Refraction of Sound in a Horizontally Inhomogeneous, Time-Dependent Ocean
Refraction of Sound in a Horizontally Inhomogeneous, Time-Dependent Ocean
复制标题
声音在水平不均匀、随时间变化的海洋中的折射
DOI：
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发表时间：
2006
影响因子：
4.1
通讯作者：
V. Goncharov
中科院分区：
文献类型：
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作者：
O. Godin;V. Zavorotny;A. Voronovich;V. Goncharov
对海洋声速场的三维结构进行具有预测声场所需的空间和时间分辨率的测量，就实验资产而言是极其苛刻的，而且在实践中很少能得到。在这项研究中，在射线近似中开发了一种简单的分析技术，以量化声波传播时间和传播方向的不确定性，这些不确定性是由于对水平面上声速变化的不完全了解或纯粹的统计特征造成的。在确定性和随机介质中，考虑了由窄带源发射的声波频率由于环境参数的时间变化而发生的变化。在具有局部统计均匀的、随时间变化的声速三维波动的随机介质中，信号频率和方位角方差的计算以及由于水平折射引起的走时偏差的计算可以近似地简化为对背景、随距离变化的确定性介质中沿射线的环境波动的各自统计参数进行积分。该技术应用于沿海海洋的声传输，其中潮汐产生的非线性内波是声速波动的主要来源，而在深海中，波动主要是由于具有Garrett-Munk谱的空间漫射内波。讨论了深水和浅水中三维和四维声效应的意义
Measurements of the three-dimensional (3-D) structure of a sound-speed field in the ocean with the spatial and temporal resolution required for prediction of acoustic fields are extremely demanding in terms of experimental assets, and they are rarely available in practice. In this study, a simple analytic technique is developed within the ray approximation to quantify the uncertainty in acoustic travel time and propagation direction that results from an incomplete knowledge or purely statistical characterization of sound-speed variability in the horizontal plane. Variation of frequency of an acoustic wave emitted by a narrowband source due to a temporal variation of environmental parameters is considered for deterministic and random media. In a random medium with locally statistically homogeneous, time-dependent 3-D fluctuations of the sound speed, calculation of the signal frequency and bearing angle variances as well as the travel-time bias due to horizontal refraction is approximately reduced to integration of respective statistical parameters of the environmental fluctuations along a ray in a background, range-dependent, deterministic medium. The technique is applied to acoustic transmissions in a coastal ocean, where tidally generated nonlinear internal waves are the prevailing source of sound-speed fluctuations, and in a deep ocean, where the fluctuations are primarily due to spatially diffuse internal waves with the Garrett-Munk spectrum. The significance of 3-D and four-dimensional (4-D) acoustic effects in deep and shallow water is discussed