A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

Biogeosciences

Volumn 10, Issue 11, 2013, Pages 7793-7815

  Landschutzer P ^a   Gruber, N ^b   Bakker, D C E ^a   Schuster, U ^a,f   Nakaoka, S ^c   Payne, M R ^b,d   Sasse, T P ^e   Zeng, J ^c  

^a UNIVERSITY OF EAST ANGLIA   (United Kingdom)

^b ETH ZURICH   (Switzerland)

^c NATIONAL INSTITUTE FOR ENVIRONMENTAL STUDIES   (Japan)

^d TECHNICAL UNIVERSITY OF DENMARK   (Denmark)

^e UNIVERSITY OF NEW SOUTH WALES   (Australia)

^f UNIVERSITY OF EXETER   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

AIR-SEA INTERACTION; ANNUAL VARIATION; ARTIFICIAL NEURAL NETWORK; BIOGEOCHEMISTRY; CARBON DIOXIDE; CARBON SINK; DATABASE; GAS FLOW; PARAMETERIZATION; PARTIAL PRESSURE; SEASONAL VARIATION; TIME SERIES;

ATLANTIC OCEAN;

EID: 84889840127     PISSN: 17264170     EISSN: 17264189     Source Type: Journal    
DOI: 10.5194/bg-10-7793-2013     Document Type: Article

References (71)

