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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.

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Presentation on theme: "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."— Presentation transcript:

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

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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 ±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

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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

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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 Takahashi et al. (2002) u 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 PRINCE-LL PRINCE-HH PRINCE-LHS PRINCE PRINCE-2a UL 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 PRINCE-LL PRINCE-HH PRINCE-LHS PRINCE PRINCE-2a UL Mean 2.2 ± ±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 ( ) 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

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


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