WP9: “C ANT quantification and decadal changes in carbon inventory. OBJECTIVES

1. WP9: “CANT quantification and decadal changes in carbon inventory. OBJECTIVES • To establish optimal methods to assess anthropogenic CO2 inventories and its temporal change. • To apply these methods in combination with existing and new highest accuracy data in order to quantify the inventory of anthropogenic CO2 in the Atlantic and Southern Oceans. OUTLINE • CANT Methods • Atlantic CANT inventory • Regional CANT storages • Temporal variation of CANT

2. METHODS Jutteerström et al., to be submitted CFC-nutrient TrOCA TTD ΔC* 2.2 2.3 2.8 3.5 Pg C ΔC* gives an inventory 40% higher

3. METHODS South of 45ºS TrOCA,TTD,φCtº,CºIPSL 5.5, 6.1 6.3 8.0 Pg C ΔC* = 1.3 Pg C Vazquez-Rodriguez et al., 2009 ΔC* inventory 5 times lower

4. METHODS A detailed quantification of air-sea fluxes of natural and anthropogenic carbon and their uncertainties by an Ensemble Kalman Filter Assimilation into the Bern3D model Gerber and Joos, 2009 Contemporary and preindustrial fluxes remain uncertain in the Southern Ocean

5. ATLANTIC CANT INVENTORY Vázquez et al., 2009 CANT inventory average 54 ±8 Pg C (for 1994) in the Atlantic Ocean from 65ºN to Antarctic

6. ATLANTIC CANT INVENTORY USING CARINA WOA05 CARINA Developing of a multiparametric interpolation method CANT inventory 55 ±6 Pg C (for 1994) in the Atlantic Ocean from 65ºN to Antarctic Velo et al., in revision

7. ATLANTIC CANT INVENTORY USING CARINA CANT inventory 51 ±15 Pg C (for 1997) 57 ±16 Pg C (for 2003) in the Atlantic Ocean south of 65ºN VR 5.4% correction from 1994-1997 (50.6 Pg C) Steinfeldt et al., in preparation The temporal increase of CANT inventory between 1997 and 2003 (12%) follows that given by the atmosphere

8. REGIONAL CANT STORAGES Tanhua et al., 2009 Using transient tracer measurements (CFC and SF6) the CANT ranging from 2.5 to 3.3 Pg C, normalized to 2005, was estimated in the Arctic Ocean

9. REGIONAL CANT STORAGES Using four different methods have estimated CANT storage in the Arctic Ocean obtaining a range from 2.2 to 3.5 Pg C. Jutterström et al. (to be submitted) Further south, CANT was estimated using the TTD approach in the Nordic Seas and its sub-regions, Greenland Sea, Norwegian Sea, Iceland Sea, and Denmark Strait (between 0.90 and 1.36 Pg C) Olsen et al. (submitted)

10. REGIONAL CANT STORAGES The CANT storage in North Atlantic water masses was calculated using 16 cruises in the North Atlantic, covering the Iberian, Iceland and Irminger basins, with a high spatial resolution and spanning almost three decades. Pérez et al., see poster

11. REGIONAL CANT STORAGES Pérez et al. (accepted) CANT storage in the Azores region between 1981 and 2004 was evaluated. According to the φCTº and TrOCA approaches the average CANT storage rateswere 1.32±0.11 and 1.18±0.16 mol C·m-2·y-1, respectively

12. REGIONAL CANT STORAGES CANT inventory in the Atlantic for 1997 and 2003 and its relationship to the formation of North Atlantic Deep Water (NADW) was analysed. For the whole region between 20°S and 65°N the inventory amounts to 32.5 ± 9.5 Pg C in 1997 and increases up to 36.0 ± 10.5 Pg C in 2003. Steinfeldt et al., 2009

13. REGIONAL CANT STORAGES Rios et al., to be submitted CANT along section A17 was recomputed using the TROCA and Cº method and compared results with published estimates obtained with the TTD and ΔC* method

14. TEMPORAL VARIATION OF CANT Steinfeldt et al., in preparation Change in the whole water column between 2005 and 1997 is only 3% much less than the 14% expected from atmospheric CO2 increase Temporal variation in the water mass formation in the North Atlantic has a very strong impact in the CANT storage rates.

15. TEMPORAL VARIATION OF CANT Pérez et al., see poster Temporal evolution of the CANT storage rate was estimated along more than two decades (1981–2006) in the Subpolar North Atlantic Ocean, covering the Iberian, Iceland and Irminger basins A tendency of decreasing CANT storage rates towards the deep layers

16. TEMPORAL VARIATION OF CANT The storage rates (±std. err. of the estimate) Pérez et al., see poster Strong reduction, of about three times, in the CANT inventory between high and low NAO scenarios in the Irminger Sea related with the water mass formation.

17. CONCLUSIONS / HIGHLIGHTS • Very good agreement between most recent methods are found along the whole Atlantic, except for the ΔC* method which produce inventories five times lower in the Southern Ocean and 40% higher in the Artic Ocean. • Contemporary and preindustrial air-sea fluxes of natural and anthropogenic carbon remain uncertain in the Southern Ocean according to the quantification using an Ensemble Kalman Filter Assimilation into the Bern3D model • CANT inventory was 54 ±8 Pg C for the Atlantic Ocean for 1994 using 5 selected sections and a combination of the five methods. • Using the whole CARINA data for the Atlantic south 65ºN a total inventory of 55 PgC was obtained for 1994. • The temporal increase of CANT inventory between 1997 and 2003 (12%) follows that given by the atmospheric. • Strong reduction, of about three times, in the CANT inventory between high and low NAO scenarios in the Irminger Sea related with the water mass formation. • Temporal variation in the water mass formation in the North Atlantic has a very strong impact in the CANT storage rates.