References

BGD

Biogeosciences Discussions

BGD

1810-6285

Copernicus GmbH

Göttingen, Germany

10.5194/bgd-6-729-2009

Estimating the storage of anthropogenic carbon in the subtropical Indian Ocean: a comparison of five different approaches

Álvarez

¹ Lo Monaco

² Tanhua

³ Yool

⁴ Oschlies

³ Bullister

J. L.

⁵ Goyet

⁶ Metzl

² Touratier

⁶ McDonagh

⁴ Bryden

H. L.

⁴

IMEDEA (CSIC-UIB), Miquel Marqués 21, 07190 Esporles, Spain

LOCEAN/IPSL, Université Paris 6 – place Jussieu 4, 75252 Paris, France

IFM-GEOMAR, Düsternbrooker Weg 20, 24105 Kiel, Germany

NOCS, Waterfront Campus European Way, Southampton, SO14 3ZH, UK

NOAA/Pacific Marine Environmental Laboratory, Seattle, Washington, USA

IMAGES, Université de Perpignan, 52 avenue Paul Alduy, 66860 Perpignan, France

13 01 2009

6 1 729 796

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.biogeosciences-discuss.net/6/729/2009/bgd-6-729-2009.html

The full text article is available as a PDF file from http://www.biogeosciences-discuss.net/6/729/2009/bgd-6-729-2009.pdf

The subtropical Indian Ocean along 32° S was for the first time simultaneously sampled in 2002 for inorganic carbon and transient tracers. The vertical distribution and inventory of anthropogenic carbon (CANT) from five different methods: four data-base methods (ΔC*, TrOCA, TTD and C0IPSL and a simulation from the OCCAM model are compared and discussed along with the observed CFC-12 and CCl4 distributions. In the surface layer, where carbon-based methods are uncertain, TTD and OCCAM yield the same result (7±0.2 mol C m−2), helping to specify the surface CANT inventory. Below the mixed-layer, the comparison suggests that CANT penetrates deeper and more uniformly into the Antarctic Intermediate Water layer limit than estimated from the ΔC* method. Additionally, significant CFC-12 and CCl4 values are detected in bottom waters, associated with Antarctic Bottom Water. In this layer, except for ΔC* and OCCAM, the other methods detect significant CANT values. Consequently, the lowest inventory is calculated using the ΔC* method (24±2 mol C m−2) or OCCAM (24.4±2.8 mol C m−2) while TrOCA, TTD, and C0IPSL lead to higher inventories (28.1±2.2, 28.9±2.3 and 30.8±2.5 mol C m−2, respectively). Overall and despite the uncertainties each method is evaluated using its relationship with tracers and the knowledge about water masses in the subtropical Indian Ocean. Along 32° S our best estimate for the mean CANT specific inventory is 28±2 mol C m−2. Comparison exercises for data-based CANT methods along with time-series or repeat sections analysis should help to identify strengths and caveats in the CANT methods and to better constrain model simulations.

References 1

Álvarez, M., Ríos,~A F., Pérez,~F F., Rosón,~G., and Bryden,~H L.: Transports and budgets of total inorganic carbon in the subpolar and temperate North Atlantic, Glob.l Biogeochem. Cy., 17, 1002–1029, 2003.

Anderson,~L A.: On the hydrogen and oxygen content of marine phytoplankton, Deep-Sea Res. Pt I, 42, 1675–1680, 1995.

Anderson,~L G. and Sarmiento,~J L.: Redfield ratios of remineralization determined by nutrient data analysis, Glob. Biogeochem. Cy., 8, 65–80, 1994.

Bellerby,~R G J., Olsen,~A., Furevik,~T., and Anderson,~L A.: Response of the surface ocean \chemCO_2 system in the Nordic Seas and North Atlantic to climate change. In: Climate Variability in the Nordic Seas, ed. by Drange,~H., Dokken,~T M., Furevik,~T., Gerdes,~R., and Berger,~W., Geophysical Monograph Series, AGU, 189–198, 2005.

Benson,~B B. and Krause Jr.,~D.: The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere, Limnol. Oceanogr., 29, 620–632, 1984.

