When using in-situ methods such as the use of spectrometers aboard a ship, aircraft or satellites to estimate suspended matt,er (especially phytoplankton concentrations) in waters it is necessary t o know the corresponding correlations between the matter concerned and t.he spectral reflectance R (1)
or colonr indices R(Ai)/R(Aj).Therefore, ship-borne experiment,s were carried out on mesotrophic and eut'rophic waters. The following parameters were measnred: reflectance a t the wavelengths 450, 550, 670, 705 nm, Secchidisk transparency, chlorophyll-a concentration, fluorescence, extinction, and scattering.