Attenuation measurement with sonobuoys
作者:
Robert D. Stoll,
Robert E. Houtz,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1983)
卷期:
Volume 73,
issue 1
页码: 163-172
ISSN:0001-4966
年代: 1983
DOI:10.1121/1.388834
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Sonobuoy data in a number of shelf areas have yielded travel time curves which are relatively smooth and which result in velocity–depth profiles that are nearly straight lines to depths of several kilometers. Moreover, many of the records contain several multiples of the first refracted arrival which are well separated from the first arrival and free of excessive noise. Such data are ideal for comparing the amplitude of the first arrival and the amplitude at the corresponding point on the multiple at double distance and double time. By taking the ratio of these amplitudes, the effects of geometrical spreading and the angular dependence of the source are removed so that estimates of total attenuation as a function of depth and frequency are much more easily studied. In this paper we present an example of such a study using sonobuoy data from the Sarawak basin which is located in the South China Sea (4 °N–110 °E). Measurements made in the frequency range of 10 to 60 Hz suggest that the logarithmic decrement δ or the quality factorQare not constants but depend rather strongly on frequency in the diving waves that were studied.
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