Bopp,~L., Monfray,~P., Aumont,~O., Dufresne,~J.-L., Treut,~H., Madec,~G., Terray,~L., and Orr,~J.: Potential impact of climate change on marine export production, Glob. Biogeochem. Cy., 15, 81–99, 2001.

Brea,~S., Álvarez-Salgado,~X A., Álvarez,~M., Pérez,~F F., Mémery,~L., Mercier,~H., and Messias,~M J.: Nutrient mineralization rates and ratios in the eastern South Atlantic, J Geophys. Res., 109, C05030, doi:10.1029/2003JC002051, 2004

Brewer,~P G., Bradshaw,~A., and Williams,~R.: Measurements of total carbon dioxide and alkalinity in the North Atlantic Ocean in 1981, in: The Changing Carbon Cycle, A~Global Analysis, edited by: Trabalka,~J. and Reichle,~D., Springer-Verlag, New York, 358–381, 1986.

Brewer,~P G.: Direct observations of the oceanic \chemCO_2 increase, Geophys. Res. Lett., 5, 997–1000, 1978.

Broecker,~W S.: \qutNO a~conservative water mass tracer, Earth Planet. Sc. Lett. 23, 8761–8776, 1974.

Broecker,~W S., Takahashi,~T., Simpson,~H J., and Peng,~T H.: Fate of fossil fuel carbon dioxide and the global carbon budget, Science, 206, 409–418, 1979.

Bryden, H. L., Cunningham, S., Benson, J., and Coauthors: RRS Charles Darwin Cruise 139, 01 Mar–15 Apr 2002; Trans-Indian hydrographic section across 32\unit\degree S. Southampton Oceanography Centre Cruise Rep. 45, 122 pp., 2003.

Bullister,~J L. and Wisegarver,~D.: The solubility of carbon tetrachloride in water and seawater, Deep-Sea Res. Pt I, 45, 1285–1302, 1998

Bullister,~J L. and Weiss,~R F.: Determination of CC13F and CC12F2 seawater and air, Deep-Sea Res., 25, 839-853, 1988.

Caldeira,~K. and Duffy,~P B.: The role of the southern ocean in uptake and storage of anthroprogenic carbon, Science, 287, 620–622, 2000.

Chen,~C.-T A.: The oceanic anthropogenic \chemCO_2 sink, Chemosphere, 27, 1041–1064, 1993.

Chen,~C T. and Millero,~F J.: Gradual increase of oceanic carbon dioxide, Nature, 277, 205–206, 1979.

Clayton,~T D. and Byrne,~R H.: Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale concentration scale calibration of m-cresol purple and at-sea results, Deep-Sea Res. Pt I, 40(10), 2115–2129, 1993.

Coatanoan,~C., Goyet,~C., Gruber,~N., Sabine,~C L., and Warner,~M.: Comparison of two approaches to quantify anthropogenic carbon in the ocean: results from the northern Indian ocean, Global Biogeochem. Cy., 15, 11–25, 2001.

Cole,~J J., Prairie,~Y T., Caraco,~N F., McDowell,~W H., Tranvik,~L J., Striegl,~R G., Duarte,~C M., Kortelainen,~P., Downing,~J A., Middleburg,~J., and Melack,~J.: Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget, Ecosystems, 10, 171–184, 2007.

Conkright,~M E., Antonov,~J I., Baranova,~O., Boyer,~T P., Garcia,~H E., Gelfeld,~R., Johnson,~D., Locarnini,~R A., Murphy,~P P., O'Brien,~T D., Smolyar,~I., and Stephens,~C.: NOAA Atlas NESDIS 42, WORLD OCEAN DATABASE 2001 Volume 1: Introduction,~US Gov. Printing Office, Wash.,~D C., 160 pp., 2002.

DelValls,~T A. and Dickson,~A G.: The pH of buffers based on 2-amino-2-hydroxymethyl-1,3-propanediol (\squttris) in synthetic sea water, Deep-Sea Res. Pt I, 45, 1541–1554, 1998.

Doney,~S C. and Bullister,~J L.: A~chlorofluorocarbon section in the eastern North Atlantic, Deep-Sea Res. Pt I, 39, 1857–1883, 1992.

Donohue,~K. and Toole,~J.: A~near-synoptic survey of the Southwest Indian Ocean, Deep-Sea Res., 50B, 1893–1931, 2003.

