Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 5 3 2008 10.5194/bg-5-875-2008 http://www.biogeosciences.net/5/875/2008/ http://www.biogeosciences.net/5/875/2008/bg-5-875-2008.html http://www.biogeosciences.net/5/875/2008/bg-5-875-2008.pdf 875 889 2008-06-02 Impact of variable air-sea O₂ and CO₂ fluxes on atmospheric potential oxygen (APO) and land-ocean carbon sink partitioning C. D. Nevison N. M. Mahowald S. C. Doney I. D. Lima N. Cassar National Center for Atmospheric Research, Boulder, Colorado, USA Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA Dept. of Geoscience, Princeton University, Princeton, NJ, USA now at: Cornell University, Ithaca, NY, USA A three dimensional, time-evolving field of atmospheric potential oxygen (APO ~O₂/N₂+CO₂) was estimated using surface O₂, N₂ and CO₂ fluxes from the WHOI ocean ecosystem model to force the MATCH atmospheric transport model. Land and fossil carbon fluxes were also run in MATCH and translated into O₂ tracers using assumed O₂:CO₂ stoichiometries. The modeled seasonal cycles in APO agree well with the observed cycles at 13 global monitoring stations, with agreement helped by including oceanic CO₂ in the APO calculation. The modeled latitudinal gradient in APO is strongly influenced by seasonal rectifier effects in atmospheric transport. An analysis of the APO-vs.-CO₂ mass-balance method for partitioning land and ocean carbon sinks was performed in the controlled context of the MATCH simulation, in which the true surface carbon and oxygen fluxes were known exactly. This analysis suggests uncertainty of up to ±0.2 PgC in the inferred sinks due to variability associated with sparse atmospheric sampling. It also shows that interannual variability in oceanic O₂ fluxes can cause large errors in the sink partitioning when the method is applied over short timescales. However, when decadal or longer averages are used, the variability in the oceanic O₂ flux is relatively small, allowing carbon sinks to be partitioned to within a standard deviation of 0.1 Pg C/yr of the true values, provided one has an accurate estimate of long-term mean O₂ outgassing. Andres, R. J., Marland, G., Fung, I., and Matthews, E.: A 1$^\circ\times$ 1° distribution of carbon dioxide emissions from fossil fuel consumption and cement manufacture, 1950–1990, Glob. Biogeochem. Cy., 10, 419–429, 1996. Balkanski, Y., Monfray, P., Battle, M., and Heimann, M.: Ocean primary production derived from satellite data: An evaluation with atmospheric oxygen measurements. Glob. Biogeochem. Cy., 13, 257–271, 1999. Battle, M., Bender, M. L., Tans, P. P., White, J. W. C, Ellis, .J. T., Conway, T., and Francey, R. J.: Global carbon sinks and their variability inferred from atmospheric and $\delta ^13$C, Science, 287, 2467–2470, 2000. Battle, M., Mikaloff Fletcher, S., Bender, M. L., Keeling, R. F., et al.: Atmospheric potential oxygen: New observations and their implications for some atmospheric and oceanic models, Glob. Biogeochem. Cy., 20, GB1010, doi:10.1029/2005GB002534, 2006. Bender, M., Ellis, T., Tans, P., Francey, R., and Lowe, D.: Variability in the O₂/N₂ ratio of southern hemisphere air, 1991–1994: Implications for the carbon cycle, Glob. Biogeochem. Cy., 10, 9–21, 1996. Bender, M., Ho, D., Hendricks, M. B., Mika, R., Battle, M. O., Tans, P., Conway, T. J., Sturtevant, P. B., and Cassar, N.: Atmospheric O₂/N₂ changes, 1993–2002: Implications for the partitioning of fossil fuel CO₂ sequestration, Glob. Biogeochem. Cy., 19, GB4017, doi:10.1029/2004GB002410, 2005. Blaine, T. W.: Continuous Measurements of Atmospheric Ar/N₂ as a Tracer of Air-Sea Heat Flux: Models, Methods, and Data, Ph. D. Thesis, University of California, San Diego, La Jolla, 225 pp., 2005. Bopp, L., Le Quere, C., Heimann, M., Manning, A. C., and Monfray, P.: Climate-induced oceanic oxygen fluxes: Implications for the contemporary carbon budget, Glob. Biogeochem. Cy., 16, GB1022, doi:10.1029/2001GB001445, 2002. Brenkert, A. L.: Carbon dioxide emission estimates from fossil-fuel burning, hydraulic cement production, and gas flaring for 1995 on a one degree grid cell basis, (available at http://cdiac.esd.ornl.gov/ndps/ndp058a.html), 1998. Denning, A. S., Fung, I. Y., and Randall, D. A.: