An Ocean Optical Parameters Inversion Algorithm Based on Pulse Broadening Match With Varying System Impulse Response Functions for ICESat-2

The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) carries the new generation photon-counting lidar payload, the Advanced Topographic Laser Altimeter System (ATLAS). After after-pulse correction, the water column profile acquired by ATLAS can be used to derive vertical profiles of ocean optical parameters. However, the stability and robustness of the correction method across different sea areas could be improved. This study analyzes the broadening effect of sea surface signals caused by varying sea states. It employs land signals with broadening characteristics similar to those of the sea surface as the system impulse response function (SIRF) to perform after-pulse correction on water column profiles. By matching pulsewidths, the proposed algorithm reduces the impact of sea surface broadening on after-pulse correction results. Internal consistency validation among ATLAS’s three strong beams is conducted and achieves a correlation coefficient exceeding 0.8 in the Black Sea, the Atlantic Ocean, and the Pacific Ocean. Meanwhile, the ocean optical parameter inversions are compared and validated with the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Biogeochemical Argo (BGC-Argo) data. The mean relative errors (MREs) of inversion results in the three sea areas are approximately 20%, representing a reduction of over 30% compared to the traditional algorithm. Finally, a sensitivity analysis of the broadening matching algorithm and cumulative length confirms the algorithm’s robustness. The ocean optical parameters inversion algorithm based on pulse broadening matching lays the foundation for high-precision inversion of parameters, such as chlorophyll concentration, and provides a reference for future data processing in related systems.