GOCI in-orbit radiometric calibration status after four-year operation

Abstract

The first spaceborne imager for ocean color remote sensing in Geostationary Earth Orbit (GEO), GOCI (Geostationary Ocean Color Imager)/COMS (Communication, Ocean and Meteorological Satellite), is successfully operated over the four years since its launch in June 2010. In order to fulfill the ocean color monitoring mission in geostationary orbit, GOCI implements 2D CMOS FPA (Focal Plane Array) with 2 million pixels, which enables staring capture method with 700km x 700km IFOV (Instantaneous Field of View) and 500m GSD (Ground Sampling Distance) over the center of the coverage area (130˚E, 36˚N) which corresponds to 380m GSD over the nadir. GOCI can observe Korea, Japan, and coastal region of China with 4 x 4 slot image acquisitions. One slot image of GOCI is equivalent to IFOV, and size of coverage area with 4 x 4 slot images is 2,500km x 2,500km including overlap area among adjacent slot images. GOCI equips 8 spectral bands. In visible wavelength region from 402nm to 685nm, 6 spectral bands are implemented on GOCI with the bandwidth of 20nm (for B1 ~B5) or 10nm (for B6, central wavelength at 680nm). Two spectral bands located in NIR wavelength region with band center at 745nm and 865nm are mainly used for the atmospheric correction. In-orbit calibration method of GOCI is solar calibration using onboard Solar Diffuser (SD) and Diffuser Aging Monitoring Device (DAMD) equipped in the Shutter Wheel since its launch in June 2010. In order to fulfill the ocean color monitoring mission in geostationary orbit, GOCI implements 2D CMOS FPA (Focal Plane Array) with 2 million pixels, which enables staring capture method with 700km x 700km IFOV (Instantaneous Field of View) and 500m GSD (Ground Sampling Distance) over the center of the coverage area (130˚E, 36˚N) which corresponds to 380m GSD over the nadir. GOCI can observe Korea, Japan, and coastal region of China with 4 x 4 slot image acquisitions. One slot image of GOCI is equivalent to IFOV, and size of coverage area with 4 x 4 slot images is 2,500km x 2,500km including overlap area among adjacent slot images. GOCI equips 8 spectral bands. In visible wavelength region from 402nm to 685nm, 6 spectral bands are implemented on GOCI with the bandwidth of 20nm (for B1 ~B5) or 10nm (for B6, central wavelength at 680nm). Two spectral bands located in NIR wavelength region with band center at 745nm and 865nm are mainly used for the atmospheric correction. In-orbit calibration method of GOCI is solar calibration using onboard Solar Diffuser (SD) and Diffuser Aging Monitoring Device (DAMD) equipped in the Shutter Wheel