1. Amari, S., Murata, N., Müller, K.-R., Finke, M., and Yang, H. H.: Asymptotic Statistical Theory of Overtraining and Cross- Validation, IEEE T. Neural Networ., 8, 985-996, 1997. (Pubitemid 127763330)
2. Antonov, J. I., Seidov, D., Boyer, T. P., Locarnini, R. A., Mishonov, A. V., and Garcia, H. E.: World Ocean Atlas 2009, Volume 2: Salinity, NOAA Atlas NESDIS 69, U.S. Government Printing Office, Washington, DC, 2010.
3. Atlas, R., Hoffman, R. N., Ardizzone, J., Leidner, S. M., Jusem, J. C., Smith, D. K., and Gombos, D.: A cross-calibrated multiplatform ocean surface wind velocity product for meteorological and oceanographic applications, B. Am. Meteorol. Soc., 92, 157-174, 2011.
4. Bakker, D. C. E., Pfeil, B., Smith, K., Hankin, S., Olsen, A., Alin, S. R., Cosca, C., Harasawa, S., Kozyr, A., Nojiri, Y., O'Brien, K. M., Schuster, U., Telszewski, M., Tilbrook, B., Wada, C., Akl, J., Barbero, L., Bates, N., Boutin, J., Cai, W.-J., Castle, R. D., Chavez, F. P., Chen, L., Chierici, M., Currie, K., de Baar, H. J. W., Evans, W., Feely, R. A., Fransson, A., Gao, Z., Hales, B., Hardman-Mountford, N., Hoppema, M., Huang, W.-J., Hunt, C. W., Huss, B., Ichikawa, T., Johannessen, T., Jones, E. M., Jones, S. D., Jutterström, S., Kitidis, V., Körtzinger, A., Landschtzer, P., Lauvset, S. K., Lefèvre, N., Manke, A. B., Mathis, J. T., Merlivat, L., Metzl, N., Murata, A., Newberger, T., Ono, T., Park, G.-H., Paterson, K., Pierrot, D., Ríos, A. F., Sabine, C. L., Saito, S., Salisbury, J., Sarma, V. V. S. S., Schlitzer, R., Sieger, R., Skjelvan, I., Steinhoff, T., Sullivan, K., Sun, H., Sutton, A. J., Suzuki, T., Sweeney, C., Takahashi, T., Tjiputra, J., Tsurushima, N., van Heuven, S. M. A. C., Vandemark, D., Vlahos, P., Wallace, D. W. R., Wanninkhof, R., and Watson, A. J.: An update to the Surface Ocean CO2 Atlas (SOCAT version 2), Earth Syst. Sci. Data Discuss., 6, 465-512, doi:10.5194/essdd-6-465-2013, 2013.
5. Bates, N. R.: Interannual variability of the oceanic CO2 sink in the subtropical gyre of the North Atlantic Ocean over the last 2 decades, J. Geophys. Res., 112, C09013, doi:10.1029/2006JC003759, 2007. (Pubitemid 350120732)
6. Bennington, V., McKinley, G. A., Dutkiewicz, S., and Ullman, D.: What does chlorophyll variability tell us about export and air-sea CO2 flux variability in the North Atlantic?, Global Biogeochem. Cy., 23, GB3002, doi:10.1029/2008GB003241, 2009.
7. Carton, J. A. and Giese, B. S.: A Reanalysis of Ocean Climate Using Simple Ocean Data Assimilation (SODA), Mon. Weather Rev., 136, 2999-3017, doi:10.1175/2007MWR1978.1, 2008.
8. Chierici, M., Olsen, A., Johannessen, T., Trinañes, J., and Wanninkhof, R.: Algorithms to estimate the carbon dioxide uptake in the northern North Atlantic using ship board observations, satellite and ocean analysis data, Deep-Sea Res. Pt. II, 56, 630-639, 2009.
9. Corbière, A., Metzl, N., Reverdin, G., Brunet, C., and Takahashi, T.: Interannual and decadal variability of the oceanic carbon sink in the North Atlantic subpolar gyre, Tellus, 59B, 168-178, 2007. (Pubitemid 46455923)
10. de Boyer Montegut, C., Madec, G., Fischer, A. S., Lazar, A., and Iudicone, D.: Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology, J. Geophys. Res., 109, C12003, doi:10.1029/2004JC002378, 2004. (Pubitemid 40335109)
