Average echoes from randomly oriented randomlength finite cylinders : zooplankton models
Date
199312Author
Stanton, Timothy K.
Chu, Dezhang
Wiebe, Peter H.
Clay, Clarence S.
Metadata
Show full item recordCitable URI
http://hdl.handle.net/1912/2511As published
http://dx.doi.org/10.1121/1.407200DOI
10.1121/1.407200Keyword
Underwater soundAbstract
By heuristically extending the previously developed ray solution [Stanton et al. J. Acoust. Soc. Am. 94, 3454–3462 (1993)] to predict the scattering by cylinders over all angles of incidence, approximate expressions are derived which describe the echo energy due to sound scattered by finite cylinders averaged over orientation and length. Both straight and bent finite length cylinders of high aspect ratio are considered over the full range of frequencies (Rayleigh through geometric scattering). The results show that for a sufficiently broad range of orientation, the average echo is largely independent of the degree of bend—that is, the results are essentially the same for both the straight and bent cylinders of various radii of curvature (provided the bend is not too great). Also, in the limit of high frequency (i.e., the acoustic wavelength is much smaller than the crosssectional radius of the object), the averages are independent of frequency. The resultant formulas derived herein are useful in describing the scattering by elongated zooplankton whose shape may not necessarily be known in the natural ocean environment. The average echo is shown to depend directly upon standard deviation (s.d.) of the angle of orientation as well as size. If independent measurements of size are made (such as from trawling samples), then the properties of the angle distribution and hence behavior may be inferred from the data. Averages over both angle and a narrow distribution of size are shown to only partially smooth out deep nulls in the scatter versus frequency curves. The formulas compare favorably with laboratory data involving aggregations of animals and a broad range of frequencies (38 kHz to 1.2 MHz).
Description
Author Posting. © Acoustical Society of America, 1993. 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 94 (1993): 34633472, doi:10.1121/1.407200.
Collections
Related items
Showing items related by title, author, creator and subject.

On the maximum observed wind speed in a randomly sampled hurricane
Solow, Andrew R. (American Meteorological Society, 20100301)There is considerable interest in detecting a longterm trend in hurricane intensity possibly related to largescale ocean warming. This effort is complicated by the paucity of wind speed measurements for hurricanes occurring ... 
Response of a pendulum spar to 2dimensional random waves and a uniform current
Rodenbusch, George (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 197808)A linearized theory for the response of a circular pendulum spar in 2dimensional waves and a uniform current is developed. The linear forces on the cylinder are predicted using an approximate potential flow theory for ... 
The development and application of random matrix theory in adaptive signal processing in the sample deficient regime
Pajovic, Milutin (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 201409)This thesis studies the problems associated with adaptive signal processing in the sample deficient regime using random matrix theory. The scenarios in which the sample deficient regime arises include, among others, the ...