南黄海海域海底中频（1-10kHz）反向散射特性与底质类型的关系研究

Acoustic bottom scattering is the main source of reverberation disturbance background in target detection and recognition near the bottom. Especially, the accurate estimation of bottom scattering strength is necessary for prediction of sonar performance under the reverberation disturbance background in shallow-water environment. This proposal concerns on the characteristics of bottom backscattering in the frequency range of 1-10kHz near the area of South Yellow Sea, which is obtained through a parametric array. Then the change rule follows with sediment types will be summarized. Meanwhile, the environment parameters in the experimental area will be measured as well, including the bottom topography, the geoacoustic parameters, the physical parameters, and so on. The main acoustic scattering mechanisms in the interested frequency band are considered. Subsequently, a bottom backscattering model on the basis of environment parameters are established, which is validated and improved through the comparison of the measured backscattering strength data with the predicted results of the model. The final purpose is accurately predicting the mid-frequency bottom backscattering strength of this area, which is valuable for military application.

海底声散射是对海底附近目标进行探测和识别时混响背景干扰的主要来源，特别是浅海混响背景干扰下的声呐性能预报离不开海底散射强度的准确估计。本项目拟采用参量阵获取1-10kHz频率范围内南黄海海域海底反向散射特性，并总结其随底质类型的变化规律。同时，对实验海域的环境参数进行测量，包括海底地形、海底地声参数和物理参数等。考虑研究频段内的主要声散射机制，建立基于环境参数的海底反向散射模型，通过比较测得的反向散射强度数据与模型预报结果对所建立的散射模型进行验证和完善，最终达到准确预报该海域海底中频反向散射强度的目的，具有重要的军事应用价值。

海底声散射是对海底附近目标进行探测和识别时混响背景干扰的主要来源，特别是浅海混响背景干扰下的声呐性能预报离不开海底散射强度的准确估计。本项目采用全向性的声源和水听器，在我国南黄海海域测量了6–24kHz频率范围内、掠射角20°–70°下的砂质和泥质海底的反向散射强度，并与建立的反向散射模型进行了比较和分析。对于砂质站位，反向散射强度随掠射角的增大而增大，大掠射角（60°–70°）下增大得更快。对于泥质站位，50°–70°掠射角范围内的反向散射强度随掠射角的增大而减小。从频率的角度来看，砂质站位的反向散射强度总体上随频率的增大而略微增大，而泥质站位的反向散射强度随频率的增大略有减小。Lambert定律与实验数据的拟合结果表明，大掠射角下的反向散射强度偏离Lambert定律。散射模型与实验数据的拟合结果表明，两个站位低频条件下（<10kHz）的主要散射机制为海底界面粗糙散射，而对于泥质站位，沉积物内部不均匀性引起的体积散射在高频大掠射角条件下起主导作用。此外，通过模型-数据拟合，对沉积物地球物理学参数（包括物理参数和地声参数）以及反映海底界面粗糙和沉积物内部不均匀性统计特征的参数进行了估计。与部分实测参数相比：砂质站位的孔隙度、粗糙度谱的谱指数、粗糙度谱的谱强度和平均颗粒粒度得到了较好的估计结果，相对误差分别为1.95%、8.99%、11.5%和9.77%，而泥质站位的孔隙度和平均颗粒粒度的相对误差则分别为8.50%和2.47%。相关研究可为海洋混响和海洋声场的精确预报提供重要参数，有助于提高我军声呐装备在抗混响方面的作战性能。