Posters

Poster Session 4, Thursday, October  6, 11:00–12:40

Poster 52

Preliminary Improvement of Geostationary Ocean Color Imager-II (GOCI-II) Radiometric Calibration Process

The Geostationary Ocean Color Imager-II (GOCI-II) on board the Geo-KOMPSAT-2B (GK2B) satellite is successfully launched in February of 2020. The observed instrument responses in GOCI-II satellite sensors gradually decrease over time as a result of exposure to continuous radiation, which is corrected by the Solar Diffuser (SD), and its performance is monitored by the Solar Diffuser Stability Monitor (SDSM) system. Currently, GOCI-II SD computes the radiance by applying the time-independent gain parameter, so there is a problem that the aging of sensors over time is not considered in this process. In this study, the GOCI-II radiometric calibration algorithm is improved by applying a time-varying scale factor (called F-factor) considering sensor degradation over time in calculating the observed instrument responses to top of atmosphere radiance. First, SD aging factor is derived using gain values calculated from SD and DAMD. As a result of monitoring the SD aging factor, it could be confirmed that it depends on time, azimuth angle, and wavelength. We develop a model for azimuth angle correction to produce look-up table and calculate angle-independent aging factors. As a result, we improve the radiance which the time-varying scale factor is applied and the trend of radiance is analyzed. Through consideration of sensor degradation, we will provide reliable GOCI-II ocean color products in long-term scale trend analysis.

*Minsang Kim, Korea Institute of Ocean Science and Technology, [email protected], 0000-0002-3852-8068 

Myung-Sook Park, Korea Institute of Ocean Science and Technology, [email protected] 

Jae-Hyun Ahn, Korea Institute of Ocean Science and Technology, [email protected] 

Sun-Ju Lee, Korea Institute of Ocean Science and Technology, [email protected]

Gm-Sil Kang, Korea Aerospace Research Institute, [email protected]