정지궤도 해양위성(GOCI)의 비행모델을 이용한 궤도상 관측 및 복사보정 성능 예측

Abstract

The Geostationary Ocean Colour Imager (GOCI) is a visible band ocean colour instrument onboard theCommunication, Ocean, and Meteorological Satellite (COMS) scheduled to be in operation from early 2010. Theinstrument is designed to monitor ocean water environments around the Korean peninsula in high spatial and temporalresolutions. We report a new imaging and radiometric performance prediction model specifically designed for GOCI.The model incorporates the Sun as light source, about 4000km x 4000km section of the Earth surrounding the Koreanpeninsula and the GOCI optical system into a single ray tracing environment in real scale. Specially, the target Earthsection is constructed using high resolution coastal line data, and consists of land and ocean surfaces with reflectivitydata representing their constituents including vegetation and chlorophyll concentration. The GOCI instrument in the IRTmodel is constructed as an optical system with realistic surface characteristics including wave front error, reflectivity,absorption, transmission and scattering properties. We then used Monte Carlo based ray tracing computation along thewhole optical path starting from the Sun to the final detector plane, for simultaneous imaging and radiometricperformance verification for a fixed solar zenith angle. This was then followed by simulation of red-tide evolutiondetection and their radiance estimation, in accordance with the in-orbit operation sequence. The simulation results provethat the GOCI flight model is capable of detecting both image and radiance originated from the key ocean phenomenaincluding red tide. The model details and computational process are discussed with implications to other earthobservation instruments.