Latitudinal gradient of atmospheric CO₂ due to seasonal exchange with land biota, Nature, 376, 240–243, 1995. Doney, S. C., Glover, D. M., and Najjar, R. G.: A new coupled, one-dimensional biological-physical model for the upper ocean: Applications to the JGOFS Bermuda Atlantic Time-series Study (BATS) site, Deep-Sea Res. Pt. II, 43, 591–624, 1996. Doney, S. C., Large, W. G., and Bryan, F. O.: Surface ocean fluxes and water-mass transformation rates in the coupled NCAR Climate System Model, J. Climate, 11, 1420–1441, 1998. Doney, S. C., Yeager, S., Danabasoglu, G., Large, W. G., and McWilliams, J. C.: Mechanisms governing interannual variability of upper ocean temperature in a global hindcast simulation, J. Phys. Oceanogr., 37, 1918–1938, 2007. Garcia, H. E. and Keeling, R. F.: On the global oxygen anomaly and air-sea flux, J. Geophys. Res., 106, 31 155–31 166, 2001. Gloor, M., Gruber, N., Hughes, T. M., and Sarmiento, J. L.: An inverse modeling method for estimation of net air-sea fluxes from bulk data: Methodology and application to the heat cycle, Glob. Biogeochem. Cy., 15, 767–782, 2001. Gruber, N., Gloor, M., Fan, S.-M., and Sarmiento, J. L.: Air-sea flux of oxygen estimated from bulk data: Implications for the marine and atmospheric oxygen cycles, Glob. Biogeochem. Cy., 15, 783–803, 2001. Gurney, K. R., Law, R. M., Denning, A. S., Rayner, P. J., et al.: Transcom 3 CO₂ inversion intercomparison: 1. Annual mean control results and sensitivity to transport and prior flux information, Tellus B, 55, 555–579, 2003. Hamme, R.C., Keeling, R.F., and Paplawsky, W.J.: Explaining observed variability in the interhemispheric gradient of atmospheric potential oxygen, AGU Fall Meeting, San Francisco, USA, 11–15 December 2006, OS52C-03, 2006. Jin, X., Najjar, R. G., Louanchi, F., and Doney, S. C.: A modeling study of the seasonal oxygen budget of the global ocean. J. Geophys. Res., 112, C05017, doi:10.1029/2006JC003731, 2007. Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., et al.: The NMC/NCAR 40-year reanalysis project, B. Am. Meteorol. Soc., 77, 437–471, 1996. Keeling, R. F. and Shertz, S. R.: Seasonal and interannual variations in atmospheric oxygen and implications for the global carbon cycle, Nature, 358, 723–727, 1992. Keeling, R. F. and Garcia, H. E.: The change in oceanic O₂ inventory associated with recent global warming, P. Natl. Acad. Sci. USA, 99, 7848–7853, 2002. Keeling, C. D., Piper, S. C., and Heimann, M.: in Aspects of climate variability in the Pacific and Western Americas, AGU Monograph, 55, edited by: Peterson, D. H. (AGU, Washington DC), 305–363, 1989. Keeling, R. F., Najjar, R. P., Bender, M. L., and Tans, P. P.: What atmospheric oxygen measurements can tell us about the global carbon cycle, Glob. Biogeochem. Cy., 7, 37–67, 1993. Keeling, R. F., Piper, S. C., and Heimann, M.: Global and hemispheric CO₂ sinks deduced from changes in atmospheric O₂ concentration, Nature, 391, 218–221, 1996. Keeling, R. F., Stephens, B. B., Najjar, R. G., Doney, S. C., Archer, D., and Heimann, M.: Seasonal variations in the atmospheric O₂/N₂ ration in relation to the kinetics of air-sea gas exchange, Glob. Biogeochem. Cy., 12, 141–163, 1998. Le Quéré, C., Aumont, O., Bopp, L., Bousquet, P., et al.: Two decades of ocean CO₂ sink and variability, Tellus B, 55, 649–656, 2003. Mahowald, N. M., Rasch, P. J., Eaton, B. E., Whittlestone, S., and Prinn, R. G.: Transport of radon-222 to the remote troposphere using the Model of Atmospheric Transport and Chemistry and assimilated winds from ECMWF and the National Center for Environmental Prediction/NCAR, J. Geophys. Res., 102, 28,139–28,151, 1997. Manning, A. C. and Keeling, R. F.: Global oceanic and land biotic carbon sinks from the Scripps atmospheric oxygen flask sampling network, Tellus B, 58, 95–116, 2006. Marland, G., Boden, T. A., and Andres, R. J.: Global, regional, and national CO₂ emissions, in Trends: A Compendium of Data on Global Change, pp. 505–584, Carbon Dioxide Inf. Anal. Cent., Oak Ridge Natl. Lab., US Dep. of Energy, Oak Ridge, Tenn., (available at http://cdiac.esd.ornl.gov/trends/emis/tre_glob.htm), 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. McKinley, G. A., Follows, M. J., Marshall, J., and