dc.contributor.authorSmith, W.J.
dc.dateFeb 1972
dc.date.accessioned2015-01-13T21:50:32Z
dc.date.available2015-01-13T21:50:32Z
dc.date.issued1972-02
dc.identifier.urihttps://hdl.handle.net/10945/44307
dc.description.abstractSixty Khz CW sound was propagated parallel to and near the ocean surface adjacent to an array of four thermistors, a salinometer, a sound velocimeter, a turbulent velocity probe, and a wave-height probe in order to investigate the statistics and environmental causes of amplitude modulation. The temporal variations of the sound amplitude modulation were studied during four twenty-minute runs over a range of 2 meters at varying depths from near the surface to 14 meters during sea-state one conditions in water of 16 meters-depth. Analysis indicated mean percentage amplitude modulation of approximately 5% with a variance of approximately 10 raised to the -3 power. Temporal correlation times were about 2 seconds except for a 7 second time near the bottom. The power spectral densities of the modulation show strong components corresponding to the predominant ocean wave frequencies as well as higher frequencies that may be attributed to bubble, temperature and/or salinity inhomogeneities. There is evidence that the microstructure dimensions are larger near the bottom than in the upper and middle depths.en_US
dc.description.sponsorshipThis task was supported by Naval Ship Systems Command and Office of Naval Research.en_US
dc.publisherMonterey, California: Naval Postgraduate School.en_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.en_US
dc.titleAmplitude Modulation of an Acoustic Wave Propagating Near the Sea Surfaceen_US
dc.typeTechnical Reporten_US
dc.contributor.departmentPhysics
dc.subject.authorAcoustic Amplitude Modulationen_US
dc.subject.authorOcean Acousticsen_US
dc.subject.authorBubblesen_US
dc.subject.authorNear surface Phenomenaen_US
dc.subject.authorOceanic Particle Velocityen_US
dc.identifier.npsreportNPS-61Md72021A
dc.description.distributionstatementApproved for public release; distribution is unlimited.


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