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海底地形变化对声传播具有重要影响.针对在南海深海区域海底斜坡环境下进行的一次声传播实验中观测到的一些不同于平坦海底的声传播现象,利用射线声学方法分析并解释了海底地形变化引起声传播差异的原因.结果表明,当声源深度位于131 m处时,在第一影区内,海底斜坡前较小幅度的海底山丘(凸起高度小于1/10海深),对第一次与海底作用而入射到该小海底山丘处的小掠射角(绝对值在10°–20°范围内)声波有反射遮挡作用,导致在其反射区特定传播距离上出现影响深度可达海面以下1300 m的倒三角声影区,比平坦海底环境下相同影区位置处的传播损失增大约8 dB.在第一会聚区内,海底斜坡对声波的反射阻挡作用使得从海面反射及水体向下折射的小掠射角(绝对值小于10°)声波所形成的会聚区结构消失,只保留从水体向上折射的会聚结构.因此,准确的海底地形对深海声传播预报及目标探测等应用非常重要.
The variation of the seafloor topography has an important influence on the sound transmission.Aiming at the acoustic propagation phenomena different from the flat seafloor observed in an acoustic propagation experiment under the seafloor slope in the deep sea area of the South China Sea, the radiation acoustics method is used to analyze and explain the seafloor topographic changes The results show that when the sound source depth is at 131 m, in the first shadow zone, there is a small amplitude of the seabed hills before the slope (the height of the bump is less than 1/10 sea depth) The first glittering angle (absolute value between 10 ° and 20 °) incident on the small ocean floor at the bottom of the seafloor is reflected obscuring the sound waves, resulting in the influence of the specific propagation distance on the reflecting area Up to about 1300 m below the sea surface of the inverted triangle sound shadow zone, than in the same submarine environment at the same shadow location of the propagation loss increase of about 8 dB In the first convergence zone, the submarine slope of the sound wave reflection barrier makes reflection from the sea And the small glancing angle (less than 10 ° in absolute value) refracted by the water body disappears, leaving only the convergent structure refracted upward from the water body. Therefore, Dissemination of forecasts and target detection applications is very important.