Bio-optical relationships for the northern Adriatic Sea

Abstract

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_{E d}, 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 chlorophyll-a values (by a factor of 2 to 4) in the range 0.1–1.0 mg m⁻³ than the SeaWiFS OC2v4 algorithm.

Acknowledgments

CoASTS is a co-operative project between the Joint Research Centre and the Italian National Research Council. Many thanks to Stefania Grossi, Dirk van der Linde and Cristina Targa from JRC who participated in the constitution of the CoASTS dataset, to Davide d'Alimonte who ultimately contributed to data processing and to Frédéric Mélin for valuable discussions. This work was partially supported by the European Commission under contracts ENV4CT960307 and MAS3CT970087, and by NASA through grant NCC5-371.

Notes

An updated version of a paper originally presented at Oceans from Space ‘Venice 2000’ Symposium, Venice, Italy, 9–13 October 2000.