Low‐frequency acoustic propagation loss in shallow water over hard‐rock seabeds covered by a thin layer of elastic–solid sediment
Low‐frequency acoustic propagation loss in shallow water over hard‐rock seabeds covered by a thin layer of elastic–solid sediment
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DOI：
10.1121/1.399951
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发表时间：
1990-07
影响因子：
2.4
通讯作者：
S. Hughes;D. Ellis;D. Chapman;P. Staal
中科院分区：
文献类型：
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作者：
S. Hughes;D. Ellis;D. Chapman;P. Staal
浅水海床往往是多样和复杂的，并且已知对声传播有很强的影响。其中一些海床可以成功地模拟为流体或固体半空间。然而，在几个粗糙、部分暴露的硬岩海床区域，测量到了这些模型的意外高传播损耗。结果表明，这些地区的高传播损耗可以通过在硬岩基底上引入一层薄的弹性固体沉积物来成功建模。使用Safari快场程序的传播损耗预测在规则间隔的频率处显示出高损耗的频带。简正模式计算显示共振现象，在这些相同的频率下，模式衰减系数出现大峰值，模式波数快速变化。海底反射损失计算表明，高的传播损失是由于剪切波在沉积层中的吸收。
Shallow‐water seabeds are often varied and complex, and are known to have a strong effect on acoustic propagation. Some of these seabeds can be modeled successfully as fluid or solid half‐spaces. However, unexpectedly high propagation loss with respect to these models has been measured in several regions with rough, partially exposed, hard‐rock seabeds. It is shown that the high propagation loss in these areas can be modeled successfully by introducing a thin layer of elastic–solid sediment over the hard‐rock substrate. Propagation loss predictions using the safari fast‐field program exhibit bands of high loss at regularly spaced frequencies. Normal‐mode calculations show resonance phenomena, with large peaks in the modal attenuation coefficients at these same frequencies, and with rapid changes in the mode wavenumbers. Bottom reflection loss calculations indicate that the high propagation loss is due to absorption of shear waves in the sediment layer.