GOCI-II atmospheric correction and its system vicarious calibration: current status and future directions

The Geostationary Ocean Color Imager series (i.e., GOCI and GOCI -II) is the first spaceborne ocean color sensor capable of capturing daytime images with unprecedented temporal resolution and has contributed significantly to advancing our understanding of oceanic and coastal dynamics. The ability to monitor these environments through high-frequency observations has been particularly valuable for studying short-term variability in biological and physical processes. Atmospheric correction is an essential step for retrieving accurate ocean color information, as it compensates for atmospheric scattering and absorption effects in top-of-atmosphere radiance measurements. The GOCI-II atmospheric correction algorithm is extension of the previous method for GOCI, incorporating enhancements in aerosol correction and an iterative optimization scheme for turbid waters. After correcting for sensor degradation, system vicarious calibration (SVC) gains are applied using the SeaWiFS vicarious calibration method, based on <i>R_rs</i> data from the well-calibrated sensors VIIRS and MODIS-Aqua. The calibrated atmospheric correction is then rigorously validated using in situ radiometric data collected over both clear and turbid waters through various research cruises, as well as the AERONET-OC dataset.