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dc.contributor.authorLovenduski, Nicole S.  Concept link
dc.contributor.authorGruber, Nicolas  Concept link
dc.contributor.authorDoney, Scott C.  Concept link
dc.date.accessioned2010-05-07T14:55:54Z
dc.date.available2010-05-07T14:55:54Z
dc.date.issued2008-08-16
dc.identifier.citationGlobal Biogeochemical Cycles 22 (2008): GB3016en_US
dc.identifier.urihttps://hdl.handle.net/1912/3411
dc.descriptionAuthor Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 22 (2008): GB3016, doi:10.1029/2007GB003139.en_US
dc.description.abstractWe investigate the multidecadal and decadal trends in the flux of CO2 between the atmosphere and the Southern Ocean using output from hindcast simulations of an ocean circulation model with embedded biogeochemistry. The simulations are run with NCEP-1 forcing under both preindustrial and historical atmospheric CO2 concentrations so that we can separately analyze trends in the natural and anthropogenic CO2 fluxes. We find that the Southern Ocean (<35°S) CO2 sink has weakened by 0.1 Pg C a−1 from 1979–2004, relative to the expected sink from rising atmospheric CO2 and fixed physical climate. Although the magnitude of this trend is in agreement with prior studies (Le Quéré et al., 2007), its size may not be entirely robust because of uncertainties associated with the trend in the NCEP-1 atmospheric forcing. We attribute the weakening sink to an outgassing trend of natural CO2, driven by enhanced upwelling and equatorward transport of carbon-rich water, which are caused by a trend toward stronger and southward shifted winds over the Southern Ocean (associated with the positive trend in the Southern Annular Mode (SAM)). In contrast, the trend in the anthropogenic CO2 uptake is largely unaffected by the trend in the wind and ocean circulation. We regard this attribution of the trend as robust, and show that surface and interior ocean observations may help to solidify our findings. As coupled climate models consistently show a positive trend in the SAM in the coming century [e.g., Meehl et al., 2007], these mechanistic results are useful for projecting the future behavior of the Southern Ocean carbon sink.en_US
dc.description.sponsorshipThis work was supported by funding from various agencies. NSL was supported by NASA grant NNG05GP78H and the NOAA Climate and Global Change postdoctoral fellowship. NG was supported by NASA grant NNG04GH53G and by ETH Zurich. SCD was supported by NASA grant NNG05GG30G.en_US
dc.format.mimetypetext/plain
dc.format.mimetypeapplication/postscript
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.urihttps://doi.org/10.1029/2007GB003139
dc.subjectSouthern Oceanen_US
dc.subjectSouthern Annular Modeen_US
dc.subjectOcean carbon sinken_US
dc.titleToward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sinken_US
dc.typeArticleen_US
dc.identifier.doi10.1029/2007GB003139


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