Acoustic variability due to layered finestructure in the Arctic
作者:
M. Schulkin,
G. R. Garrison,
T. Wen,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1978)
卷期:
Volume 64,
issue S1
页码: 22-22
ISSN:0001-4966
年代: 1978
DOI:10.1121/1.2004103
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Acoustic transmission measurements, in the frequency range 10–60 kHz, have been carried out in the presence of layered, thermal fine structure under arctic ice. The term “layered fine structure” refers to relatively stable, slowly changing thermal layers in the ocean that have a vertical scale of about a meter to several meters. Their horizontal extent may be 10–100 times larger. In these measurements, acoustic transmission is strongly affected by the presence, near the transmitter, of a layer or layers with a sound speed maximum. In the literature these warm layers are sometimes called “antiwaveguide” or “barrier” layers. Three types of space‐time variability have been found in the received intensity versus depth records: (1) A small random variability observed at relatively steep transmission angles, (2) a frequency‐independent variability which can be related to convergence/divergence of rays in the refraction field of the layer, and (3) a frequency‐dependent variability which seems to arise from the interference between direct rays and those sharply refracted by the layer. A spectral analysis of the interference region confirms that the spatial wavelength in depth is inversely proportional to the acoustic frequency. [Work supported by Arctic Submarine Laboratory of the Naval Ocean Systems Center, San Diego, CA.]
点击下载:
PDF
(148KB)
返 回