海洋激光雷达漫射衰减系数反演方法研究

Research on inversion method of diffuse attenuation coefficient of ocean LiDAR

为了解决漫射衰减系数K d的反演依赖于原位测量数据的问题,提出了一种基于Klett和Fernald法反演K d的融合算法。该融合算法以Klett法反演结果为基准,计算出激光雷达比作为Fernald法迭代时的先验信息,再用Fernald法反演出更加精确的水体漫射衰减系数K d;并运用数学解析模型作为融合算法的仿真数据源,解决了实测信号数据量不足的问题,最后基于自研的双频激光雷达系统,利用海试数据对融合算法进行了实验验证。结果表明,融合算法反演得到K d值的均方根误差值为0.74 m-1,精度优于传统的Klett法和Fernald法;所提出的融合算法能够满足近岸浅海水体漫射衰减系数K d反演的收敛和精度要求,且能在没有原位现场环境先验信息的条件下快速计算激光雷达比。该研究对浅海水域的深度测量以及海洋剖面光学参数的测量是有帮助的。

In order to solve the problem that the inversion of the diffusion attenuation coefficient K d relies on in-situ measurement data,a fusion algorithm based on Klett and Fernald algorithm was proposed in order to inverse K d.The fusion algorithm was based on the inversion results of the Klett algorithm and calculated the light detection and ranging(LiDAR)ratio as prior information for the Fernald algorithm.Furthermore,the Fernald method was used to inverse the more accurate diffusion attenuation coefficient K d.In order to solve the problem of insufficient measured signal data,a mathematical analytic model was used as the simulation data source of the fusion algorithm.Finally,based on the self-developed dual-frequency LiDAR system,the effectiveness of the simulated signal was verified through comparison with trial data.The root mean square error of the K d value obtained by fusion algorithm inversion was 0.74 m-1,which was better than the traditional Klett method and Fernald method.The experimental results show that the proposed fusion algorithm can achieve the convergence and accuracy requirements for the inversion of the diffuse attenuation coefficient K d and can quickly calculate the LiDAR ratio without prior information about the in-situ environment.This research is helpful to the bathymetry of shallow water and the measurement of optical parameters of ocean profiles.