[A-OS16] [EE] 地球規模環境変化に関する分野横断の海洋研究

[AOS16-08] Response of sea surface fugacity of CO₂ to the Southern Annular Mode (SAM) shift south of Tasmania

*Liang Xue¹、Libao Gao¹、Weidong Yu¹、Meng Wei¹ (1.FIO, SOA, China)

キーワード：Southern Ocean, Southern Annular Mode shift, Carbon cycling

Using observational data collected south of Tasmania during 14 austral summer cruises during 1993-2011, we examined the response of sea surface fugacity of carbon dioxide (fCO₂) to the Southern Annular Mode (SAM) shift, which occurred around 2000. In the southern part of the Southern Ocean (SO) or the Polar Zone (PZ) and the Polar Frontal Zone (PFZ), fCO₂ increased faster at the sea surface than in the atmosphere before the SAM shift, but not after the shift. In the northern part of the SO or the Sub-Antarctic Zone (SAZ), however, surface fCO₂ increased faster than atmospheric fCO₂ both before and after the shift. The SAM shift had an important influence on the surface fCO₂ trend in the PZ and PFZ, but not in the SAZ, which we attribute to differences in regional oceanographic processes (upwelling vs. non-upwelling). The SAM shift may have reversed the negative trend of SO CO₂ uptake.