The Clorophyll remote sensing by satellite requires an accurate modelling of the athmospheric effects. For an uncloudy scene the aerosol diffusion is considered to be the principal effect. When dealing with enclosed seas like the Mediterranean, anthropogenic or non oceanic aerosol effects, including dust transportation from Sahara must be taken into account. The sea surface radiance and the optical thickness were obtained by a SIMBADA radiometer (Laboratoire d'Optique Atmospherique, CNRS, Lille, France) measuring 11 spectral bands centered at 350, 380, 412, 443, 490, 510, 565, 620, 670, 750 e 870 nm. The aereosol content may be detected by analyzing the spectral variations of the optical thickness. Measurements were taken during the daylight hours and with unclouded sun. The 12:00 measurements will be used for the SeaWiFS Satellite 'sea-truth'.