Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009
| Type | Article | ||||||||
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| Date | 2013 | ||||||||
| Language | English | ||||||||
| Author(s) | Lenton A.1, Tilbrook B.1, 2, Law R. M.3, Bakker D.4, Doney S. C.5, Gruber N.6, 7, Ishii M.8, Hoppema M.9, Lovenduski N. S.10, Matear R. J.11, McNeil B. I.12, Metzl N.13, Mikaloff Fletcher S. E.14, Monteiro P. M. S.15, 16, Roedenbeck C.17, Sweeney C.18, Takahashi T.19 | ||||||||
| Affiliation(s) | 1 : CSIRO Marine & Atmospher Res, Ctr Australian Weather & Climate Res, Hobart, Tas, Australia. 2 : Antarctic Climate Ecosyst Cooperat Res Ctr, Hobart, Tas, Australia. 3 : CSIRO Marine & Atmospher Res, Ctr Australian Weather & Climate Res, Aspendale, Vic, Australia. 4 : Univ East Anglia Res Pk, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England. 5 : Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543 USA. 6 : ETH, Inst Biogeochem & Pollutant Dynam, Zurich, Switzerland. 7 : ETH, Ctr Climate Syst Modeling, Zurich, Switzerland. 8 : Meteorol Res Inst, Tsukuba, Ibaraki 3050031, Japan. 9 : Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany. 10 : Univ Colorado, Inst Arctic & Alpine Res, Dept Atmospher & Ocean Sci, Boulder, CO 80309 USA. 11 : CSIRO Marine & Atmospher Res, Ctr Australian Weather & Climate Res, Hobart, Tas, Australia. 12 : Univ New S Wales, Climate Change Res Ctr, Sydney, NSW, Australia. 13 : Univ Paris 06, CNRS, LOCEAN IPSL, Lab Oceanog & Climat, Paris, France. 14 : Natl Inst Water & Atmospher Res, Wellington 6021, New Zealand. 15 : Univ Cape Town, Dept Oceanog, ZA-7700 Rondebosch, South Africa. 16 : CSIR, Ocean Syst & Climate Grp, Stellenbosch, South Africa. 17 : Max Planck Inst Biogeochem, D-07745 Jena, Germany. 18 : Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80305 USA. 19 : Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY USA. |
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| Source | Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2013 , Vol. 10 , N. 6 , P. 4037-4054 | ||||||||
| DOI | 10.5194/bg-10-4037-2013 | ||||||||
| WOS© Times Cited | 154 | ||||||||
| Abstract | The Southern Ocean (44-75 degrees S) plays a critical role in the global carbon cycle, yet remains one of the most poorly sampled ocean regions. Different approaches have been used to estimate sea-air CO2 fluxes in this region: synthesis of surface ocean observations, ocean biogeochemical models, and atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Southern Ocean sea-air CO2 fluxes between 1990-2009. Using all models and inversions (26), the integrated median annual sea-air CO2 flux of -0.42+/-0.07 Pg C yr(-1) for the 44-75 degrees S region, is consistent with the -0.27+/-0.13 Pg C yr(-1) calculated using surface observations. The circumpolar region south of 58 degrees S has a small net annual flux (model and inversion median: -0.04+/-0.07 Pg C yr(-1) and observations: +0.04+/-0.02 Pg C yr(-1)), with most of the net annual flux located in the 44 to 58 degrees S circumpolar band (model and inversion median: -0.36+/-0.09 Pg C yr(-1) and observations: -0.35+/-0.09 Pg C yr(-1)). Seasonally, in the 44-58 degrees S region, the median of 5 ocean biogeochemical models captures the observed sea-air CO2 flux seasonal cycle, while the median of 11 atmospheric inversions shows little seasonal change in the net flux. South of 58 degrees S, neither atmospheric inversions nor ocean biogeochemical models reproduce the phase and amplitude of the observed seasonal sea-air CO2 flux, particularly in the Austral Winter. Importantly, no individual atmospheric inversion or ocean biogeochemical model is capable of reproducing both the observed annual mean uptake and the observed seasonal cycle. This raises concerns about projecting future changes in Southern Ocean CO2 fluxes. The median interannual variability from atmospheric inversions and ocean biogeochemical models is substantial in the Southern Ocean; up to 25% of the annual mean flux, with 25% of this interannual variability attributed to the region south of 58 degrees S. Resolving long-term trends is difficult due to the large interannual variability and short time frame (1990-2009) of this study; this is particularly evident from the large spread in trends from inversions and ocean biogeochemical models. Nevertheless, in the period 1990-2009 ocean biogeochemical models do show increasing oceanic uptake consistent with the expected increase of -0.05 Pg C yr(-1) decade(-1). In contrast, atmospheric inversions suggest little change in the strength of the CO2 sink broadly consistent with the results of Le Quere et al. (2007). | ||||||||
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