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Analysis of remote sensing data for coastal monitoring

Coastal monitoring has been improved, with special reference to pollution situations, the development of methods for the analysis of remote sensing data on sea colour, and the development of bioptical algorithms relating sea colour to water composition. A radiometer is being developed for the detection of the blooms of the marine cyanobacterium tricherdesmium in oligotrophic case 1 waters. A simulation study has been carried out using a 3 component model of sea colour, explicitly accounting for the contributions of the main optical parameters (ie phytoplankton, nonchlorophyllous particles and yellow substance). The results obtained indicated that algorithms operating on the data recorded should have the capability to discriminate pixels containing trichodermium at concentrations down to 0.1 mg m{-3} chlorophyll and yield estimates of the concentration. The validity range has been explored by a sensitivity analysis. Modifications have been made to improve the procedure used for absorption measurements of aquatic particles retained on glass fibre filters. Beam transmission and beam reflection measurements were combined in order to remove the spurious contribution caused by sample back scattering, by use of a commercial integrating sphere attachment to the dual beam spectrophotometer. The sample was bleached with a sodium hypochlorite solution, which proved to be simple, rapid and highly effective. Calculation of irradiance distributions was studied for cases of stratified water with a diffusely reflecting bottom. The 2 stream method of solving the radiative transfer equation was adapted to the calculation of light distribution in vertically homogenous water bodies. The solution in such cases can be given in analytical form and will then allow study of the influence of various parameters (eg bottom reflectivity, ratio of diffuse to direct solar incoming radiance and inherent water optical properties) on the spatial distributions of the fluxes. This method was then extended to stratified water bodies consisting of homogenous layers, and could therefore be used in the estimation of errors in pigment retrieval when water stratification and bottom reflectance cannot be neglected.

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Record Number: 12426 / Last updated on: 1995-06-19
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