An In-Orbit Radiometric Calibration Method of the Geostationary Ocean Color Imager

The Geostationary Ocean Color Imager (GOCI) has been developed for the first time to provide multispectral data which is useful to detect, monitor, and predict short-term changes of coastal ocean environment around the Korean Peninsula from a geostationary platform. In this paper, an in-orbit solar calibration method for GOCI is introduced. Based on the radiometric model of GOCI, solar calibration method using onboard calibration devices has been constructed. A nonlinear radiometric model has been validated using test results obtained during ground tests. The gain parameters of the GOCI radiometric model will be continually updated by the in-orbit solar calibration. The GOCI is equipped with two onboard calibration devices: Solar Diffuser (SD) and Diffuser Aging Monitoring Device (DAMD). The SD, which is located in front of a pointing mirror covering full aperture of the GOCI, is used for calibrating end-to-end radiometric response. The DAMD, which covers partial aperture, detects a potential degradation of the SD.