Title: Principles of the COMS data calibration and the calibration algorithm development Author(s): Kyoung-Wook Jin, Gwang-Hyeok Ju, Koon-Ho Yang
COMS (Communication, Ocean and Meteorological Satellite) program has great significance of the first geostationary satellite development project in Korea. In addition to build a solid basis for the technological leap from LEO (Low Earth Orbit) satellite developments pursued so far, the program will provide valuable scientific data which include near real-time meteorological data and unprecedented high resolution ocean color information over the Korea peninsular. To obtain well-calibrated data, the development of calibration algorithm which meets user¶s requirements is essential. Data calibration process is divided into two main parts:
radiometric and geometric calibrations. Radiometric calibration is required to transfer raw data represented as digital numbers into equivalent scientific data (reflectivity or radiance) correctly. MI (Meteorological Imager) instrument on COMS has one visible and four infrared channels. Visible and infrared channels have different calibration schemes. Visible channel needs a vicarious calibration based on a moon image processing unlike the infrared one which has an on-board calibration using a black-body target. During the calibration, additional processing (e.g. midnight effect correction) to reduce errors is performed. On the other hand, geometric calibration is crucial to pinpoint measurement locations accurately projected on the Earth. For the geometric calibration, INR (Image Navigation and Registration) system, which contains complicated modules such as orbit model, attitude model and linear error correction, to fix the geometric uncertainties during the COMS¶s measurement is designed.
In this paper, the principles of COMS data calibration (radiometric and geometric) algorithms will be introduced.
Major tests according to development stages of the calibration algorithms will be presented. The potential applications of the calibrated COMS data will be briefly discussed as well.
