琼东上升流锋面对声传播影响的研究

As important mesoscale phenomena in the ocean environment, ocean fronts have been considered to be one of the main contributions of spatial variation in the actual ocean environment. They directly influence the structure of sound velocity profile, and further make an impact on sound propagation. Ocean fronts often occur in the continental shelf of the China Seas. The research of sound propagation in the ocean environment with ocean fronts and typical results obtained play important theoretical and practical roles in improving the detecting performance of underwater equipment. . The sound propagation experiment and sectional observation of temperature, salt and sound velocity will be conducted in Qiongdong upwelling frontal zone in this project. Based on the spatial distribution characteristics of upwelling frontal, the model of upwelling frontal sound velocity will be constructed. The observed data and frontal sound velocity model will be combined to calculate sound field. A comparison of model results and data will be made to explore the influence of upwelling frontal on sound propagation.

海洋锋是海洋环境中重要的中尺度现象，是引起实际海洋环境空间分布变化的主要因素之一，它直接影响到声速剖面结构特征，并进一步影响海区的声传播特性。在中国近海大陆架及周边海域常有海洋锋出现，研究有关的声传播特性，总结其中的声传播典型规律，对提高水声设备的探测性能具有重要的理论意义和实际应用价值。. 本项目拟开展琼东上升流锋面处温、盐和声速的断面观测及声传播实验，获取该海域的上升流锋面分布特征，建立锋面声速模型。利用观测数据和锋面声速模型，结合二维PE模型进行有关的声场计算，并与声传播实验数据比对验证，探究上升流锋面对声传播的影响。

本项目开展了上升流锋面处温、盐和声速的断面观测及声传播实验，利用Munk模型、简化的Wilson公式计算水下声速，并且分别用黑潮区声速锋面模式以及海洋锋二维模型建立了海洋锋区声速计算模式，利用观测数据和锋面声速模型，结合二维PE模型进行有关的声场计算，并与声传播实验数据比对验证。通过计算得到以下结论：声线在进入锋区后，与进入前相比有明显的偏转；无论海洋锋是否存在，传播损失的变化量都与频率有关，若声源的频率越高，其传播损失就会越大；若存在海洋锋，则在经过海洋锋区后，声波的传播损失会增大，且频率越大，其传播损失的变化量也会增加。