Duarte,~C M., Middelburg,~J J., and Caraco,~N.: Major role of marine vegetation on the oceanic carbon cycle, Biogeosciences, 2, 1–8, 2005.

Dutay, J.-C., Bullister, J. L., Doney, S. C., et al.: Evaluation of ocean model ventilation with CFC-11: comparison of 13 global ocean models, Ocean Model., 4, 89–120, 2002.

Feely,~R A., Sabine,~C L., Takahashi,~T., and Wanninkhof,~R.: Uptake and storage of carbon dioxide in the oceans: The global \chemCO_2 survey, Oceanography, 14, 18–32, 2001.

Fine,~R A., Smethie,~W M., Bullister, Jr J L., Rhein,~M., Min,~D.-H., Warner,~M J., Poisson,~A., and Weiss~R F.: Decadal ventilation and mixing of Indian Ocean waters, Deep-Sea Res. Pt I, 55, 20–37, 2008.

Fraga,~F., Ríos,~A F., Pérez,~F F., and Figueiras,~F G.: Theoretical limits of oxygen:carbon and oxygen:nitrogen ratios during photosynthesis and the mineralization of the organic matter in the sea, Sci. Mar., 62, 161–168, 1998.

Goyet,~C. and Brewer,~P G.: Biochemical properties of the oceanic carbon cycle, in: Modelling Oceanic Climate Interactions, edited by: Willebrand,~J. and Anderson,~D L T., NATO ASI Series, I 11, Springer, Berlin, Heidelberg, 271–297, 1993.

Goyet,~C., Coatanoan,~C., Eischeid,~G., Amaoka,~T., Okuda,~K., Healy,~R., and Tsunogai,~S.: Spatial variation of total alkalinity in the northern Indian Ocean: a~novel approach for the quantification of anthropogenic \chemCO_2 in seawater, J Mar. Res., 57, 135–163, 1999.

Gruber,~N., Sarmiento,~J L., and Stocker,~T F.: An improved method for detecting anthropogenic \chemCO_2 in the oceans, Global Biogeochem. Cy., 10, 809–837, 1996.

Gruber,~N.: Anthropogenic \chemCO_2 in the Atlantic Ocean, Global Biogeochem. Cy., 12, 165–191, 1998.

Haine,~T W N. and Hall,~T M.: A~generalized transport theory: water mass composition and age, J Phys. Oceanogr., 32, 1932–1946, 2002.

Hall~T M. and Primeau,~F W.: Separating the natural and anthropogenic air-sea flux of \chemCO_2: The Indian Ocean, Geophys. Res. Lett., 31, doi:10.1029/2004GL020589, 2004.

Hall,~T M., Haine,~T W N., and Waugh,~D W.: Inferring the concentration of anthropogenic carbon in the ocean from tracers, Glob. Biogeochem. Cy., 16, 1131, doi:10.1029/2001GB001835, 2002.

Hall,~T M., Waugh,~D W., Haine,~T W N., Robbins,~P E., and Khaliwala,~S.: Reduced estimates of anthropogenic carbon in the Indian ocean due to mixing and time-varying air-sea \chemCO_2 disequilibrium, Global Biogeochem. Cy., 18, GB1031, doi:10.1029/2003GB002120, 2004.

Hanawa,~K. and Talley,~L D.: Mode Waters, Ocean Circulation and Climate, edited by: Siedler,~G. and Church,~J., International Geophysics Series, Academic Press, 373–386, 2001.

Holfort,~J., Johnson,~K M., Scheider,~B., Siedler~G., and Wallace,~D W R.: Meridional transport of dissolved inorganic carbon in the South Atlantic Ocean, Glob. Biogeochem. Cy., 12, 479–499, 1998.

Hunh,~O., Roether,~W., Beining,~P., and Rose,~H.: Validity limits of carbon tetrachloride as an ocean tracer, Deep-Sea Res. Pt I, 48, 2025–2049, 2001.

IMBER report No 1, Joint SOLAS/IMBER Ocean Carbon Research Implementation Plan (http://www.imber.info/products/Carbon_Plan_final.pdf).

