Seasonally different carbon flux changes in the Southern Ocean in response to the southern annular mode
Article first published online: 5 DEC 2013
© 2013 The Authors. Global Biogeochemical Cycles published byWiley on behalf of the American Geophysical Union.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Global Biogeochemical Cycles
Volume 27, Issue 4, pages 1236–1245, December 2013
How to Cite
2013), Seasonally different carbon flux changes in the Southern Ocean in response to the southern annular mode, Global Biogeochem. Cycles, 27, 1236-1245, doi:10.1002/2013GB004600., , , , , and (
- Issue published online: 16 JAN 2014
- Article first published online: 5 DEC 2013
- Accepted manuscript online: 13 NOV 2013 10:50PM EST
- Manuscript Accepted: 10 NOV 2013
- Manuscript Revised: 30 OCT 2013
- Manuscript Received: 22 MAR 2013
- Southern Ocean;
- southern annular mode;
- carbon cycle;
- carbon sink
 Stratospheric ozone depletion and emission of greenhouse gases lead to a trend of the southern annular mode (SAM) toward its high-index polarity. The positive phase of the SAM is characterized by stronger than usual westerly winds that induce changes in the physical carbon transport. Changes in the natural carbon budget of the upper 100 m of the Southern Ocean in response to a positive SAM phase are explored with a coupled ecosystem-general circulation model and regression analysis. Previously overlooked processes that are important for the upper ocean carbon budget during a positive SAM period are identified, namely, export production and downward transport of carbon north of the polar front (PF) as large as the upwelling in the south. The limiting micronutrient iron is brought into the surface layer by upwelling and stimulates phytoplankton growth and export production but only in summer. This leads to a drawdown of carbon and less summertime outgassing (or more uptake) of natural CO2. In winter, biological mechanisms are inactive, and the surface ocean equilibrates with the atmosphere by releasing CO2. In the annual mean, the upper ocean region south of the PF loses more carbon by additional export production than by the release of CO2 into the atmosphere, highlighting the role of the biological carbon pump in response to a positive SAM event.