利用时域波形快速反演海底单参数的方法

A rapid inversion scheme for seabed single parameter using time-domain impulse response

海底单参数反演由于反演维数少,较之多维反演具有实施简单快捷的优点.首先定义小掠射角下反射损失随掠射角变化率FdB为单个参数描述海底性质,构建单参数反演模型;其次,从简正波与射线理论出发,对时域脉冲波形与海底反射性质之间的关系进行了推导,并讨论衰减机制;最后,基于该关系设计出利用最小二乘法对时域波形进行反演的方法.对北黄海实验数据进行了实际反演,通过海底采样验证反演结果对海底性质估计的正确性,同时基于反演结果的传播损失预报值与实测值符合良好.该方法实施仅需要单个水听器,待测物理量少,所获结果较为可靠,且能满足大多数应用的需要.

Compared with multi-dimension inversion, the single parameter inversion has the main advantages that inversion complexity decreases with the number of parameters increasing. Firstly, the slop of bottom loss versus grazing angle FdB is proposed to serve as a single parameter. Secondly, in terms of mode and ray paths, the relation between impulse response and seabed reflection loss property FdB is discussed. Finally, a time-domain inversion method using least-squares fitting to intensity decay rate is designed accordingly. Experimental data in North Yellow Sea are inverted. The inverted results are evaluated by the core samples. Good agreement is also obtained between measurement and predictions of transmission losses with using the inverted result. As this method only requires single hydrophone and comparatively few measurements, it is believed to provide a rapid but robust estimation of FdB which can meet the need for many applications.