浅海温跃层声散射实验研究

Sound scattering experiment of thermocline in shallow sea

本文给出１９８８、１９８９和１９９２年夏季南黄海海域三站位（水深３４米、４４米和３９米）处的温跃层声脉冲反向散射实验结果。实验用窄带脉冲声源的中心频率分别为１２０ｋＨｚ、１６０ｋＨｚ和２００ｋＨｚ。实验过程中同时用ＣＴＤ仪昼夜分段记录温、盐、深参数和分层拖网采集浮游生物样本。作者根据Ｒ．Ｋｉｎｄ关于平面波在任意分布不均匀层系上反射系数谱的计算方法，求出以实测温、盐垂直分布构成的不均匀层系上反射系数谱，得到跃层散射在时域上的数值模拟散射信号，与海上实测记录在时域和幅度进行对比。三年同期重复实验结果表明：实测跃层散射波到达接收点的时间与按温度剖面所做数值模拟计算结果相符。浮游生物样品分析数据与声信号记录看不出确定的对应关系，说明声散射主要是海水介质的物理不均匀性引起。

This article presents the result of sound scattering experiments of thermocline, which were done at three stations in Southern Yellow Sea of China. The center frequencies of sources used in these experiments are 120 kHz, 160 kHz and 200 kHz respectively. During the process of experiments, the CTD was used to record the temperature and salinity of different depth, while plankton were sampling layerly. According to R. KIND's method, we calculate the reflection coefficient spetrum of nonuniform layered system to get the scattering signals by digital simulation for comparition with those from the experiments. The results of experiments showed that the reaching time of seatering signals matched the time obtained by digital simulation. On ther other hand, the relation between the density distribution of the plankton around the thermocline and the reaching time of the scattering signals was not definite enough. So it can be concluded that the major mechanism of sound scattering is due to the nonuniformity of tempaerature in the sea.