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

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

Chlorophyll - A vertical distribution of Yantai coastal waters

Many researchers have studied the properties of chlorophyll - a vertical distribution in open ocean waters by now, and little is found for coastal waters. In the study, the chlorophyll - a vertical distribution of Yantai coastal waters is analyzed and a polynomial model is used to appraise the trend. Furthermore, the Gaussian model according to open waters is used to testify the practicability for coastal waters. The ratio between chlorophyll - a and turbidity is also discussed in order to predict the distribution trend. Finally, some conclusions could be achieved: A chlorophyll - a maximum in vertical direction could be seen and the maximum appears at about 6∼8 meter depth in our research areas. The chlorophyll - a vertical distribution is similar to open ocean waters. Secondly, the euphotic layer is about 6∼8 meter depth. Thirdly, under the depth of maximum chlorophyll - a concentration, chlorophyll - a concentration has negative correlation to the turbidity concentration in vertical direction. Based on above conclusion, the total chlorophyll - a could be achieved by calculating definite integrate of the simulation functions. This verifies the relationships of the surface and total chlorophyll - a concentration, which is the basis of primary production by the method of remote sensing. © 2013. The authors