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Oceanic sources and sinks for atmospheric CO 2

Oceanic sources and sinks for atmospheric CO 2. Nicolas Gruber (1) , S.E Mikaloff-Fletcher (1) , Jacobson (2) , M. Gloor (2) , J. L. Sarmiento (2) , T. Takahashi (3) , and OIP members Department of Atmospheric and Oceanic Sciences & IGPP, UCLA AOS Program, Princeton University

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Oceanic sources and sinks for atmospheric CO 2

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  1. Oceanic sources and sinks for atmospheric CO2 Nicolas Gruber(1), S.E Mikaloff-Fletcher(1), Jacobson(2), M. Gloor(2), J. L. Sarmiento(2), T. Takahashi(3), and OIP members Department of Atmospheric and Oceanic Sciences & IGPP, UCLA AOS Program, Princeton University Lamont-Doherty Earth Observatory of Columbia (4) Ocean Inversion Project

  2. 1980-1999

  3. Globally integrated flux: 2.2 PgC yr-1

  4. TWO VIEWS OF CO2 FLUXES IN THE SOUTHERN OCEAN Takahashi et al. (2002) u2 a la Wanninkhof et al. (2001) TRANSCOM Gurney et al. (2002) 0.86 Pg C yr-1 0.47±0.40 Pg C yr-1

  5. INVERSION OF OCEAN INTERIOR OBSERVATIONS • Basis functions are model simulated footprints of unit emissions from a number of fixed regions • Estimate linear combination of basis functions that fits observations in a least squares sense. • Inversion is analogous to linear regression footprints fluxes obs Premultiply both sides by inverse of A estimated fluxes

  6. OCEAN INVERSION METHOD • The ocean is divided into n regions (n = 23)

  7. ESTIMATING DCgasex AND Cant Since the observed DIC includes the impact of biology, we need to remove this component to obtain a tracer that just reflects the exchange of CO2 across the air-sea interface of natural and anthropogenic CO2: DCgasex+ Cant= DICobs - DCbio + const DCbio : biological component, estimated from nutrients and Alkalinity Cant : anthropogenic component, estimated using the DC* method of Gruber et al. [1996] DCgasex : gasexchange component, estimated by difference

  8. Global uptake (1995): 2.20±0.25 Pg C y-1

  9. DATA: Cant and DCgasex DCgasex = DICobs - DCbio - Cant - const Cant : estimated by DC* method Gruber et al., (1996) Gruber and Sarmiento (2002)

  10. SOUTHERN OCEAN FLUXES

  11. SUMMARY • The reconstructed oceanic distribution of anthropogenic CO2 suggests an uptake rate of 2.20±0.25 Pg C yr-1. • The Southern Ocean is currently a weak sink, a result of the strong uptake flux anthropogenic CO2 in this region outweighting the outgassing of natural CO2. • This small Southern Ocean sink of about 0.40±0.35 Pg C yr-1 is consistent with most recent analyses, but is much smaller than the flux estimates based on the Takahashi et al. (2002) climatology.

  12. THE END.

  13. Ocean Inversion: PARTICIPATING MODELS

  14. Global Anthropogenic Uptake(Pg C/yr, scaled to 1995)

  15. Anthropogenic Carbon Flux 59S-44S 44S-18S 18S-18N ~18N-49N

  16. Pre-Industrial Carbon Flux 59S-44S 44S-18S 18S-18N ~18N-49N

  17. Contemporary Carbon Flux 18S-18N ~18N-49N 59S-44S 44S-18S

  18. Latitude Bern-3D PRINCE-HH ECCO PRINCE-LHS MIT PRINCE-2 NCAR PRINCE-2a PRINCE-LL UL Inverse Flux Estimates OCMIP Forward Flux Estimates

  19. Preindustrial Carbon Transport Northward Transport (Gg C/m/yr Latitude

  20. Bern-3D PRINCE-HH ECCO PRINCE-LHS MIT PRINCE-2 NCAR PRINCE-2a PRINCE-LL UL Integrated (1765-1995) Anthropogenic Carbon Uptake Inverse Estimates Forward Estimates Latitude

  21. THE CHANGE OF SOUTHERN OCEAN CO2 FLUXES OVER TIME (mol m-2 yr-1) Pre-industrial CO2 fluxes 1995 CO2 fluxes KVLOW-AILOW model

  22. Southern Ocean Data Inverse Flux Estimates Preliminary ∆pCO2 Data From T. Takahashi

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