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

2. 1980-1999

3. Globally integrated flux: 2.2 PgC yr -1

4. Takahashi et al. (2002) u 2 a la Wanninkhof et al. (2001) TWO VIEWS OF CO 2 FLUXES IN THE SOUTHERN OCEAN TRANSCOM Gurney et al. (2002) 0.86 Pg C yr -1 0.47±0.40 Pg C yr -1

5. 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 footprintsfluxes obs Premultiply both sides by inverse of A INVERSION OF OCEAN INTERIOR OBSERVATIONS estimated fluxes

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

7. ESTIMATING  C gasex AND C ant 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 CO 2 across the air-sea interface of natural and anthropogenic CO 2 :  C gasex + C ant = DIC obs -  C bio + const  C bio : biological component, estimated from nutrients and Alkalinity C ant : anthropogenic component, estimated using the  C* method of Gruber et al. [1996]  C gasex : gasexchange component, estimated by difference

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

12. DATA: C ant and  C gasex  C gasex = DIC obs -  C bio - C ant - const Gruber et al., (1996) Gruber and Sarmiento (2002) C ant : estimated by  C* method

15. StudyAir-sea flux South of ~44°S (Pg C yr -1 ) Mean Inversion (10 models)-0.40±0.35 Takahashi et al. (2002) u 2 -0.86 Takahashi et al. (2002) u 3 -0.94 TRANSCOM-0.47±0.40 McNeil et al. (2005)-0.19±0.26 SOUTHERN OCEAN FLUXES

16. SUMMARY The Southern Ocean is currently a weak sink, a result of the strong uptake flux anthropogenic CO 2 in this region outweighting the outgassing of natural CO 2. 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. The reconstructed oceanic distribution of anthropogenic CO 2 suggests an uptake rate of 2.20±0.25 Pg C yr -1.

17. THE END.

18. Model Radiocarbon Skill Score (weight for preind. CO 2 ) CFC-11 Skill Score (weight for ant. CO 2 ) ECCO NA0.91 MIT NA0.85 NCAR 0.940.91 PRINCE-LL 0.650.80 PRINCE-HH 0.970.87 PRINCE-LHS 0.760.86 PRINCE-2 0.920.87 PRINCE-2a 0.910.85 UL 0.860.76 Bern-3D NA Ocean Inversion: PARTICIPATING MODELS

19. Global Anthropogenic Uptake (Pg C/yr, scaled to 1995) Model Inverse EstimatesOCMIP Forward Estimates Bern-3D 2.05NA ECCO 2.01NA MIT 2.22NA NCAR 2.172.36 PRINCE-LL 1.851.90 PRINCE-HH 2.332.44 PRINCE-LHS 1.992.04 PRINCE-2 2.162.24 PRINCE-2a 2.252.36 UL 2.812.95 Mean 2.2 ± 0.252.3±0.33

20. Anthropogenic Carbon Flux ~18N-49N59S-44S44S-18S18S-18N

21. Pre-Industrial Carbon Flux ~18N-49N59S-44S44S-18S18S-18N

22. Contemporary Carbon Flux ~18N-49N 59S-44S44S-18S 18S-18N

23. Inverse Flux Estimates OCMIP Forward Flux Estimates Latitude Bern-3DPRINCE-HH ECCOPRINCE-LHS MITPRINCE-2 NCARPRINCE-2a PRINCE-LLUL

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

25. Integrated (1765-1995) Anthropogenic Carbon Uptake Inverse Estimates Forward Estimates Latitude Bern-3DPRINCE-HH ECCOPRINCE-LHS MITPRINCE-2 NCARPRINCE-2a PRINCE-LLUL

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

28. Southern Ocean Data Inverse Flux Estimates Preliminary ∆pCO 2 Data From T. Takahashi