Applied Physics Laboratory and Mechanical Engineering, University of Washington, 1013 NE 40th Street Seattle, Washington 98105, USA.
J Acoust Soc Am. 2013 Sep;134(3):1843-53. doi: 10.1121/1.4817846.
Results of an experiment to measure vertical spatial coherence from acoustic paths interacting once with the sea surface but at perpendicular azimuth angles are presented. The measurements were part of the Shallow Water 2006 program that took place off the coast of New Jersey in August 2006. An acoustic source, frequency range 6-20 kHz, was deployed at depth 40 m, and signals were recorded on a 1.4 m long vertical line array centered at depth 25 m and positioned at range 200 m. The vertical array consisted of four omni-directional hydrophones and vertical coherences were computed between pairs of these hydrophones. Measurements were made over four source-receiver bearing angles separated by 90°, during which sea surface conditions remained stable and characterized by a root-mean-square wave height of 0.17 m and a mixture of swell and wind waves. Vertical coherences show a statistically significant difference depending on source-receiver bearing when the acoustic frequency is less than about 12 kHz, with results tending to fade at higher frequencies. This paper presents field observations and comparisons of these observations with two modeling approaches, one based on bistatic forward scattering and the other on a rough surface parabolic wave equation utilizing synthetic sea surfaces.
呈现了一项实验的结果，该实验旨在测量与海面仅一次相互作用但在垂直方位角上相互垂直的声路径的垂直空间相干性。这些测量是 2006 年 8 月在新泽西海岸进行的浅水 2006 计划的一部分。一个频率范围为 6-20 kHz 的声源部署在深度为 40 m 的位置，信号由一个位于深度 25 m 处并位于 200 m 范围内的 1.4 m 长垂直线阵记录。垂直阵由四个全向水听器组成，在这些水听器之间计算了垂直相干性。在四个声源-接收器方位角之间进行了测量，这些方位角之间相隔 90°，在此期间，海面条件保持稳定，其均方根波高为 0.17 m，且由涌浪和风浪混合而成。当声频率小于约 12 kHz 时，根据声源-接收器方位，垂直相干性存在具有统计学意义的差异，结果在较高频率时趋于消失。本文介绍了现场观测结果，并将这些观测结果与两种建模方法进行了比较，一种方法基于双基地前向散射，另一种方法基于利用合成海面的粗糙表面抛物型波动方程。
