Sea surface carbon dioxide off the Iberian Peninsula (North Eastern Atlantic Ocean)

The variability in carbon dioxide in the eastern North Atlantic Ocean was a nalysed during three seasons with differing hydrographical and meteorologic al conditions that corresponded to upwelling and downwelling. No correlatio n between surface pCO(2) and chlorophyll was found in spring, although a si gnificant correlation was found in autumn when strong downwelling was obser ved. The convergence that developed over the slope during strong downwellin g, produced different regimes of water column stability on the shelf and cr eated areas of high and low pCO(2). A positive correlation (r(2) = 0.50; n = 33) between surface pCO(2) and chlorophyll occurred during the upwelling season. High pCO(2) is found when the greatest concentration of chlorophyll exists. The uptake of carbon by photosynthetic activity masked the increas e in dissolved inorganic carbon concentration at the surface due to the upw elling event. Without this biological input, the increase in pCO(2) during the upwelling would be even higher. Air-sea fluxes of CO2 were calculated f or the three studied seasons. The average CO2 flux from the atmosphere to t he ocean (0.47 mmol m(-2) d(-1)) in the eastern margin of North Atlantic wa s slightly lower than those given in previous studies in the North Atlantic ocean because of the influence of upwelling. (C) 1999 Elsevier Science B.V . All rights reserved.