Accession Number : AD1011438


Title :   Deep Water Acoustics


Descriptive Note : Technical Report,01 Jan 2013,31 Mar 2016


Corporate Author : University of Washington - Applied Physics Laboratory Seattle United States


Personal Author(s) : Mercer,James A ; White,Andrew


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1011438.pdf


Report Date : 28 Jun 2016


Pagination or Media Count : 31


Abstract : A mechanism is presented by which the observed acoustic intensity is made to vary due to changes in the acoustic path that are caused by internal-tide vertical fluid displacements. The position in range and depth of large-scale caustic structure is determined by the background sound-speed profile. Internal tides cause a deformation of the background profile, which changes the positions of the caustic structuresintroducing slow intensity changes at a fixed position in depth and range. Parabolic equation and Hamiltonian ray-tracing calculations indicate that internal tides could cause enhanced variability in the intensity in the form of slow changes. Furthermore, the calculations demonstrate how large-scale perturbations to the index of refraction can result in intensity fluctuations--contrary to conclusions of previous theoretical work.


Descriptors :   Deep depth under water acoustics , ray tracing , acoustic measurement , ambient noise , internal waves , Philippine Sea , intensity , tides , Acoustic scattering , models


Distribution Statement : APPROVED FOR PUBLIC RELEASE