Carbon dioxide variations in the Greenland Sea (scientific paper)

• Main Authors: Shuhji Aoki, Shinji Morimoto, Shuki Ushio, Hajime Ito, Takakiyo Nakazawa, Takashi Yamanouchi, Nobuo Ono, Torgny Vinge
• Format: Report
• Language: English
• Published: Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University/National Institute of Polar Research/National Institute of Polar Research/National Institute of Polar Research/Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University/National Institute of Polar Research/National Institute of Polar Research/Norwegian Polar Research Institute 1996
• Subjects: Greenland; Greenland Sea; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2292; http://id.nii.ac.jp/1291/00002292/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2292&item_no=1&attribute_id=18&file_no=1

pCO_2 in the surface layer of the Greenland Sea shows spatial and temporal variations. Lower values appear in the western and northern part of the sea in August, rising in value eastward and southward. The east-west gradient of pCO_2 is larger than the north-south gradient. A positive relationship between pCO_2 and sea surface temperature (SST) was observed in the open water region; the rate of change was 0.06℃^<-1>. This rate cannot be explained only by the temperature dependence of CO_2 solubility in sea water because the observed rate is higher than that of the pure temperature effect. No relationship between pCO_2 and SST was found in the pack ice region. pCO_2 in the surface layer of the Greenland Sea was higher in April, followed by a dramatic decrease in mid-May. These lower values of pCO_2 were observed until the end of August. pCO_2 in the ocean surface layer was always lower than that in the atmosphere from April to August. The difference of pCO_2 between the atmosphere and the ocean was about 40 μatm in April and reached a maximum of about 190 μatm in mid-May. Therefore, the Greenland Sea seems to act as a strong sink for atmospheric CO_2,especially in summer. ΣCO_2 and δ^<13>C were vertically and latitudinally uniform below 200m depth in the Greenland Sea in August. The uniformity suggests strong vertical mixing of sea water. The mean values of ΣCO_2 and δ^<13>C below 200m were 2.13 mmol kg^<-1> and 1.2‰ respectively. ΣCO_2 and δ^<13>C above 200m depth had a linear relationship with a coefficient of -10‰ (mmol (kg)^<-1>)^<-1>, suggesting ΣCO_2 decrease caused by strong biological activity.