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中文核心期刊

海洋锋对海洋环境噪声场垂直空间特性的影响

The influence of ocean fronts on the vertical spatial characteristics of ambient noise

  • 摘要: 海洋锋特殊的声速结构会显著影响海洋环境噪声垂直空间特性。基于西北太平洋的实测海洋锋数据, 利用射线理论建立了三维海洋环境噪声场模型, 数值仿真分析了海洋锋环境下的噪声场垂直空间特性。结果表明, 在临界深度以上, 海洋锋使得噪声垂直指向性水平凹槽宽度减小、凹槽深度变浅, 噪声垂直相关性随阵元间距的增加先后向正相关、负相关再正相关方向发生更大偏移。海洋锋引起声道轴深度的变化会改变声线的到达俯仰角, 使部分不与海面海底接触的折射型声线转变为仅与海面接触的海面反射(RSR)型声线, 即有更多海面噪声源对接收点有能量贡献, 从而使得噪声垂直指向性水平凹槽宽度减小、凹槽深度变浅。对不同到达声线进一步分析表明, RSR型声线和海面海底反射型声线分别影响了噪声垂直相关函数的振荡幅值和振荡周期; RSR型声线的增加是引起噪声垂直相关性变化的主要原因。

     

    Abstract: The unique sound speed structures of ocean fronts have a significant influence on the vertical spatial characteristics of ocean ambient noise. This study establishes a three-dimensional ocean ambient noise field model using ray theory, based on in-situ ocean front data from the Northwest Pacific. Numerical simulations are performed to analyze the vertical spatial properties of the noise field under ocean front conditions. The results show that above the critical depth, ocean fronts reduce both the horizontal notch width and notch depth in the vertical directivity of noise. As hydrophone array element spacing increases, the vertical noise coherence undergoes a pronounced shift, transitioning sequentially from positive to negative correlation and back to positive correlation. Numerical analysis reveals that changes in the depth of the sound channel axis induced by ocean fronts modify the arrival elevation angles of acoustic rays. Specifically, a subset of refracted-refracted rays is converted into refracted-surface-reflected (RSR) rays, thereby increasing the energy contribution from sea-surface noise sources to the receiver. This conversion process explains the observed reductions in notch width and depth. Further analysis of acoustic ray paths demonstrates that RSR rays primarily modulate the oscillation amplitude of the vertical correlation function. Surface-reflected-bottom-reflected rays govern the oscillation period of the vertical correlation function. The enhanced prevalence of RSR rays is the main reason for the changes in noise vertical coherence.

     

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