Analysis and validation of ocean color and aerosol properties over coastal regions from SGLI based on a simultaneous method

This paper presents a new simultaneous retrieval result of aerosol and ocean color using the SIRAW algorithm of Shi et al. (IEEE Trans Geosci Remote Sens 58:1–12, 2020) applied to multi-spectral radiance data of the Second generation GLobal Imager (SGLI) onboard the GCOM-C satellite. Satellite-retrieved Aerosol Optical Thickness (AOT), normalized water-leaving radiance (nLw), and chlorophyll- a concentration (Chl- a ) are then compared with those of the AERONET-OC observation at three sites in the coastal areas in East Asia. Results demonstrate that both the AOT and ocean color parameters from SIRAW and SGLI products are consistent with validation data, particularly with a significantly better performance of retrieved AOT from SIRAW. Due to the simultaneous correction of wind speed and use of coupled atmosphere–ocean radiative transfer model, SIRAW is promising to provide a better retrieval of nLw in sun glint contamination and avoids the negative values of nLw. We then apply the present algorithm to 250 m radiance data of SGLI to obtain aerosol and ocean color distributions in the three coastal areas and find that the present algorithm gives wider retrievable areas with more plausible AOTs than those of the standard algorithm. We also find high contrast patterns between coastline and off-shore areas and characteristic plume-type patterns of aerosol and ocean depending on the topographic structure of each area. It will be a promising future work to study spatial and temporal trends of these two characteristic patterns to understand the transportation of atmospheric and ocean color substances in the areas.