An inversion method for reflectance in stratified turbid waters
Abstract:Most methods for interpreting water-leaving reflectance assume vertical homogeneity in the water column. This approach is relevant to quite homogeneous waters or to very turbid waters where reflectance is related to the optical properties of a thin upper surface layer. In weakly turbid and stratified waters, water-leaving reflectance depends on the vertical profile of each optically significant component. This study presents a semi-empirical inversion method to estimate Total Suspended Matter (TSM) concentrations from reflectances in sediment-dominated and stratified waters. The method derives from the concept of a remote sensing estimate of concentration, which is calculated from the profile of suspended matter concentration and from the profile of diffuse attenuation coefficient. A simplification is introduced when the diffuse attenuation profile is not known. The simplified method can be applied to satellite data to retrieve 'optically-effective' concentrations showing better correlations with reflectances than subsurface concentrations. The method is extensively described in the paper and is applied, as an example, to field measurements and to SPOT data over the Ebro river mouth area. Its potential use in connection with numerical modelling of suspended sediment transport is also discussed.
Document Type: Research Article
Affiliations: Laboratoire de Sondages Electromagnétiques de l'Environnement Terrestre, Université de Toulon et du Var, BP 132, 83957 La Garde cedex, France
Publication date: February 1, 2003