IPCC Report 2007 website: http://ipcc-wg1.ucar.edu/wg1/wg1-report.html

Jenkins,~W J.: \chem^3H and \chem^3He in the Beta triangle~: observations of gyre ventilation and oxygen utilization rates, J Phys. Oceangr., 17, 763–783, 1987.

Johnson~K M., Wills,~K D., Butler,~D B., Johnson,~W K., and Wong,~C S.: Coulometric total carbon dioxide analysis for marine studies: maximizing the performance of an automated gas extraction system and coulometric detector, Mar. Chem., 44, 167–188, 1993.

Karstensen,~J. and Quadfasel,~D.: Water subudcted into the Indian ocean subtropical gyre, Deep-Sea Res. Pt II, 49, 1441–1457, 2002.

Keeling,~C D. and Whorf~T P.: Atmospheric \chemCO_2 Records from Sites in the SIO Air Sampling Network. in: Trends: A~Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U S. Department of Energy, Oak Ridge, Tenn., USA, 2005.

Key,~R M., Kozyr,~A., Sabine,~C L., Lee,~K., Wanninkhof,~R., Bullister,~J L., Feely,~R A., Millero,~F J., Mordy,~C., and Peng,~T.-H.: A~global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP), Glob. Biogeochem. Cy., 18, GB4031, doi:10.1029/2004GB002247, 2004.

Key,~R M., Kozyr,~A., Sabine,~C L., Lee,~K., Wanninkhof,~R., Bullister,~J., Feely,~R A., Millero,~F., Mordy,~C., and Peng,~T.-H.: A~global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP), Global Biogeochem. Cy., 18, GB4031, doi:10.1029/2004GB002247, 2004.

Kirkwood,~D S.: Nutrients: Practical notes on their determination in seawater. ICES Techniques in Marine Environmental Sciences report 17, International Council for the Exploration of the Seas, Copenhagen, 25 p., ISSN 0903-2606, 1995

Körtzinger,~A., Mintrop,~L., and Duinker,~J C.: On the penetration of anthropogenic \chemCO_2 into the North Atlantic Ocean, J Geophys. Res., 103, 18 681–18 689, 1998.

Körtzinger,~A., Hedges,~J I., and Quay,~P D.: Redfield ratios revisited: Removing the biasing effect of anthropogenic \chemCO_2, Limnol. Oceanogr., 46, 964–970, 2001.

Lamb,~M F., Sabine,~C L., Feely,~R A., Wanninkhof,~R., Key,~R M., Johnson,~G C., Millero,~F J., Lee,~K., Peng,~T.-H., Kozyr,~A., Bullister,~J L., Greeley,~D., Byrne,~R H., Chipman,~D W., Dickson,~A G., Goyet,~C., Guenther,~P R., Ishii,~M., Johnson,~K M., Keeling,~C D., Ono,~T., Shitashima,~K., Tilbrook,~B., Ono,~T., Takahashi,~R., Wallace,~D W R., Watanabe,~Y., Winn,~C., and Wong,~C S : Consistency and synthesis of Pacific Ocean \chemCO_2 survey data, Deep-Sea Res. Pt II, 49, 21–58, 2002.

Large,~W. and Yeager,~S.: Diurnal to decadal global forcing for ocean and sea-ice models: the data sets and flux climatologies. CGD Division of the National Center for Atmospheric Research, NCAR Technical Note: NCAR/TN-460+STR, 2004.

Laws,~E A.: Photosynthetic quotients, new production and net community production in the open ocean, Deep-Sea Res., 38, 143–167, 1991.

Levitus, S., Antonov, J. I., Wang, J., et al.: Anthropogenic warming of the earth's climate system, Science, 292, 267–270, 2001.

Lo Monaco,~C., Metzl,~N., Poisson,~A., Brunet,~C., and Schauer,~B.: Anthropogenic \chemCO_2 in the Southern Ocean: Distribution and inventory at the Indian-Atlantic boundary (World Ocean Circulation Experiment line I6), J Geophys. Res., 110, C09S02, doi:10.1029/2004JC002643, 2005b.

Lo Monaco~C., Goyet,~C., Metzl,~N., Poisson,~A., and Touratier,~F.: Distribution and inventory of anthropogenic \chemCO_2 in the Southern Ocean: comparison of three data-based methods, J Geophys. Res., 110, doi:10.1029/2004JC002571, 2005a.

