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In this study, we present an inverse data modelling for the optical properties of the eutrophic water from reflectance spectra in Nanhu Lake of Changchun, China. The lake water in Nanhu Lake is optically dominated by scattering from suspended matter, whereas the lake water is dominated by absorption from phytoplankton (CHLa), total suspended matter (TSM), and coloured dissolved organic matter (CDOM or referred to as yellow substance). The main reason is that the Nanhu Lake is highly affected by the input from rivers and drainage systems from the area of Changchun, which discharge a high concentration of CDOM, nutrients, and mineral suspended solids. The reflectance spectra at 400–900 nm were measured in Nanhu Lake using the ASD-field spectroradiometer. An inverse data modelling was applied to analyse the optical properties of the eutrophic lake water. The result shows that the optical properties of the eutrophical water can be effectively modelled from reflectance spectra for the eutrophic lake. However, further studies are still needed to refine the method for determining the optical properties of eutrophic waters under study. [ABSTRACT FROM AUTHOR]

We present an algorithm from spectral measurements of upwelling water light to estimate the concentration of optically active material (OAM) such as chlorophyll-a (chl-a). The problem of chla concentration retrieval is modelled using a simulated hyperspectral sensor based on spectral measurements. Sensor noise is taken into account during the algorithm development for the best linear estimation of concentration mean and residual variance. In addition, it requires the joint distribution of radiance spectra and chl-a concentration in the algorithm development. This distribution can be obtained by simulation using water-leaving radiance models. The result shows that sensor noise greatly decreases the accuracy of chla concentration retrieval. But the accuracy can also be improved if a priori information concerning observation conditions is known and included in the algorithm. The effects of sensor noise in spectral measurements on retrieval of chl-a concentration are analysed and assessed in the study. This method is applied to the optical properties of the eutrophic water in Nanhu Lake of Changchun, China. The eutrophic water of Nanhu Lake is mainly impacted by the input from rivers and drainage systems from the area of Changchun, which discharge a high concentration of nutrients, mineral suspended solids, and dissolved organic matter (DOM or referred to yellow substance). We measured reflectance spectra (400–900 nm) of Nanhu Lake using the ASD-field spectroradiometer from April to October in 2004. The application of this algorithm shows that neglecting the sensor noise greatly underestimates the accuracy of chl-a retrieval in the study. [ABSTRACT FROM AUTHOR]

In this study, we present the optical properties of the eutrophic water in Nanhu Lake of Changchun, China, as a case study done in September 2003 and April 2004. The lake water in Nanhu Lake is optically dominated by scattering from suspended matter, and the lake water is dominated by absorption from phytoplankton (CHL-a), total suspended matter (TSM) and yellow substance (or so-called CDOM). The main reason is that the Nanhu Lake is highly affected by the input from rivers and drainage systems from the city of Changchun which discharges a high concentration of CDOM, nutrients, and suspended mineral solids. We measured the spectral characteristics (400–900 nm) of Nanhu Lake using the ASD-field spectrometer and analyzed the optical properties of the eutrophic water. The spectral measurements will be continued during the period of 2004–2005. Further studies are still needed to refine the method for determining the optical properties of inland waters under study. [ABSTRACT FROM AUTHOR]