Prelaunch characterization of the Geostationary Ocean Color Imager

Abstract

The instrument level ground test of the Geostationary Ocean Color Imager(GOCI) has been completed and integrated onto the Communication, Ocean and Meteorological Satellite(COMS) which is scheduled for launch in late 2009. In order to monitor the short-term biophysical phenomena with better temporal and spatial resolution, The GOCI has developed with eight VNIR bands, 500m GSD, and 2500km×2500km coverage centered at 36°N and 130°E. The GOCI planned to observe the full coverage region by every hour in daytime, and provide 8 images in daytime during single day. The GOCI ground test campaign for characterization and calibration has been performed by Korea Aerospace Research Institute(KARI), Korea and EADS Astrium, France. Korea Ocean Research & Development Institute(KORDI) has verified that test results satisfy all the GOCI performance requirements(Ex. MTF, SNR, Polarization, etc.) requested by KORDI. The GOCI has been sufficiently characterized under both of ambient and thermal-vacuum environments in order to develop the on-orbit radiometric calibration algorithm. GOCI radiometric model has been finalized with 3rd order polynomial. Because solar calibration is the on-orbit radiometric calibration method of the GOCI, Solar Diffuser made of fused silica and Diffuser Aging Monitoring Device(DAMD) are implemented as on-board calibration system. Diffusion factor of the Solar Diffuser and DAMD with respect to the solar incident angle, wavelength, and pixel location has been successfully characterized. Diffuser aging factor has been calculated for the compensation of the diffuser degradation by space environment. Diffusion factor of Solar Diffuser and DAMD, and diffuser aging factor characterized during prelaunch ground test are implemented into the GOCI radiometric calibration S/W developed by KORDI.