Lueker,~T J., Dickson,~A G., and Keeling,~C D.: Ocean p\chemCO_2 calculated from dissolved inorganic carbon, alkalinity and equations for K1 and K2: validations based on laboratory measurements of \chemCO_2 in gas and seawater at equilibrium, Mar. Chem., 70, 105–119, 2000.

Hoppema,~M., Roether,~W., Bellerby,~R G J., and De Baar,~H J W.: Direct measurements reveal insignificant storage of anthropogenic \chemCO_2 in the abyssal Weddell Sea, Geophys. Res. Lett., 28, 1747–1750, 2001.

Marsh,~R., de Cuevas,~B A., Coward,~A C., Bryden,~H L., and Alvarez,~M.: Thermohaline circulation at three key sections of the North Atlantic over 1985–2002, Geophys. Res. Lett. 32, L10604, doi:10.1029/2004GL022281, 2005.

Matear~R J., Wong,~C S., and Xie,~L.: Can CFCs be used to determine anthropogenic \chemCO_2?, Global Biogeochem. Cy., 17, 1013, doi:10.1029/2001GB001415, 2003.

Matsumoto,~K. and Gruber,~N.: How accurate is the estimation of anthropogenic carbon in the ocean? An evaluation of the $\Delta $C* method, Glob. Biogeochem. Cy., 19, GB3014, doi:10.1029/2004GB002397, 2005.

Matsumoto, K., Sarmiento, J. L., Key, J. M., et al.: Evaluation of ocean carbon cycle models with data-based metrics, Geophys. Res. Lett., 31, L07303, doi:10.1079/2003GL018970, 2004.

McCartney,~M.: Subantartctic mode water, in: a~voyage of discovery, Deep-Sea Res., 24, 103–119, 1977.

McDonagh,~E L., Bryden,~H L., King,~B A., Sanders,~R J., Cunningham,~S A., and Marsh, R: Decadal changes in the south Indian ocean, J Climate, 18, 1575–1590, 2005.

McDonagh, E. L., Bryden, H. L., King, B. A., and Sanders, R. J.: The circulation of the Indian Ocean at 32° S, Progr. Ocean., 79, 20–36, 2008.

McNeil~B I., Metzl,~N., Key,~R M., Matear,~R J., and Corbiere,~A.: An empirical estimate of the Southern Ocean air-sea \chemCO_2 flux, Global Biogeochem. Cy., 21, GB3011, doi:10.1029/2007GB002991, 2007.

Mecking,~S. and Warner,~M J.: Ventilation of Red Sea Water with respect to chlorofluorocarbons, J Geophys. Res., 104, 11087–11097, 1999.

Meredith,~M P., Watson,~A J., Van Scoy,~K A., and Haine,~T W N.: Chlorofluorocarbon-derived formation rates of the deep and bottom waters of the Weddell Sea, J Geophys. Res., 106, 2899–2919, 2001.

Metzl,~N., Brunet,~C., Jabaud-Jan,~A., Poisson,~A., and Schauer,~B.: Summer and winter air–sea \chemCO_2 fluxes in the Southern Ocean, Deep-Sea Res. Pt I, 53, 1548–1563, 2006.

Mikaloff Fletcher S. E., Gruber, N., Jacobson, A. R., et al. Inverse estimates of anthropogenic \chemCO_2 uptake, transport, and storage by the ocean, Glob. Biogeochem. Cy., 20, GB2002, doi:10.1029/2005GB002530, 2006.

Millero,~F.: The marine inorganic carbon cycle, Chem. Rev., 107, 308–341, 2007.

Murata,~A., Kumamoto,~Y., Sasaki,~K., Watanabe,~S., and Fukasawa,~M.: Decadal increases of anthropogenic CO2 in the subtropical South Atlantic Ocean along 30$_$S, J Geophys. Res., 113, C06007, doi:10.1029/2007JC004424, 2008.

Orr,~J E., Fabry,~V J., Aumont,~O., Bopp,~L., Doney,~S C., Feely,~R A., et al.: Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms, Nature, 437, 681–686, 2005.

