深海三维海底山地形对甚低频声场的影响

Effect of three-dimensional seamount topography on very low frequency sound field in deep water

复杂海域海底地形的变化对海洋声传播有着重要影响,研究海底山和弹性海底共同作用下的声传播特性可以为水声技术提供理论基础。本文利用三维谱元法进行声传播数值模拟,从多途结构、界面波传播特性、三维效应等方面分析了该复杂海洋环境下的甚低频声场特性。仿真结果表明:海底山地形变化会引起传播过程中声信号的耦合转化从而激发深海海底界面波;影区内海底界面波相对能量最强,随着与界面距离的增加,界面波幅度呈指数衰减,而其他途径信号在一个波长内幅度几乎不变;海底山环境下的声传播会产生复杂的三维水平折射与散射现象,随着接收深度的增加地形变化引起的水平多途会逐渐增加。

To establish a theoretical basis for the use of underwater acoustic technology in complex sea areas under the combined effects of a seamount and an elastic seabed,in this paper,we use the three-dimensional spectral element method to perform a numerical simulation of the acoustic propagation.The spatial and temporal distributions of very low frequency sound fields in complex marine environments are analyzed with respect to the multipath structure,interface wave propagation characteristics,and three-dimensional effects.The results show that changes in the topography of a seamount causes the coupled transformation of sound signals as they propagate,which stimulates deep seabed interfacial waves.We analyze the relative energy distribution in the shadow region and the waveform changes near the interface using the receiving signal from the vertical receiving point behind the seamount.Finally,we compare the sound field in the vertical plane at a 20°angle from the symmetrical plane of the seamount with the results obtained in the two-dimensional model simulation and analyze the three-dimensional effect caused by the change in the seamount topography.