DAYTIME VARIATIONS OF NDVI FROM GEOSTATIONARY OCEAN COLOR IMAGER (GOCI) DATA

摘要

Geostationary satellite images are beneficial to produce high temporal resolution cloud-free NDVI composites. However, NDVI values obtained from the hourly GOCI images show large daytime variations from morning to late afternoon. In this study, the diurnal variations of NDVI were analyzed over several land cover types. NDVI value was calculated by reflectance of GOCI band 5 (red) and band 8 (NIR). Five cover types including forest, crop land, fallow ground, grassland, and desert were selected and the hourly NDVI values were extracted from the atmospherically corrected GOCI images of two clear days. The magnitude and pattern of diurnal variations of NDVI were different by cover types while the lowest NDVI was found around local solar noon time. Daytime NDVI variation was more apparent in vegetation covers like forests than in desert and grassland.