Orr,~J E., Maier-Reimer,~E., Mikolajewicz,~U., Monfray~P., Sarmiento,~J L., Toggweiler,~J R., Taylor,~N K., Palmer,~J. Gruber,~N., Sabine,~C L. LeQuéré,~C., Key,~R M., and Boutin,~J.: Estimates of anthropogenic carbon uptake from four three-dimensional global ocean models, Glob. Biogeochem. Cy., 15, 43–60, 2001.

Orsi, A. H., Smethie Jr., W. M., and Bullister, J. L.: On the total input of Antarctic waters to the deep ocean: A preliminary estimate from chlorofluorocarbon measurements, J. Geophys. Res., 107, 3122, doi:10.1029/2001JC000976, 2002.

Orsi,~A H., Johnson,~G C., and Bullister,~J L.: Circulation, mixing and production of Antarctic Bottom Water, Prog. Oceanogr., 43, 55–109, 1999.

Oschlies,~A.: Model-derived estimates of new production: New results point towards lower values. Deep–Sea Res. II, 48, 2173–2197, 2001.

Papaud~A. and Poisson,~A.: Distribution of dissolved \chemCO_2 in the Red Sea and correlation with other geochemical tracers, J Mar. Res., 44, 385–402, 1986.

Pérez,~F F., Álvarez,~M., and Ríos,~A F.: Improvements on the back-calculation technique for estimating anthropogenic \chemCO_2, Deep-Sea Res. Pt I, 49, 859–875, 2002.

Pérez,~F F. and Fraga,~F.: A~precise and rapid analytical procedure for alkalinity determination, Mar. Chem., 21, 169–182, 1987.

Pérez,~F F., Ríos,~A F., Rellán,~T., and Álvarez,~M.: Improvements in a~fast potentiometric seawater alkalinity determination, Cienc. Mar., 26, 463–478, 2000.

Poisson,~A. and Chen,~C.-T A.: Why is there little anthropogenic \chemCO_2 in the Antarctic Bottom Water?, Deep-Sea Res., 34, 1255–1275, 1987.

Prairie,~Y T. and Duarte,~C M.: Direct and indirect metabolic \chemCO_2 release by humanity, Biogeosciences, 4, 215–217, 2007.

Sabine,~C L., Key,~R M., Johnson,~K M. , Millero,~F J., Poisson,~A., Sarmiento,~J L., Wallace,~D W R., and Winn,~C D.: Anthropogenic \chemCO_2 inventory of the Indian Ocean, Glob. Biogeochem. Cy., 13, 179–198, 1999.

Sabine,~C. and Feely,~R.: Comparison of recent Indian Ocean anthropogenic \chemCO_2 estimates with a~historical approach, Glob. Biogeochem. Cy., 15, 31–42, 2001.

Sabine, C. and Feely, R. A.: The oceanic sink for anthropogenic \chemCO_2, Science, 305, 367–371, 2004.

Sallée,~J B., Wienders,~N., Morrow,~R., and Speer,~K.: Formation of subantarctic mode water in the southeastern Indian Ocean, Ocean Dynam., 56, 525–542, 2006.

Sandrini,~S., Ait-Ameur,~N., Rivaro,~P., Massolo,~S., Touratier,~F., Tositti,~L., and Goyet,~C.: Anthropogenic carbon distribution in the Ross Sea, Antarctica, Antarct. Sci., 19, 395–407, 2007.

Sarma,~V V S S., Ono,~T., and Saino,~T.: Increase of total alkalinity due to shoaling of aragonite saturation horizon in the Pacific and Indian Oceans: Influence of anthropogenic carbon inputs, Geophys. Res. Lett., 29(20), 1971, doi:10.1029/ 2002GL015135, 2002.

Sloyan ,~B M. and Rintoul,~S R.: Circulation, renewal, and modification of Antarctic mode and intermediate water, J Phys. Oceanogr., 31, 1005–1030, 2001.

Takahashi,~T., Sutherland,~S C., Sweeney,~C., Poisson,~A., Metzl,~N., Tillbrook,~B., Bates,~N., Wanninkhof,~R., Feely,~R A., Sabine,~C., Olafsson,~J., and Nojiri,~Y.: Global sea-air \chemCO_2 flux based on climatological surface ocean p\chemCO_2, and seasonal biological and temperature effects, Deep-Sea Res. Pt II, 49, 1601–1622, 2002.

