SAMC: A Novel Semi-Analytical Method for Simulating Full-Polarization LiDAR Signals in Marine Environments

This paper presents a novel Semi-Analytical Monte Carlo (SAMC) method developed for simulating the radiative transfer of full-polarization marine LiDAR signals within complex marine environments. Traditional marine LiDAR techniques, which predominantly rely on the intensity and linear polarization of backscattered signals, encounter limitations in complex settings. To acquire more detailed particulate morphological information, full-polarization LiDAR was introduced by incorporating circular polarization observation capabilities in recent years. However, the comprehensive calculation of full Stokes vectors brings about several inherent drawbacks, such as computational inefficiency and slow convergence. To address these issues, the SAMC method combines photon tracing with semi-analytical full polarization state tracking. It innovatively introduces polarization direction and phase difference variables into the radiative transfer process, thereby enabling the simulation and modeling of circular polarization echo signals. Based on the SAMC model, this study carried out simulation experiments regarding the transmission of lasers with different initial polarization states in water bodies. The impacts of LiDAR parameters, chlorophyll concentration, particle size range, and solar background light on full-polarization backscattered signals were analyzed. The results indicate that changes in polarization states are closely related to chlorophyll concentration and particle size, and multiple scattering effects have a significant influence on full-polarization signals. Moreover, the study explored the influence of the receiver field of view on signal quality and the discrimination ability of full - polarization channels for particles of different sizes. The unique advantages of circular polarized light in resisting solar background interference were also analyzed. This research not only conducts an in-depth analysis of the underwater full-polarization light transmission mechanism but also provides scientific support for the calibration of full - polarization LiDAR backscattered signals. The capacity to distinguish between different particle sizes using full-polarized channels offers a promising approach for the optical remote sensing of marine particle size distributions. The circular polarization's resistance to solar interference and its ability to maintain signal integrity under bright sunlight conditions represent significant advantages for marine remote sensing applications.