In this study, the potential of MEdium Resolution Imaging Spectrometer (MERIS) to describe variations of optically active substances over Alqueva artificial
lake is investigated. Limnological laboratory analyses of the water samples
collected monthly, from 2003 to 2006, are used in combination with MERIS. The
water surface spectral reflectance is derived from Level1b MERIS data, using
radiative transfer calculations to account for the atmospheric effects. The lake
water spectral surface reflectance is combined with laboratory analyses of cyanobacteria total densities as well as chlorophyll a concentrations and empirical
algorithms for both quantities are derived. The results obtained are compared with independent laboratory analyses from 2007, with good correlation coefficients
obtained both for cyanobacteria (R ¼ 0.93) and chlorophyll a (R ¼ 0.80).
The methodology proposed here has been developed to inexpensively monitor
Alqueva Reservoir water quality in terms of cyanobacteria and chlorophyll a on
a regular basis, and to provide useful information to the authorities
