Ocean Scanning Multi-spectral Imager (OSMI) post-launch radiometric responsivity analysis

Ocean Scanning Multi-spectral Imager (OSMI) is a payload on the KOrean Multi-Purpose SATellite (KOMPSAT) launched 21 December 1999. OSMI will perform worldwide ocean color monitoring for the study of biological oceanography. OSMI acquires image data of 6 spectral bands at a time by performing whisk-broom scan with a ground sample distance (GSD) of 1 km and a ground swath width of 800 km during 20% duty cycle. For flexible mission OSMI has on-orbit spectral band selectability and programmable gain and offset. OSMI performs solar calibration and dark calibration for on-orbit instrument calibration. The post-launch radiometric responsivity of OSMI is analyzed at various gain settings in the viewpoint of the instrument developer for the instrument calibration. This analysis is carried out based on the laboratory performance measurement results for the primary spectral bands of OSMI and by using linear curve fitting method with the OSMI on-board calibration data acquired during the early operation phase. This analysis is considered to be useful for the OSMI image data calibration and user´s understanding about OSMI image quality