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

Authors: NAKAOKA, SHIN-ICHIRO; AOKI, SHUJI¹; NAKAZAWA, TAKAKIYO¹; HASHIDA, GEN²; MORIMOTO, SHINJI²; YAMANOUCHI, TAKASHI²; YOSHIKAWA-INOUE, HISAYUKI³

Source: Tellus B, Volume 58, Number 2, April 2006 , pp. 148-161(14)

Publisher: Wiley-Blackwell

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Abstract:

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 yr⁻¹) 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 m⁻² yr⁻¹ in the Greenland Sea and 46 ± 18 gC m⁻² yr⁻¹ 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.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0889.2006.00178.x

Affiliations: 1: Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University, Sendai 980–8578, Japan 2: National Institute of Polar Research, Tokyo 173–8515, Japan 3: Laboratory of Marine and Atmospheric Geochemistry, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060–0808, Japan

Publication date: 2006-04-01