Ocean color studies of the Mediterranean Sea: from CZCS to SeaWiFS

摘要

Data collected by the CZCS (79-85) and the SeaWiFS (98) highlight the relations between bio-geo-chemical and physical processes of the Mediterranean Sea. A comparison of the pigment concentration historical record with surface temperature and wind speed, from the AVHRR (82-91), GEOSAT (86-89), ERS-1 (92-95) and TOPEX (93-97) archives, differentiate between geographical provinces corresponding to (1) areas under the direct influence of coastal interactions; (2) regions of enhanced characteristics (i.e. Ligurian/Provencal/Balearic sub-basin, Adriatic Sea, Aegean Sea), linked to interactions with (northern) continental margins and prevailing winds (i.e. Mistral Bora, Etesians); and (3) open sea, oligotrophic areas, characterized by frontal structures and, in the eastern basin, by a permanent mesoscale eddy field. The trends in these provinces indicate two main seasons, with extreme conditions in winter and summer, and transition periods in spring and autumn. The general pigment cycle is similar to that of a subtropical basin, where light is never a limiting factor, but nutrients always are. Some near-coastal provinces have a distinct seasonality, e.g. that of a subpolar basin in the north-west, with enhanced spring and fall blooms. This view is supported by current SeaWiFS data, which show that features such as river plumes, filaments and permanent gyres are recurrent and maintain their characteristics over the long term.