Optical remote sensing is of invaluable help in understanding the marine environment and its biogeochemical and physical processes. The Coastal Zone Color Scanner (CZCS), which operated on board the Nimbus-7 satellite from late 1978 to early 1986, has been the main source of ocean colour data. Much work has been devoted to CZCS data processing and analysis techniques throughout the 1980s. After a decade of experience, the Productivity of the Global Ocean (PGO) Activity - which was established in the framework of the International Space Year 1992 (ISY '92) by SAFISY, the Space Agency...