정지궤도해색위성 자료를 위한 대기보정 및 BRDF 보정 방법 연구

Abstract

The standard atmospheric correction (SAC) algorithm designed for the CASE-I water area (open ocean) turn out to be unsuccessful for the CASE-II water area (Korean coastal ocean). So new atmospheric correction method for the turbid water is required for the Geostationary Ocean Color Imager (GOCI). Additionally geostationary ocean satellite, unlike other sun-synchronous polar-orbit satellites, will be able to take image data for a large region in many times during a day, almost every hour. In the case of a geostationary satellite, target region and satellite position are fixed but the location of sun is changed always. So the ocean signal power of one given specific target point is depended on time. In this study, we developed new atmospheric correction and the signal correction method using Bidirectional Reflectance Distribution Function (BRDF) for the GOCI data. For the new atmospheric correction, we use modified version of the Spectral Shape Matching Method (SSMM) previously developed by Ahn and Shanmugam (2004). And for the BRDF correction, one signal value of selected pixel point of target region of GOCI would be set up a standard, and the ratio of all remained pixel point can be calculated. This relative ratio is bidirectional factor, and the result of modeling of spatiotemporal variation of bidirectional factor is shown in this study.