Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 11, 4077-4098, 2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
01 Aug 2014
Strong sensitivity of Southern Ocean carbon uptake and nutrient cycling to wind stirring
K. B. Rodgers1, O. Aumont2, S. E. Mikaloff Fletcher3, Y. Plancherel4, L. Bopp5, C. de Boyer Montégut6, D. Iudicone7, R. F. Keeling8, G. Madec9,10, and R. Wanninkhof11 1AOS Program, Princeton University, Princeton, NJ, USA
2IRD, Plouzané, France
3NIWA, Wellington, New Zealand
4Department of Earth Sciences, University of Oxford, Oxford, UK
5LSCE, IPSL, CNRS, CEA, UVSQ, Gif-sur-Yvette, France
6IFREMER, Centre de Brest, Laboratoire d'Océanographie Spatiale, Plouzané, France
7Stazione Zoologica Anton Dohrn, Naples, Italy
8Scripps Institute of Oceanography, UCSD, San Diego, CA, USA
10National Oceanography Centre, Southampton, UK
Abstract. Here we test the hypothesis that winds have an important role in determining the rate of exchange of CO2 between the atmosphere and ocean through wind stirring over the Southern Ocean. This is tested with a sensitivity study using an ad hoc parameterization of wind stirring in an ocean carbon cycle model, where the objective is to identify the way in which perturbations to the vertical density structure of the planetary boundary in the ocean impacts the carbon cycle and ocean biogeochemistry.

Wind stirring leads to reduced uptake of CO2 by the Southern Ocean over the period 2000–2006, with a relative reduction with wind stirring on the order of 0.9 Pg C yr−1 over the region south of 45° S. This impacts not only the mean carbon uptake, but also the phasing of the seasonal cycle of carbon and other ocean biogeochemical tracers. Enhanced wind stirring delays the seasonal onset of stratification, and this has large impacts on both entrainment and the biological pump. It is also found that there is a strong reduction on the order of 25–30% in the concentrations of NO3 exported in Subantarctic Mode Water (SAMW) to wind stirring. This finds expression not only locally over the Southern Ocean, but also over larger scales through the impact on advected nutrients. In summary, the large sensitivity identified with the ad hoc wind stirring parameterization offers support for the importance of wind stirring for global ocean biogeochemistry through its impact over the Southern Ocean.

Citation: Rodgers, K. B., Aumont, O., Mikaloff Fletcher, S. E., Plancherel, Y., Bopp, L., de Boyer Montégut, C., Iudicone, D., Keeling, R. F., Madec, G., and Wanninkhof, R.: Strong sensitivity of Southern Ocean carbon uptake and nutrient cycling to wind stirring, Biogeosciences, 11, 4077-4098, doi:10.5194/bg-11-4077-2014, 2014.
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