Bio-optical relationships for the northern Adriatic Sea

The first three years of a time-series of marine bio-optical measurements performed from an oceanographic tower in the northern Adriatic Sea are used to derive empirical relationships for ocean colour applications in coastal waters. The site presents bio-optical characteristics pertaining to Case 1 and to Case 2 waters. Log linear relationships allow the diffuse attenuation coefficient for downwelling irradiance, K-Ed, at different wavelengths to be derived from its value at 490 nm. A local empirical algorithm making use of the remote sensing reflectance ratio R-rs(490)/R-rs(555) is shown to provide lower surface chlorophylla values (by a factor of 2 to 4) in the range 0.1-1.0 mg m(-3) than the SeaWiFS OC2v4 algorithm.