Bibliography - C. L. Sabine

1. Hamme, Roberta C., N. Cassar, Veronica P. Lance, Robert D. Vaillancourt, Michael Bender, Peter G. Strutton, Tommy S. Moore, Michael D. DeGrandpre, C. L. Sabine, D. T. Ho, and Bruce R. Hargreaves, 2012: Dissolved O₂/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean. Journal of Geophysical Research, American Geophysical Union, 117(C00F12), doi:10.1029/2011JC007046
   [ Abstract ]

   We use continuous and discrete measurements of the dissolved O₂/Ar ratio in the mixed layer to investigate the dynamics of biological productivity during the Southern Ocean Gas Exchange Experiment in March and April 2008. Injections of SF₆ defined two water masses (patches) that were followed for up to 2 weeks. In the first patch, dissolved O₂/Ar was supersaturated, indicating net biological production of organic carbon. In the second patch, rapidly decreasing O₂/Ar could only be reasonably explained if the mixed layer was experiencing a period of net heterotrophy. The observations rule out dominant contributions from vertical mixing, lateral dilution, or respiration in the ship's underway seawater supply lines. We also compare nine different estimates of net community, new, primary, or gross production made during the experiment. Net community and new production estimates agreed well in the first patch but disagreed in the second patch, both during an initial net heterotrophic period but also during the apparently autotrophic period at the end of the observations. Rapidly changing productivity during the second patch complicated the comparison of methods that integrate over daily and several week timescales. Primary productivity values from on-deck 24 h ¹⁴C incubations and gross carbon production values from photosynthesis-irradiance experiments were nearly identical even during highly dynamic periods of net heterotrophy, while gross oxygen production measurements were 3.5—4.2 times higher but with uncertainties in that ratio near ±2. These comparisons show that the photosynthesis-irradiance experiments based on 1—2 h ¹⁴C incubations underestimated gross carbon production.

2. Gloor, M. N., N. Gruber, Jorge Sarmiento, C. L. Sabine, R. A. Feely, and C. Rödenbeck, 2008: A first estimate of present and pre-industrial CO₂ flux patterns based on ocean interior carbon measurements and models. Geophysical Research Letters, 30(1), doi:10.1029/2002GL015594
   [ Abstract ]

   The exchange of CO₂ across the air-sea interface is a main determinant of the distribution of atmospheric CO₂ from which major conclusions about the carbon cycle are drawn, yet our knowledge of atmosphere-ocean fluxes still has major gaps. A new analysis based on recent ocean dissolved inorganic carbon data and on models permits us to separately estimate the preindustrial and present air-sea CO₂ flux distributions without requiring knowledge of the gas exchange coefficient. We find a smaller carbon sink at mid to high latitudes of the southern hemisphere than previous data based estimates and a shift of ocean uptake to lower latitude regions compared to estimates and simulations. The total uptake of anthropogenic CO₂ for 1990 is 1.8 (±0.4) Pg C yr^-1. Our ocean based results support the interpretation of the latitudinal distribution of atmospheric CO₂ data as evidence for a large northern hemisphere land carbon sink.

3. Iglesias-Rodriguez, M., R. A. Armstrong, R. A. Feely, R. Hood, J. Kleypas, J. D. Milliman, C. L. Sabine, and Jorge Sarmiento, 2002: The Marine Calcium Carbonate Budget in a Changing Ocean. EOS Transactions, 83(34), 374-375
   [ Abstract ]

   Many of the uncertainties in diagnostic and prognostic marine carbon cycle models arise from an imperfect understanding of processes that control formation and dissolution of calcium carbonate (CaCO₃). On the production side of the equation, factors that control the abundances of calcifying phytoplankton (coccolithophorids) or zooplankton (foraminifera and pteropods) are largely unknown. On the dissolution side, changes in the depth of CaCO₃ saturation horizons (for both calcite and aragonite) may produce large-scale changes in dissolution of shelf and slope sediments and reefs, with potentially significant implications for atmospheric carbon dioxide concentration and climate change, and for coralline organisms themselves. In this article we summarize our present understanding of the marine CaCO₃ cycle, including information presented at the 2001 US JGOFS Workshop on Marine Calcification (http://usjgofs.whoi.edu/mzweb/caco3_rpt.html), and highlight gaps in our understanding of key mechanisms that may affect future changes in the CaCO₃ budget.

4. Orr, J. C., E. Maier-Reimer, U. Mikolajewicz, P. Monfray, Jorge Sarmiento, J. R. Toggweiler, N. K. Taylor, J. Palmer, N. Gruber, C. L. Sabine, C. Le Quere, R. M. Key, and J. Boutin, 2001: Estimates of anthropogenic carbon uptake from four three-dimensional global ocean models. Global Biogeochemical Cycles, http://www.agu.org/pubs/crossref/2001/2000GB001273.shtml, 15(1), 43-60
   [ Abstract ]

   We have compared simulations of anthropogenic CO₂ in the four three dimensional ocean models that participated in the first phase of the Ocean Carbon-Cycle Model Intercomparison Project (OCMIP), as a means to identify their major differences. Simulated global uptake agrees to within ±19%, giving a range of 1.85 ± 0.35 Pg Cy r^-1 for the 1980-1989 average. Regionally, t he Southern Ocean dominates the present-day air-sea flux of anthropogenic CO₂ in all models, with one third to one half of the global uptake occurring south of 30°S. The highest simulated total uptake in the Southern Ocean was 70% larger than the lowest. Comparison with recent data-based estimates of anthropogenic CO₂ suggest that most of the models substantially overestimate storage in the Southern Ocean; elsewhere they generally underestimate storage by less than 20%. Globally, the OCMIP models appear to bracket the real ocean's present uptake, based on comparison of regional data-based estimates of anthropogenic CO₂ and bomb ¹⁴C. Column inventories of bomb ¹⁴C have become more similar to those for anthropogenic CO₂ with the time that has elapsed between the Geochemical Ocean Sections Study (1970s) and Word Ocean Circulation Experiment ( 1990s) global sampling campaigns. Our ability to evaluate simulated anthropogenic CO₂ would improve if systematic errors associated with the data-based estimates could be provided regionally.

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