LWIR polarization characteristics of targets in sea fog via an enhanced p-BRDF model

To address the limitations of traditional polarization bidirectional reflectance distribution function (p-BRDF) models that neglect atmospheric scattering and therefore exhibit reduced accuracy under complex atmospheric conditions, this study proposes a method for analyzing the long-wave infrared (LWIR) polarization characteristics of targets in sea fog environments. The method improves the volume scattering component using the Minnaert scattering model and characterizes the spontaneous emission component through directional hemispherical reflectance. Additionally, a Mie scattering model is introduced via an enhanced Monte Carlo method. To retrieve key material parameters, a particle swarm optimization algorithm is applied to measurement data from four typical ship hull materials-5083 aluminum alloy, 316 L stainless steel, coated 316 L stainless steel, and polyethylene-under various sea fog concentrations. Simulation and experimental results indicate that when the relative azimuth angle is 180°, the degree of linear polarization (DOLP) for all four targets peaks near the Brewster angle. Under sea fog conditions, the proposed model achieves a normalized root mean square error (NRMSE) reduction of at least 14.64% compared to conventional approaches. These findings offer valuable insight for improving infrared polarization detection accuracy in complex atmospheric environments.