11. Demuth, H., Beale, M., and Hagan, M.: Neural Network Toolbox 6 Users Guide, The MathWorks, Inc., 3 Apple Hill Drive, Natick, MA, 2008.
12. Dickson, A. G., Sabine, C. L., and Christian, J. R., (Eds.): Guide to Best Practices for Ocean CO2 Measurements, PICES Special Publication, IOCCP Report No. 8, 2007.
13. Doney, S., Fabry, V., Feely, R. A., and Kleypas, J.: Ocean Acidification: The Other CO2 Problem, Annu. Rev. Mar. Sci., 1, 169-192, doi:10.1146/annurev. marine.010908.163834, 2009.
14. Fay, A. R. and McKinley, G. A.: Global trends in surface ocean pCO2 from in situ data, Global Biogeochem. Cy., 27, 1-17, doi:10.1002/gbc.20051, 2013.
15. Friedrich, T. and Oschlies, A.: Neural network-based estimates of North Atlantic surface pCO2 from satellite data: A methodological study, J. Geophys. Res., 114, C03020, doi:10.1029/2007JC004646, 2009.
16. GLOBALVIEW-CO2: Cooperative Atmospheric Data Integration Project - Carbon Dioxide, CD-ROM, NOAA ESRL, Boulder, Colorado [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/co2/GLOBALVIEW], 2011.
17. González-Dávila, M., Santana-Casiano, J. M., and González- Dávila, E. F.: Interannual variability of the upper ocean carbon cycle in the Northeast Atlantic Ocean, Geophys. Res. Lett., 34, L07608, doi:10.1029/2006GL028145, 2007. (Pubitemid 46957887)
18. Graven, H. D., Guilderson, T., and Keeling, R.: Observations of radiocarbon in CO2 at seven global sampling sites in the Scripps flask network: Analysis of spatial gradients and seasonal cycles, J. Geophys. Res., 117, D02303, doi:10.1029/2011JD016533, 2012.
19. Gruber, N.: Fickle trends in the ocean, Nature, 458, 155-156, 2009.
20. Gruber, N., Keeling, C. D., and Bates, N. R.: Interannual Variability in the North Atlantic Ocean Carbon Sink, Science, 298, 2374- 2378, doi:10.1126/science.1077077, 2002. (Pubitemid 36014207)
21. Gruber, N., Gloor, M., Mikaloff Fletcher, S. E., Doney, S. C., Dutkiewicz, S., Follows, M. J., Gerber, M., Jacobson, A. R., Joos, F., Lindsay, K., Menemenlis, D., Mouchet, A., Müller, S. A., Sarmiento, J. L., and Takahashi, T.: Oceanic sources, sinks, and transport of atmospheric CO2, Global Biogeochem. Cy., 23, GB1005, doi:10.1029/2008GB003349, 2009.
22. Gurney, K., Baker, D., Rayner, P., and Denning, S.: Interannual variations in continental-scale net carbon exchange and sensitivity to observing networks estimated from atmospheric CO2 inversions for the period 1980 to 2005, Global Biogeochem. Cy., 22, GB3025, doi:10.1029/2007GB003082, 2008.
23. Hagan, M., Demuth, H. B., and Beale, M. H.: Neural Network Design, PWS Publishing, Boston, MA, 1996.
24. Hagan, M. T. and Menhaj, M.: Training feed-forward networks with the Marquardt algorithm, IEEE T. Neural Networ., 5, 989-993, 1994.
25. Hurrell, J. W.: Decadal trends in the North-Atlantic Oscillation: regional temperatures and precipitation, Science, 269, 676-679, 1995. (Pubitemid 26439360)
26. Jones, S. D., Le Quéré, C., and Rödenbeck, C.: Autocorrelation characteristics of surface ocean pCO2 and airsea CO2 fluxes, Global Biogeochem. Cy., 26, GB2042, doi:10.1029/2010GB004017, 2012.
27. Kalkhan, M. A.: Spatial Statistics: GeoSpatial Information Modelling and Thematic Mapping, Taylor & Francis Group, 2011.
28. Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Leetmaa, A., Reynolds, R., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Jenne, R., and Joseph, D.: The NCEP/NCAR 40-year reanalysis project, B. Am. Meteorol. Soc., 77, 437-470, 1996.
29. Keller, K., Joos, F., Raible, C. C., Cocco, V., Frölicher, T., Dunne, J. P., Gehlen, M., Bopp, L., Orr, J. C., Tjiputra, J., Heinze, C., Segscheider, J., Roy, T., and Metzl, N.: Variability of the ocean carbon cycle in response to the North Atlantic Oscillation, Tellus, 64, 18738, doi:10.3402/tellusb.v64i0.18738, 2012.
30. Kohonen, T.: Self-Organization and Associative Memory, Springer- Verlag, Berlin, 2nd Edn., 1987.
31. Kohonen, T.: Self-Organizing Maps, Springer-Verlag, Berlin Heidelberg New York, 3rd Edn., 2001.
32. Körtzinger, A.: Methods of Seawater Analysis, chap. Determination of carbon dioxide partial pressure (pCO2), 149-158, Verlag Chemie, 1999.
33. Le Quéré, C., Rödenbeck, C., Buitenhuis, E. T., Conway, T. J., Langenfelds, R., Gomez, A., Labuschagne, C., Ramonet, M., Nakazawa, T., Metzl, N., Gillett, N., and Heimann, M.: Saturation of the Southern Ocean CO2 sink due to recent climate change, Science, 316, 1735-1738, doi:10.1126/science.1136188, 2007. (Pubitemid 46988546)
34. Lefèvre, N., Watson, A. J., Olsen, A., Rios, A. F., Pérez, F. F., and Johannessen, T.: A decrease in the sink for atmospheric CO2 in the North Atlantic, Geophys. Res. Lett., 31, L07306, doi:10.1029/2003GL018957, 2004. (Pubitemid 38870491)
35. Lefèvre, N., Watson, A. J., and Watson, A. R.: A comparison of multiple regression and neural network techniques for mapping in situ pCO2 data, Tellus, 57B, 375-384, 2005. (Pubitemid 41711622)
36. Levitus, S., Antonov, J. I., Boyer, T. P., Baranova, O. K., Garcia, H. E., Locarnini, R. A., Mishonov, A. V., Reagan, J. R., Seidov, D., Yarosh, E. S., and Zweng, M. M.: World ocean heat content and thermosteric sea level change (0-2000 m), 1955-2010, Geophys. Res. Lett., 39, L10603, doi:10.1029/ 2012GL051106, 2012.
37. Lüger, H., Wanninkhof, R., Wallace, D. W. R., and Körtzinger, A.: CO2 fluxes in the subtropical and subarctic North Atlantic based on measurements from a volunteer observing ship, J. Geophys. Res., 111, C06024, doi:10.1029/2005JC003101, 2006. (Pubitemid 44768134)
38. Marquardt, D. W.: An Algorithm for Least-Squares Estimation of Nonlinear Parameters, J. Soc. Ind. Appl. Math., II, 431-441, 1963.
39. Marshall, J., Kushnir, Y., Battisti, D., Chang, P., Czaja, A., Dickson, R., Hurrel, J., McCartney, M., Saravanan, R., and Visbeck, M.: North Atlantic Climate Variability: Phenomena, Impacts and Mechanisms, Int. J. Climatol., 21, 1863-1898, doi:10.1002/joc.693, 2001. (Pubitemid 34161910)
40. McKinley, G. A., Fay, A. R., Takahashi, T., and Metzl, N.: Convergence of atmospheric and North Atlantic carbon dioxide trends on multidecadal timescales, Nat. Geosci., 4, 606-610, doi:10.1038/NGEO1193, 2011.
41. Menemenlis, D., Campin, J., Heimbach, P., Hill, C., Lee, T., Nguyen, A., Schodlok, M., and Zhang, H.: ECCO2: High resolution global ocean and sea ice data synthesis, Mercator Ocean Quarterly Newsletter, 31, 13-21, 2008.
42. Metzl, N., Corbière, A., Reverdin, G., Lenton, A., Takahashi, T., Olsen, A., Johannessen, T., Pierrot, D., Wanninkhof, R., Ólafsdó ttir, S. R., Olafsson, J., and Ramonet, M.: Recent acceleration of the sea surface fCO2 growth rate in the North Atlantic subpolar gyre (1993-2008) revealed by winter observations, Global Biogeochem. Cy., 24, GB4004, doi:10.1029/2009gb003658, 2010.
