Temporal and spatial variations of oceanic pCO₂ and air-sea CO₂ flux in the Greenland Sea and the Barents Sea

In order to elucidate the seasonal and interannual variations of oceanic CO₂ uptake in the Greenland Sea and the Barents Sea, the partial pressure of CO₂ in the surface ocean (pCO₂^sea was measured in all seasons between 1992 and 2001.We derived monthly varying relationships between pCO₂^sea and sea surface temperature (SST) and combined them with the SST data from the NCEP/NCAR reanalysis to determine pCO₂^sea and air-sea CO₂ flux in these seas. The pCO₂^sea values were normalized to the year 1995 by assuming that pCO₂ sea increased at the same growth rate (1.5 μatm yr¹.) of the pCO₂ in the air (pCO₂ air) between 1992 and 2001. In 1995, the annual net air-sea CO₂. fluxes were evaluated to be 52 ± 20 gC m² yr¹ in the Greenland Sea and 46 ± 18 gC m² yr¹ in the Barents Sea. The CO₂ flux into the ocean reached its maximum in winter and minimum in summer. The wind speed and ΔpCO₂ (=pCO₂^air - pCO₂^sea) exerted a greater influence on the seasonal variation than the sea ice coverage. The annual CO₂ uptake examined in this study (70°-80°N, 20°W-40°E) was estimated to be 0.050 ± 0.020 GtCyr^-1 in 1995. The interannual variation in the annual CO₂ uptake was found to be positively correlated with the North Atlantic Oscillation Index (NAOI) via wind strength but negatively correlated with ΔpCO₂ and the sea ice coverage. The present results indicate that the variability in wind speed and sea ice coverage play a major role, while that in ΔpCO₂ plays a minor role, in determining the interannual variation of CO₂ uptake in this area.