NEW APPROACH TO CHLOROPHYLL-A DETERMINATION IN SHALLOW COASTAL WATERSBY REMOTE-SENSING

A new conceptual approach for chlorophyll a estimation by remote sensi ng in coastal shallow waters has been developed on the basis that the coefficient of water attenuation can be estimated from the signal rece ived by the sensor avoiding the influence of bottom radiance. It has b een tested at the Mar Menor, an oligotrophic coastal lagoon located in the SE of Spain, based on a flight synchronized with sampling of wate r and substrate. The spectral information was obtained from Daedalus 1 268 multispectral scanner which configuration was similar to CZCS. Sam ples from water and substrate were analysed in the laboratory to quant ify environmental parameters. The lagoon has an average depth of 3.5 m and a maximum depth of 6.6 m. Bottoms are mainly covered by dense Cau lerpa prolifera-Cymododea nodosa beds. The lagoon surface, which is ab out 135 km(2), was covered with five aeroplane passages. The proposed approach assumes that the coefficient of water attenuation (K) is not constant throughout the scene and these variations are related to chlo rophyll a concentration. A new method to obtain K for each pixel was p reviously developed.