43. Mikaloff Fletcher, S. E., Gruber, N., Jacobson, A. R., Doney, S. C., Dutkiewicz, S., Gerber, M., Follows, M., Joos, F., Lindsay, K., Menemenlis, D., Mouchet, A., Müller, S. A., and Sarmiento, J. L.: Inverse estimates of anthropogenic CO2 uptake, transport, and storage by the ocean, Global Biogeochem. Cy., 20, GB2002, doi:10.1029/2005GB002530, 2006. (Pubitemid 44755526)
44. Mikaloff Fletcher, S. E., Gruber, N., Jacobson, A. R., Gloor, M., Doney, S. C., Dutkiewicz, S., Gerber, M., Follows, M., Joos, F., Lindsay, K., Menemenlis, D., Mouchet, A., Müller, S. A., and Sarmiento, J.: Inverse estimates of the oceanic sources and sinks of natural CO2 and the implied oceanic carbon transport, Global Biogeochem. Cy., 21, GB1010, doi:10.1029/2006GB002751, 2007. (Pubitemid 46831863)
45. Olsen, A., Omar, A. M., Bellerby, R. G. J., Johannessen, T., Ninnemann, U. S., Brown, K. R., Olsson, K. A., Olafsson, J., Nondal, G., Kivimäe, C., Kringstad, S., Neill, C., and Olafsdottir, S.: Magnitude and origin of the anthropogenic CO2 increase and 13C Suess effect in the Nordic seas since 1981, Global Biogeochem. Cy., 20, GB3027, doi:10.1029/2005GB002669, 2006. (Pubitemid 46761046)
46. Peng, T.-H. and Wanninkhof, R.: Increase in anthropogenic CO2 in the Atlantic Ocean in the last two decades, Deep-Sea Res. Pt. I, 57, 755-770, 2010.
47. Peylin, P., Law, R. M., Gurney, K. R., Chevallier, F., Jacobson, A. R., Maki, T., Niwa, Y., Patra, P. K., Peters, W., Rayner, P. J., Rödenbeck, C., van der Laan-Luijkx, I. T., and Zhang, X.: Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions, Biogeosciences, 10, 6699-6720, doi:10.5194/bg-10-6699-2013, 2013.
48. Pfeil, B., Olsen, A., Bakker, D. C. E., Hankin, S., Koyuk, H., Kozyr, A., Malczyk, J., Manke, A., Metzl, N., Sabine, C. L., Akl, J., Alin, S. R., Bates, N., Bellerby, R. G. J., Borges, A., Boutin, J., Brown, P. J., Cai, W.-J., Chavez, F. P., Chen, A., Cosca, C., Fassbender, A. J., Feely, R. A., González-Dávila, M., Goyet, C., Hales, B., Hardman-Mountford, N., Heinze, C., Hood, M., Hoppema, M., Hunt, C. W., Hydes, D., Ishii, M., Johannessen, T., Jones, S. D., Key, R. M., Körtzinger, A., Landschützer, P., Lauvset, S. K., Lefèvre, N., Lenton, A., Lourantou, A., Merlivat, L., Midorikawa, T., Mintrop, L., Miyazaki, C., Murata, A., Nakadate, A., Nakano, Y., Nakaoka, S., Nojiri, Y., Omar, A. M., Padin, X. A., Park, G.-H., Paterson, K., Perez, F. F., Pierrot, D., Poisson, A., Ríos, A. F., Santana-Casiano, J. M., Salisbury, J., Sarma, V. V. S. S., Schlitzer, R., Schneider, B., Schuster, U., Sieger, R., Skjelvan, I., Steinhoff, T., Suzuki, T., Takahashi, T., Tedesco, K., Telszewski, M., Thomas, H., Tilbrook, B., Tjiputra, J., Vandemark, D., Veness, T., Wanninkhof, R., Watson, A. J., Weiss, R., Wong, C. S., and Yoshikawa-Inoue, H.: A uniform, quality controlled Surface Ocean CO2 Atlas (SOCAT), Earth Syst. Sci. Data, 5, 125-143, doi:10.5194/essd-5-125-2013, 2013.
49. Rayner, N. A., Parker, D. E., Horton, E. B., Folland, C. K., Alexander, L. V., Rowell, D. P., Kent, E. C., and Kaplan, A.: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century, J. Geophys. Res., 108, 4407, doi:10.1029/2002JD002670, 2003.
