Intercomparison of GOCI and GOCI-II TOA Radiance Data in NIR band

Abstract

The 2nd Geostationary Ocean Color Imager (GOCI-II) was launched in February 2020 and is observing the Northeast Asian Ocean and Hemisphere (full disk) with improved temporal and spatial resolution than Geostationary Ocean Color Imager (GOCI). In the radiance image observed from the top of atmosphere (TOA), which is a satellite orbit, the atmospheric radiance occupies most of the total radiance data, and the radiance containing the color of seawater is less than 10% of the total radiance. Since a 1% atmospheric radiation error causes an estimation error of sea surface reflectance of more than 10%, satellite-based ocean color remote sensing requires high atmospheric correction accuracy. In-situ data are essential for the calibration of satellite data, but the ocean is wide and difficult to observe. Therefore, satellite-based data are used to calibrate the ocean. We studied a comparison analysis using TOA(Top-of-atmosphere) radiance data of overlapping observation periods of GOCI and GOCI-II, and we will use the results for cross-calibration. If more in-situ data are accumulated in the future, we intend to derive better calibration results through comparison with in situ data. Also, it can be applied to the GOCI-II atmospheric correction update.