Acoustic scattering from double-diffusive microstructure
MetadataShow full item record
KeywordAcoustic measurement; Acoustic wave scattering; Echo; Oceanographic techniques; Pulse compression; Remote sensing; Underwater sound
Laboratory measurements of high-frequency broadband acoustic backscattering (200–600 kHz) from the diffusive regime of double-diffusive microstructure have been performed. This type of microstructure, which was characterized using direct microstructure and optical shadowgraph techniques, is identified by sharp density and sound speed interfaces separating well-mixed layers. Vertical acoustic backscattering measurements were performed for a range of physical parameters controlling the double-diffusive microstructure. The echoes have been analyzed in both the frequency domain, providing information on the spectral response of the scattering, and in the time domain, using pulse compression techniques. High levels of variability were observed, associated with interface oscillations and turbulent plumes, with many echoes showing significant spectral structure. Acoustic estimates of interface thickness (1–3 cm), obtained for the echoes with exactly two peaks in the compressed pulse output, were in good agreement with estimates based on direct microstructure and optical shadowgraph measurements. Predictions based on a one-dimensional weak-scattering model that includes the actual density and sound speed profiles agree reasonably with the measured scattering. A remote-sensing tool for mapping oceanic microstructure, such as high-frequency broadband acoustic scattering, could lead to a better understanding of the extent and evolution of double-diffusive layering, and to the importance of double diffusion to oceanic mixing.
Author Posting. © Acoustical Society of America, 2007. 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 122 (2007): 1449-1462, doi:10.1121/1.2764475.
Suggested CitationJournal of the Acoustical Society of America 122 (2007): 1449-1462
Showing items related by title, author, creator and subject.
Differences between sound scattering by weakly scattering spheres and finite-length cylinders with applications to sound scattering by zooplankton Stanton, Timothy K.; Wiebe, Peter H.; Chu, Dezhang (Acoustical Society of America, 1998-01)A modeling study was conducted to determine the conditions under which fluidlike zooplankton of the same volume but different shapes (spherical/cylindrical) have similar or dramatically different scattering properties. ...
A phase-compensated distorted wave Born approximation representation of the bistatic scattering by weakly scattering objects : application to zooplankton Chu, Dezhang; Ye, Zhen (Acoustical Society of America, 1999-10)The distorted wave Born approximation (DWBA) method has been successfully used in modeling the acoustic backscattering by weakly scattering zooplankton [Stanton et al., J. Acoust. Soc. Am. 94, 3463–3472 (1993), Wiebe et ...
Sound scattering by several zooplankton groups. I. Experimental determination of dominant scattering mechanisms Stanton, Timothy K.; Chu, Dezhang; Wiebe, Peter H.; Martin, Linda V.; Eastwood, Robert L. (Acoustical Society of America, 1998-01)The acoustic scattering properties of live individual zooplankton from several gross anatomical groups have been investigated. The groups involve (1) euphausiids (Meganyctiphanes norvegica) whose bodies behave acoustically ...