Extraction of water-leaving radiances from GOCI imagery for highly turbid waters using the MUMM atmospheric correction algorithm

Abstract

The Geostationary Ocean Color Imager (GOCI) area include both Case-1 waters and Case-2 waters. Some shallow coastal waters including the Yellow Sea and East China Sea can be highly turbid due to wind or tidal driven sediment resuspension. Therefore there is a need to develop atmospheric correction techniques for turbid Case-2 waters as well as for clear waters.The standard atmospheric correction algorithm for clear waters assumes that water-leaving radiances be negligible at near-infrared (NIR) wavelengths. However, it is well-known that, in turbid waters, the water-leaving radiances at the NIR wavelengths are significant, and also the spectral slope of the top-of-the-atmosphere radiances is usually greater than that of atmospheric aerosols only. This would produce large errors in the water-leaving radiances if the standard atmospheric correction were adopted to turbid Case-2 waters.The MUMM atmospheric correction algorithm, which had been developed for SeaWiFS data processing for turbid waters, uses two NIR bands. It assumes the homogeneity of the ratio of both aerosol reflectance and water-leaving radiance at near-infrared wavelengths over the region of interest. In this study, we evaluated the MUMM atmospheric correction algorithm in a coastal ocean area off the west-south part of Korean peninsula(Mokpo) which covers Case-1 and Case-2 waters.n. Therefore there is a need to develop atmospheric correction techniques for turbid Case-2 waters as well as for clear waters.The standard atmospheric correction algorithm for clear waters assumes that water-leaving radiances be negligible at near-infrared (NIR) wavelengths. However, it is well-known that, in turbid waters, the water-leaving radiances at the NIR wavelengths are significant, and also the spectral slope of the top-of-the-atmosphere radiances is usually greater than that of atmospheric aerosols only. This would produce large errors in the water-leaving radiances if the st