Applied Physics Laboratory and Department of Mechanical Engineering, University of Washington, 1013 NE 40th Street, Seattle, Washington 98105, USA.
J Acoust Soc Am. 2010 Jan;127(1):96-103. doi: 10.1121/1.3268594.
Measurements and modeling of spatial coherence and related angular spreading associated with forward scattering from the sea surface are presented. The measurements were taken in waters 80 m deep off the New Jersey coast in August 2006. Acoustic signals from a source at depth 40 m were recorded on a vertical line array of length 1.4 m, centered at depth 25 m, and at range 200 m. Measurements in the 14-20-kHz frequency range are reported; the rms waveheight H was 0.16 m, setting kH as approximately 10 where k is acoustic wavenumber. A systematic study of measurements taken over four source-receiver bearing angles separated by 90 degrees suggests a null influence of changing bearing angle or equivalently directional wave effects. Sound speed was characterized by a downward-refracting profile. Refraction modifies the vertical angular spread due to rough sea surface scattering, which can be understood from Snell's law. The Snell mapping is smooth, so an approximation based on the mean grazing angle provides a functional relation between the angular variance near the surface and that at the receiver. The latter is measurably reduced owing to refraction, the effect called angular compression, and a parameter that quantifies this effect is defined.
本文介绍了海面正向散射引起的空间相干性及其相关角扩展的测量和建模。测量是在 2006 年 8 月新泽西州海岸 80 米深的水域进行的。深度为 40 米的声源发出的声信号被记录在一个长 1.4 米、中心深度为 25 米、距离为 200 米的垂直线列阵上。报告了 14-20 kHz 频率范围内的测量结果；均方根波高 H 为 0.16 m，其中 kH 约为 10，其中 k 是声波数。对在四个声源-接收器方位角之间间隔 90 度进行的测量进行的系统研究表明，改变方位角或等效的方向波效应没有影响。声速由向下折射的轮廓来描述。折射改变了由于海面粗糙散射引起的垂直角扩展，可以根据斯奈尔定律来理解。斯奈尔映射是平滑的，因此基于平均掠射角的近似提供了表面附近的角度方差与接收器处的角度方差之间的函数关系。由于折射，这种效应称为角度压缩，后者可测量地减小了角度压缩，并且定义了量化此效应的参数。
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