Using three-band model to retrieve chlorophyll-a of Yantai coastal waters

Abstract

It is challenging that accurate assessment of chlorophyll-A concentration by remote sensing in coastal waters. Chla concentration is commonly retrieved by blue-green ratio in open ocean waters. And this method is efficient in open ocean waters. But this method is confined when applied to coastal or inland waters, because of abundant variable CDOM and tripton. It is very difficult to retrieve chla of coastal or estuary waters because of overlap of absorption and backscattering caused by CDOM and tripton. Dall€™Olmo et al put forward a semi-analytical retrieval model of chla, three-band model. The conceptual three-band model has been successfully applied to estimate chla in turbid and eutrophic waters by tuning the band position in accordance with the spectral properties.The aim of this paper is to testify the three-band model that could resolve this problem. The three-band model was tuned in accord with optical properties and the bands were optimized for accurate estimation. Finally, we found a good linear relationship between chlorophyll-A and three-band model, with the determination coefficient of 0.63 and the RMSE of 2.22μg·L-1. Furthermore, the in situ spectral data was averaged to the band range of MERIS (band7, band9 and band10) and developed a simulated threeband model. A good linear relationship could be found between [(B7-1-B9-1)×B10] and chlorophyll-a, with the determination coefficient of 0.59 and the RMSE of 0.72μg·L-1. The findings demonstrated that the three-band model of MERIS could be applied to retrieve chlorophyll-A concentration of Yantai coastal waters.