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Glacial Water Mass Geometry and the Distribution of d 13 C of S CO 2 in the Western Atlantic

Glacial Water Mass Geometry and the Distribution of d 13 C of S CO 2 in the Western Atlantic. William Curry Delia Oppo Department of Geology and Geophysics Woods Hole Oceanographic Institution. Fate of Fossil Fuel CO 2 in the Ocean. Shackleton (1977). M12392 Atlantic d 13 C

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Glacial Water Mass Geometry and the Distribution of d 13 C of S CO 2 in the Western Atlantic

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  1. Glacial Water Mass Geometry and the Distribution of d13C of SCO2 in the Western Atlantic William Curry Delia Oppo Department of Geology and Geophysics Woods Hole Oceanographic Institution

  2. Fate of Fossil Fuel CO2 in the Ocean Shackleton (1977)

  3. M12392 Atlantic d13C Glacial = -1.2 ‰ PDB Shackleton (1977)

  4. Y71-6-12MG Pacific d13C Same as Atlantic During Glacial Shackleton (1977)

  5. Conservative Mixing NADW High Salinity – High d13C AABW Low Salinity – Low d13C

  6. NADW GEOSECS

  7. NADW Kroopnick (1985)

  8. Benthic Foraminifera Cibicidoides sp. Cibicides sp. Planulina sp. d13C of SCO2 ~d13C of CaCO3 Data sources: Duplessy et al., 1984 Curry and Lohmann, 1990 Mackensen et al., 1993 McCorkle and Keigwin, 1994

  9. AAIW UCPDW South Atlantic Water Masses NADW LCPDW

  10. Sedimentation Rates: ~ 10 cm kyr-1 above 1500 m ~ 5 cm kyr-1 below 2000 m

  11. Cibidicoides at Brazil Margin GNAIW NADW Curry and Oppo (in press)

  12. North versus South Atlantic GNAIW Curry and Oppo (in press)

  13. Core locations New Brazil Margin Cores (Curry and Oppo) New Blake Ridge Cores (Keigwin) Curry and Oppo (in press)

  14. Curry and Oppo (in press)

  15. Curry and Oppo (in press)

  16. Curry and Oppo (in press)

  17. Curry and Oppo (in press)

  18. North versus South Atlantic GNAIW Curry and Oppo (in press)

  19. Vertical Mixing Along the MAR Mauritzen et al. (2002)

  20. North versus South Atlantic GNAIW Curry and Oppo (in press)

  21. Summary • Carbon isotope tracers show the presence of three water masses a reduced volume and shoaling of NADW – GNAIW. • GNAIW southward penetration to 26º S. Intermediate water mass northward penetration unconstrained by carbon isotopes. • Bathymetric and meridional gradients in d13C much larger because of changes in end member water mass properties. • Bathymetric gradients in d13C imply that lateral advection remained strong with respect to expected strong vertical mixing.

  22. What’s in the d18O Data?

  23. North versus South Atlantic GNAIW Curry and Oppo (in press)

  24. 30 ºS to 30 ºN DT = 4 ºC

  25. d18O gradient at Constant Density 0.6 permil

  26. Global SSS and E-P distributions Source: R.Schmitt,WHOI Source: HydroBase2 Sea surface salinity distributions are determined in large part by E-P patterns

  27. Large Scale Ocean Circulation

  28. Vema Channel Curry and Lohmann (1982)

  29. Glacial Southern Ocean d13C slightly higher than Atlantic and Pacific (-0.9‰ > -1.2‰ PDB) Shackleton (1977)

  30. Curry and Lohmann (1982)

  31. Bathymetric Changes in Dd13C – Decreased NADW Curry and Lohmann (1982)

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