Down‐slope enhancement models for low‐frequency ocean noise and propagation
作者:
J. Northrop,
R. A. Wagstaff,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1978)
卷期:
Volume 64,
issue S1
页码: 46-46
ISSN:0001-4966
年代: 1978
DOI:10.1121/1.2004217
出版商: Acoustical Society of America
数据来源: AIP
摘要:
A simple model has been derived for down‐slope enhancement (DSE) of underwater sound (the so‐called "Megaphone effect"). The model predicts DSE for shallow source/deep receiver travel paths across a sloping bottom as the difference between semispherical spreading (15 logR) + αRand cylindrical spreading (10 logR) + αRplus a constantK. In this formulation the frequency dependent attenuation term (αR) is canceled out by the subtraction operation leaving the simple formula: DSE = (5 logR) −K. By comparing measured values of DSE with those computed using this formula, the value of the constantKwas found to be about 5 dB when the rangeRis expressed in nautical miles. DSE for sound crossing the sloping sides of seamounts was found to be about 5 dB higher than that for continental slopes. These models have been used to compute the effective low‐frequency source levels for shipping lanes crossing the continental slopes in areas where the horizontal directionality of ambient noise has been measured. [Work supported by LRAPP.]
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