Talley,~L D.: Antarctic Intermediate Water in the South Atlantic, The South Atlantic: Present and Past Circulation, edited by Wefer,~G., Berger,~W H., Siedler,~G., and Webb,~D., Springer-Verlag, 219–238, 1996.

Tanhua,~T., Waugh,~D W., and Wallace,~D W R.: Use of SF$_6$ to Estimate Anthropogenic \chemCO_2 in the Upper Ocean, J Geophys. Res., 113, C04037, doi:10.1029/2007JC004416.

Touratier,~F. and Goyet,~C.: Definition, properties, and Atlantic distribution of the new tracer TrOCA, J Marine Syst., 46, 169–179, 2004a.

Touratier,~F. and Goyet,~C.: Applying the new TrOCA approach to assess the distribution of anthropogenic \chemCO_2 in the Atlantic Ocean, J Marine Syst., 46, 181–197, 2004b.

Touratier,~F., Azouzi,~L., and Goyet,~C.: CFC-11, $\Delta ^14$C and \chem^3H tracers as a~means to assess anthropogenic \chemCO_2 concentrations in the ocean, Tellus, 59B, 318–325, 2007.

Vázquez-Rodríguez,~M., Touratier,~F., Lo Monaco,~C., Waugh,~D W., Padín,~X A., Bellerby,~R G J., Goyet,~C., Metzl,~N., Ríos,~A F., and Pérez~F F.: Anthropogenic carbon distributions in the Atlantic Ocean: data-based estimates from the Arctic to the Antarctic, Biogeosciences Discuss., 5, 1421–1443, 2008.

Walker,~S J., Weiss,~R F., and Salameh P K.: Reconstructed histories of the annual mean atmospheric mole fractions for the halocarbons CFC-11, CFC-12, CFC-113 and carbon tetrachloride, J Geophys. Res., 105, 14285–14296, 2000.

100

Wallace,~D W R.: Storage and Transport of Excess \chemCO_2 in the Oceans: The JGOFS/WOCE Global \chemCO_2 Survey, in: Ocean Circulation and Climate, International Geophysics Series, vol 77, edited by: Siedler,~G., Church,~J., and Gould,~J., Academic Press, 489–520, 2001.

101

Wanninkhof,~R., Peng,~T.-H., Sabine,~C L., and Lee,~K.: Comparison of Inorganic Carbon System Parameters Measured in the Atlantic Ocean from 1990 to 1998 and Recommended Adjustments ORNL/CDIAC-140, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory,~US Department of Energy, Oak Ridge, TN, 43 pp., 2003.

102

Wanninkhof,~R., Doney,~S C., Peng,~T H., Bullister,~J L., Lee,~K., and Feely,~R A.: Comparison of methods to determine the anthropogenic \chemCO_2 invasion into the Atlantic Ocean, Tellus, 51B, 511–530, 1999.

103

Warner,~M. and Weiss,~R.: Solubilities of chorofluorocarbons 11 and 12 in water and seawater, Deep-Sea Res., 32, 1485–1497, 1985.

104

Waugh,~D W., Haine,~T W N., and Hall,~T M.: Transport times and anthropogenic carbon in the subpolar North Atlantic Ocean, Deep-Sea Res. Pt I, 51, 1475–1491, 2004.

105

Waugh,~D W., Hall,~T M., McNeil,~B I., Key,~R., and Matear,~R J.: Anthropogenic \chemCO_2 in the oceans estimated sing transit time distributions, Tellus, 58B, 376–389, 2006.

106

Weppernig,~R., Schlosser,~P., Khatiwala,~S., and Fairbanks,~R G.: Isotope data from Ice Station Weddell: Implications for deep water formation in the Weddell Sea, J Geophys. Res., 101, 25 723–25 739, 1996.

107

Wetzel~P.,~A. Winguth,~A., and Maier-Reimer,~E.: Sea-to-air \chemCO_2 flux from 1948 to 2003: A~model study, Glob. Biogeochem. Cy., 19, GB2005, doi:10.1029/2004GB002339, 2005.

108

Yool,~A., Martin,~A P., Fernandez,~C., and Clark,~D R.: The significance of nitrification for oceanic new production, Nature, 447, 999–1002, doi:10.1038/nature05885, 2007.