50. Reynolds, R. W., Rayner, N. A., Smith, T. M., Stokes, D. C., and Wang, W.: An improved in situ and satellite SST analysis for climate, J. Climate, 15, 1609-1625, 2002.
51. Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L., Wanninkhof, R., Wong, C. S., Wallace, D. W. R., Tilbrook, B., Millero, F. J., Peng, T.-H., Kozyr, A., Ono, T., and Rios, A. F.: The oceanic sink for anthropogenic CO2, Science (New York, N.Y.), 305, 367-71, doi:10.1126/science. 1097403, 2004. (Pubitemid 38938147)
52. Sabine, C. L., Hankin, S., Koyuk, H., Bakker, D. C. E., Pfeil, B., Olsen, A., Metzl, N., Kozyr, A., Fassbender, A., Manke, A., Malczyk, J., Akl, J., Alin, S. R., Bellerby, R. G. J., Borges, A., Boutin, J., Brown, P. J., Cai, W.-J., Chavez, F. P., Chen, A., Cosca, C., Feely, R. A., González- Dávila, M., Goyet, C., Hardman-Mountford, N., Heinze, C., Hoppema, M., Hunt, C.W., Hydes, D., Ishii, M., Johannessen, T., Key, R. M., Körtzinger, A., Landschützer, P., Lauvset, S. K., Lefèvre, N., Lenton, A., Lourantou, A., Merlivat, L., Midorikawa, T., Mintrop, L., Miyazaki, C., Murata, A., Nakadate, A., Nakano, Y., Nakaoka, S., Nojiri, Y., Omar, A. M., Padin, X. A., Park, G.-H., Paterson, K., Perez, F. F., Pierrot, D., Poisson, A., Ríos, A. F., Salisbury, J., Santana-Casiano, J. M., Sarma, V. V. S. S., Schlitzer, R., Schneider, B., Schuster, U., Sieger, R., Skjelvan, I., Steinhoff, T., Suzuki, T., Takahashi, T., Tedesco, K., Telszewski, M., Thomas, H., Tilbrook, B., Vandemark, D., Veness, T., Watson, A. J., Weiss, R., Wong, C. S., and Yoshikawa-Inoue, H.: Surface Ocean CO2 Atlas (SOCAT) gridded data products, Earth Syst. Sci. Data, 5, 145-153, doi:10.5194/essd-5-145-2013, 2013.
53. Sarmiento, J. and Gruber, N.: Ocean Biogeochemical Dynamics, Princeton University Press, 2006.
54. Sasse, T. P., McNeil, B. I., and Abramowitz, G.: A new constraint on global air-sea CO2 fluxes using bottle carbon data, Geophys. Res. Lett., 40, 1594-1599, doi:10.1002/grl.50342, 2013.
55. Schuster, U. and Watson, A. J.: A variable and decreasing sink for atrmospheric CO2 in the North Atlantic, J. Geophys. Res., 112, C11006, doi:10.1029/2006JC003941, 2007.
56. Schuster, U., Watson, A. J., Bates, N. R., Corbière, A., González- Dávila, M., Metzl, N., Pierrot, D., and Santana-Casiano, M.: Trends in North Atlantic sea-surface fCO2 from 1990 to 2006, Deep-Sea Res. Pt. II, 56, 620-629, 2009.
57. Schuster, U., McKinley, G. A., Bates, N., Chevallier, F., Doney, S. C., Fay, A. R., González-Dávila, M., Gruber, N., Jones, S., Krijnen, J., Landschützer, P., Lefèvre, N., Manizza, M., Mathis, J., Metzl, N., Olsen, A., Rios, A. F., Rödenbeck, C., Santana- Casiano, J. M., Takahashi, T., Wanninkhof, R., and Watson, A. J.: An assessment of the Atlantic and Arctic sea-air CO2 fluxes, 1990-2009, Biogeosciences, 10, 607-627, doi:10.5194/bg-10- 607-2013, 2013.
58. Stendardo, I. and Gruber, N.: Oxygen trends over five decades in the North Atlantic, J. Geophys. Res., 117, C11004, doi:10.1029/2012JC007909, 2012.
59. Sweeney, C., Gloor, E., Jacobson, A. R., Key, R. M., McKinley, G., Sarmiento, J. L., and Wanninkhof, R.: Constraining global air-sea gas exchange for CO2 with recent bomb 14C measurements, Global Biogeochem. Cy., 21, GB2015, doi:10.1029/2006GB002784, 2007. (Pubitemid 47323964)
