ALGAL PIGMENT DISTRIBUTION AND PRIMARY PRODUCTION IN THE EASTERN MEDITERRANEAN AS DERIVED FROM COASTAL ZONE COLOR SCANNER OBSERVATIONS

About 300 coastal zone color scanner (CZCS) scenes, gathered over the eastern Mediterranean basin mostly during the years 1979-1981, have be en processed from level 1 by using improved pixel-by-pixel procedures for the atmospheric correction and pigment retrieval. The seasonal evo lution of the upper ocean pigment concentration is described and analy zed within the whole basin and its subbasins. From the chlorophyll con centration in the top layer, and by using statistical relationships, t he depth-integrated pigment content is estimated and used in conjuncti on with a light-photosynthesis model to estimate the carbon fixation. The model relies on a set of physiological parameters, selected after the validation of the light-photosynthesis model and not on locally me asured parameters. Additional information needed in the modeling are t he photosynthetically available radiation (computed from astronomic an d atmospheric parameters, combined with a cloud climatology), sea temp erature and mixed-layer depth (taken from Levitus (1982)). Actually, t he model is used to generate look-up tables in such a way that all pos sible situations (concerning available radiation, chlorophyll concentr ation, and temperature) are covered. The appropriate situation associa ted with any pixel is selected from these tables to generate primary p roduction maps. Despite a relatively good spatial coverage, studying t he interannual variability of the pigment distribution and primary pro duction appeared to be impossible. Therefore 12 ''climatological'' mon thly chlorophyll maps have been produced by merging the data correspon ding to several years. The carbon fixation rates in each of the subbas ins have been computed on a monthly basis, and annual mean values deri ved thereafter. The primary production values are compared with sparse field determinations. They are also compared with those previously de rived for the Western basin, also by using CZCS data (Morel and Andre, 1991). When put together, these companion works provide a kind of rec ord of the trophic status of the entire Mediterranean Sea in the early 1980s. Ocean color sensors to be launched next, like SeaWIFS, will al low the seasonal and interannual variabilities in the late 1990s to be addressed.