Sea Surface Carbon Dioxide off Iberian Peninsula (east North Atlantic Ocean)

The variability of the carbon dioxide in the eastern North Atlantic Ocean was investigated by studying three seasons with different hydrographical and meteorological conditions that lead to two main different situations: upwelling and downwelling. No correlation between surface pCO2 and chlorophyll was found in spring, although significant correlation was found in autumn when strong downwelling was the observed. The convergence developed over the slope produce different regimes of stability of the water column on the shelf creating areas of high and low pCO2 levels. A positive correlation (r=0.50; n=33) between surface pCO2 and chlorophyll points out during the upwelling season. High pCO2 is found when the greatest concentration of chlorophyll exists. The uptake of carbon by photosynthetic activity masks the increase of dissolved inorganic carbon concentrations in surface due to the upwelling event. Without this biological effect the increase of pCO2 during the upwelling will be even higher. Air-sea fluxes of CO2 were calculated for the three studied seasons. The average CO2 flux from the atmosphere to the ocean (0.47 mmol m.d) in the eastern margin of North Atlantic was slightly lower than those given in previous studies in the North Atlantic ocean because of the influence of upwelling.