Fan, S.M.: Interannual variability of air-sea O₂ fluxes and the determination of CO₂ sinks using atmospheric O₂/N₂, Geophys. Res. Lett., 30, 1101, doi:10.1029/2002GL016044, 2003. Moore, J. K., Doney, S. C., Kleypas, J. C., Glover, D. M., and Fung, I.Y.: An intermediate complexity marine ecosystem model for the global domain, Deep-Sea Res. Pt. II, 49, 403–462, 2002. Moore, J. K., Doney, S. C., and Lindsay, K.: Upper ocean ecosystem dynamics and iron cycling in a global three-dimensional model, Glob. Biogeochem. Cy., 18, GB4028, doi:10.1029/2004GB002220, 2004. Naegler, T., Ciais, P., Orr, J. C., Aumont, O., and Roedenbeck, C.: On evaluating ocean models with atmospheric potential oxygen, Tellus, 59B, 138–156, 2007. Najjar, R. G. and Keeling, R. F: Mean annual cycle of the air-sea oxygen flux: A global view, Glob. Biogeochem. Cy. 14(2), 573–584, 2000. Nevison, C. D., Keeling, R. F., Weiss, R. F., Popp, B. N., Jin, X., Fraser, P. J., Porter, L. W., and Hess, P. G.: Southern Ocean ventilation inferred from seasonal cycles of atmospheric N₂O and O₂/N₂ at Cape Grim, Tasmania, Tellus, 57B, 218–229, 2005. Nevison, C. D., Mahowald, N. M., Doney, S. C., Lima, I. D., van der Werf, G. R., Randerson, J. T., Baker, D. F., Kasibhatla, P., and McKinley, G. A.: Contribution of ocean, fossil fuel, land biosphere and biomass burning carbon fluxes to seasonal and interannual variability in atmospheric CO₂, J. Geophys. Res., 113, G01010, doi:10.1029/2007JG000408, 2008. Olsen, S. C. and Randerson, J. T.: Differences between surface and column atmospheric CO₂ and implications for carbon cycle research, J. Geophys. Res., 109, D02301, doi:10.1029/2003JD003968, 2004. Pearman, G. I. and Hyson, P.: Activities of the Global Biosphere as Reflected in Atmospheric CO₂ Records, J. Geophys. Res., 85, 4457–4467, 1980. Plattner, G. K., Joos, F., and Stocker, T. F.: Revision of the global carbon budget due to changing air-sea oxygen fluxes, Glob. Biogeochem. Cy., 16, GB1096, doi:10.1029/2001GB001746, 2002. Prentice, I. C., Farquhar, G. D., Fasham, M. J. R., Goulden, M. L., Heimann, M., Jaramillo, V. J., Kheshgi, H. S., and Le Quéré, C.: The carbon cycle and atmospheric carbon \vadjustdioxide, in Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Houghton J. T., Ding, Y., Griggs, D. J., et al., pp. 183–287, Cambridge Univ. Press, New York, 2001. Randerson, J. T., van der Werf, G. R., Collatz, G. J., Giglio, L., Still, C. J., Kasibhatla, P., Miller, J. B., White, J. W. C., DeFries, R. S., and Kasischke, E. S.: Fire emissions from C3 and C4 vegetation and their influence on interannual variability of atmospheric CO₂ and $\delta ^13$CO₂, Glob. Biogeochem. Cy., 19, GB2019, doi:10.1029/2004GB002366, 2005. Rasch, P. J., Mahowald, N. M., and Eaton, B. E.: Representations of transport, convection, and the hydrologic cycle in chemical transport models: Implications for the modeling of short-lived and soluble species, J. Geophys. Res., 102, 28 127–28 138, 1997. Sarmiento, J. L., Hughes, T. M. C., Stouffer, R. J., and Manabe, S.: Simulated response of the ocean carbon cycle to anthropogenic climate warming, Nature, 393, 245–249, 1998. Severinghaus, J. P.: Studies of the terrestrial O₂ and carbon cycles in sand dune gases and in Biosphere 2, Ph.D. thesis, Columbia University, New York, 1995. Stephens, B. B., Keeling, R. F., Heimann, M., Six, K. D., Murnane, R. and Caldeira, K.: Testing global ocean carbon cycle models using measurements of atmospheric O₂ and CO₂ concentration, Glob. Biogeochem. Cy., 12, 213–230, 1998. Takahashi, T., Poisson, A. Metzl, N., Tilbrook, B., Bates, N., and coauthors: Global sea-air CO₂ flux based on climatological surface ocean $p$CO₂, and seasonal biological and temperature effects, Deep-Sea Res. Pt. II, 49, 1601–1622, 2002. Taylor, K. E.: Summarizing multiple aspects of model performance in a single diagram, J. Geophys. Res., 106, 7183–7192, 2001. Thoning, K. W., Tans, P. P., and Komhyr, W. D.: Atmospheric carbon dioxide at Mauna Loa Observatory: 2. Analysis of the NOAA GMCC data, 1974–1985, J. Geophys. Res., 94, 8549–8565, 1989. Van der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., and Arellano, Jr., A. F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3423–3441, 2006.