陆架斜坡海域内孤立波引起的声场起伏及基阵处理增益研究

The isolated internal waves (ISW) are widespread in the areas near the continental shelf, continental slope and island chain. The northeast of south China sea is one of the high incidence areas of ISW. The environment parameters are fluctuant in the presence of ISW, and the acoustic propagation characteristics will be abnormal, including the aberrant transmission loss and attenuation of acoustic field correlation. The heterogeneous waveguide caused by ISW lead detection performance of sonar system to decreased. In the continental slope area, ISW and sound waves propagating in the sea are greatly affected by the sloping bottom, and the waveguide is more complex than those in the shallow water and deep sea which has significant influence on the performance of sonar. However, the research on these issues is scarce, especially those related with the performance of array signal processing. Resorting to acoustic-internal wave joint experiment at a continental slope in the south China sea in the summer of 2019, this project will conduct studies on the acoustic field fluctuation and array gain caused by ISW in the continental slope area. The project is carried out in the following aspects: 1) the acoustic propagation properties affected by the fluctuant environmental parameters, and their dependence on the parameters of ISW; 2) the quantitative description of the acoustic field fluctuation, including the spatial correlation of sound field and the fluctuant transmission loss; 3) the array gain in the fluctuant waveguide and the correlation with the parameters of sound velocity profile /topography/source. The project will provide an insight on the acoustic field structure of continental slope area in the presence of ISW, explore the mechanism of array gain influence by the fluctuant waveguide. Finally, a preliminary cognition of the correlation among physical ocean, acoustic propagation and array gain in this area was formed, which can give a significant reference to improve the detection performance of sonar system.

内孤立波广泛存在于大陆架、大陆坡、岛链等附近海域，我国南海东北部是内孤立波高发区之一。内孤立波导致水文参数起伏，水声传播特性发生变化，包括传播损失异常和声场相关性衰减，最终导致声呐探测性能下降。陆架斜坡海域海底地形变化，在该海域传播的内孤立波和声波受海底影响较大，波导环境更加复杂，但相关研究非常缺乏。本项目依托2019年夏季南海东北部海域内波-声学联合观测实验，开展陆架斜坡海域内孤立波引起的声场起伏及基阵处理增益研究，具体包括内孤立波振幅/波形/位置等参数对该海域声场空间相关性和传播损失的影响，声场起伏特性定量描述，基阵处理增益变化规律及其与水文/地形/声源等参数的关系。初步了解和掌握内孤立波存在时陆架斜坡海域水下声场结构，探究起伏波导环境对基阵处理增益影响机理，形成针对该海域物理海洋、水声传播和基阵处理增益三者之间内在关联的初步认知，为提高声呐系统在该类型海域的探测性能提供依据。

内孤立波广泛存在于大陆架、大陆坡、岛链等附近海域，我国南海北部海域是全球内孤立波高发区之一。内孤立波导致海水内部水文参数起伏，水声传播特性也将随之发生变化，包括声传播损失异常、声场干涉结构变化和声场相关性衰减等，最终导致声呐探测性能下降。陆架斜坡海域海底地形变化，在该海域传播的内孤立波和声波受海底的影响均较大，波导环境更加复杂，但相关研究非常缺乏。本研究依托2014年南海西南大陆坡海域水下目标探测实验和2019年夏季南海北部海域内波-声学联合观测实验，开展陆架斜坡海域内孤立波引起的声场起伏及基阵处理增益研究，具体包括内孤立波对该海域声传播规律的影响机理，声场空间相关性衰减和传播损失起伏变化规律，基阵处理增益变化规律及其与水文/声源等参数的关系。初步了解和掌握内孤立波存在时陆架斜坡海域水下声场结构，探究复杂波导环境对基阵处理增益影响机理，形成针对该海域物理海洋、水声传播和基阵处理增益三者之间内在关联的初步认知，为提高声呐系统在该类型海域的探测性能提供依据。