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中文核心期刊

北极冰层覆盖下气枪声源双基地混响平均强度

The average intensity of bistatic reverberation from air-gun beneath Arctic ice cover

  • 摘要: 为提高极地冰区有源声呐探测性能, 研究了北极冰层覆盖下的双基地混响平均强度衰减特性。首先将冰层建模为具有粗糙下界面的弹性介质, 数值计算了海水–弹性冰层粗糙界面的相干反射系数、散射强度, 并利用经验散射函数描述海底散射特性, 结合椭圆环状划分方法确定双基地混响散射区域, 建立了冰层覆盖下的双基地海洋混响模型。研究结果表明: 在掠射角0°~70°范围内, 冰下散射强度明显高于平均风速为5 m/s时的海面散射强度; 冰层参数及发射信号频率主要通过影响冰下散射强度引起冰下混响强度变化, 其中横波声速、冰层厚度、冰下粗糙界面的均方根起伏高度、入射声波频率对冰下混响强度及衰减趋势影响最大; 随冰下粗糙界面的均方根起伏高度、入射声波频率增加, 冰下反射损失增大, 海底混响强度随时间衰减的速度增大。最后, 利用北极气枪声源混响数据验证了模型的有效性。

     

    Abstract: To improve the performance of active sonar detection in polar ice-covered regions, the attenuation characteristics of the average bistatic reverberation intensity under Arctic ice cover are investigated. The ice layer is first modeled as an elastic medium with a rough lower interface, and the coherent reflection coefficient and scattering intensity of the seawater-elastic ice layer rough interface are numerically calculated. The seabed scattering characteristics are described by an empirical scattering function. The bistatic scattering region of the underwater reverberation is determined using the elliptical ring partitioning method, leading to the establishment of a bistatic marine reverberation model under the ice layer. The results show that the scattering intensity beneath the ice is significantly higher than the surface scattering intensity within the grazing angle range of 0°−70° at an average wind speed of 5 m/s. The ice layer parameters and the transmitted signal frequency mainly affect the scattering intensity beneath the ice, thereby causing variations in the underwater reverberation intensity. Among these, the shear wavespeed, ice layer thickness, root-mean-square roughness height of the lower ice interface, and incident sound wave frequency have the greatest influence on the underwater reverberation intensity and attenuation trend. As the root-mean-square roughness height of the lower ice interface and the incident sound wave frequency increase, the reflection loss beneath the ice increases, and the seabed reverberation intensity decays more rapidly with time. Finally, the effectiveness of the model is validated using reverberation data from an Arctic air-gun source.

     

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