A Semianalytical Method for Ocean LiDAR Radiative Transfer Considering Inelastic and Polarized Scattering

Ocean LiDAR technology is of high interest and particularly promising for ocean applications. However, its application in complex oceanic environments is often limited by traditional elastic scattering mechanisms. Most existing ocean LiDAR simulation techniques focus primarily on elastic scattering, with limited attention given to inelastic scattering. This article presents a novel semianalytical Monte Carlo (SAMC) simulation method that integrates photon tracking algorithms with polarization state simulation, incorporating nonelastic scattering processes—such as Raman scattering, Brillouin scattering, and fluorescence—and polarization effects. By combining analytical solutions with numerical LiDAR simulations, the proposed semianalytical method improves both the precision and efficiency of simulations. Additionally, the method constructs models for fluorescence, Raman scattering, Brillouin scattering, and polarization scattering. These models were used to conduct a detailed analysis of nonelastic scattering and polarization scattering echo signals in stratified water, as well as the effects of chlorophyll concentration on these signals. Compared to traditional MC methods, the semianalytical approach offers obvious advantages in computational efficiency and accuracy. The study also investigates the impact of multiple scattering, stratified water, particle size distribution, field of view (FOV), and spectral bandwidth on nonelastic and polarization scattering echo signals. It highlights the significant influence of multiple scattering on signal detection accuracy and the critical role of changes in optical properties within stratified water. Nonelastic and polarization scattering signals play a crucial role in ocean LiDAR research, and the SAMC model developed in this article offers new insights and tools for the understanding and simulation of these signals.