Spectral fitting techniques in turbid water

A technique is described for determining the near-surface concentrations of dissolved and particulate material in a turbid shelf sea by least-squares fitting theoretical reflectance spectra to the observed spectrum. The theoretical spectra are generated by running through the range of likely values of the backscattering coefficient and concentrations of mineral suspended solids (MSS), chlorophyll (CHL) and coloured dissolved organic matter (CDOM) absorption. The results show that excellent agreement can be obtained between the observed and fitted spectrum, but that the concentrations associated with the best fit bear little relationship to observed concentrations. Only in the case of backscattering is there a realistic relationship with the measured concentration of MSS. It is concluded that the technique has potential, but that the concentrations used will have to be constrained to provide useful estimates of water quality using visible band satellite images in turbid water.