Global Polarized Radiance of Ice Clouds in the Visible and Near-Infrared Bands and Optimal Ice Crystal Model Parameters

This study investigates the polarized radiance of ice clouds in visible and near-infrared bands, with a focus on optimizing ice crystal model parameters. We developed a comprehensive optical property database of 1,071 super-spheroid ice crystals, considering variations in aspect ratio, roundness, and surface roughness. Using observations and cloud property data from the Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) and Moderate-resolution Imaging Spectroradiometer (MODIS), we analyzed ice cloud radiative properties and derived optimized ice crystal models. These models exhibit improved spectral consistency and higher accuracy in replicating satellite-measured polarized radiance across all three wavelengths (0.490, 0.670, and 0.865 μm). Key findings reveal that the optimal ice crystal shapes vary systematically with latitude and seasonal changes, enabling significantly better fits to observational data. This study establishes the first optically consistent ice crystal models applicable to polarization studies, thereby advancing the radiative transfer modeling of ice clouds.