60. Takahashi, T., Olafsson, J., Goddard, J., Chipman, D., and Sutherland, S.: Seasonal variation of CO2 and nutrients in the highlatitude surface oceans: A comparative study, Global Biogeochem. Cy., 7, 843-878, doi:10.1029/93GB02263, 1993. (Pubitemid 24430526)
61. Takahashi, T., Wanninkhof, R., Feely, R., Weiss, R., Chipman, D., Bates, N., Olafsson, J., Sabine, C., and Sutherland, S.: Net seaair CO2 flux over the global oceans: An improved estimate based on the sea-air pCO2 difference, in: Proceedings of the Second- Internat ional Symposium, CO2 in the Oceans, edited by: Nojiri, Y., Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan, 9-14, 1999.
62. Takahashi, T., Sutherland, S. C., Sweeney, C., Poisson, A., Metzl, N., Tilbrook, B., Bates, N., Wanninkhof, R., Feely, R. F., Sabine, C., Olafsson, J., and Nojiri, Y.: Global sea-air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects, Deep-Sea Res. Pt. II, 49, 1601-1622, 2002. (Pubitemid 34565015)
63. Takahashi, T., Weiss, R., Wanninkhof, R., Chipman, D., and Feely, R.: Global air-sea flux of CO2: an estimate based on measurements of sea-air pCO2 difference, P. Natl. Acad. Sci., 94, 8292- 8299, 2003.
64. Takahashi, T., Sutherland, S., Wanninkhof, R., Sweeney, C., Feely, R., Chipman, D., Hales, B., Friederich, G., Chavez, F., Sabine, C., Watson, A., Bakker, D., Schuster, U., Metzl, N., Yoshikawa- Inoue, H., Ishii, M., Midorikawa, T., Nojiri, Y., Körtzinger, A., Steinhoff, T., Hoppema, M., Olafson, J., Arnarson, T., Tilbrook, B., Johannessen, T., Olsen, A., Bellerby, R., Wong, C., Delille, B., Bates, N., and de Baar, H.: Climatological mean and decadal change in surface ocean pCO2, and net sea-air CO2 flux over the global oceans, Deep-Sea Res. Pt. II, 56, 554-577, 2009.
65. Telszewski, M., Chazottes, A., Schuster, U., Watson, A. J., Moulin, C., Bakker, D. C. E., González-Dávila, M., Johannessen, T., Körtzinger, A., Lüger, H., Olsen, A., Omar, A., Padin, X. A., Ríos, A. F., Steinhoff, T., Santana-Casiano, M., Wallace, D. W. R., and Wanninkhof, R.: Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network, Biogeosciences, 6, 1405-1421, doi:10.5194/bg-6-1405- 2009, 2009.
66. Thomas, H., Prowe, F. A. E., Lima, I. D., Doney, S. C., Wanninkhof, R., Greatbatch, R. J., Schuster, U., and Corbière, A.: Changes in the North Atlantic Oscillation influence CO2 uptake in the North Atlantic over the past 2 decades, Global Biogeochem. Cy., 22, GB4027, doi:10.1029/2007GB003167, 2008.
67. Ullman, D. J., McKinley, G. A., Bennington, V., and Dutkiewicz, S.: Trends in the North Atlantic carbon sink: 1992-2006, Global Biogeochem. Cy., 23, GB4011, doi:10.1029/2008GB003383, 2009.
68. Vesanto, J., Himberg, J., Alhoniemi, E., and Parhankangas, J.: SOM Toolbox for Matlab 5, Tech. rep., Helsinki University of Technology, 2000.
69. Wanninkhof, R.: Relation between wind speed and gas exchange over the ocean, J. Geophys. Res., 97, 7373-7383, 1992.
70. Wanninkhof, R., Doney, S., Bullister, J. L., Levine, N. M., Warner, M., and Gruber, N.: Detecting anthropogenic CO2 changes in the interior Atlantic Ocean between 1989 and 2005, J. Geophys. Res., 115, C11028, doi:10.1029/ 2010JC006251, 2010.
71. Weiss, R. F.: Carbon Dioxide inWater and Seawater: The Solubility of a Non-Ideal Gas, Mar. Chem., 2, 203-215, 1974.