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

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

METHODS

Vazquez-Rodriguez et al., 2009

ΔC* = 1.3 Pg C

South of 45ºS

TrOCA,TTD,φCtº,CºIPSL

5.5, 6.1 6.3 8.0 Pg C

ΔC* inventory 5 times lower

METHODS

Gerber and Joos, 2009

A detailed quantification of air-sea fluxes of natural and anthropogeniccarbon and their uncertainties by an Ensemble Kalman Filter Assimilationinto the Bern3D model

Contemporary and preindustrial fluxes remain uncertain in the Southern Ocean

ATLANTIC CANT INVENTORY

CANT inventory average 54 ±8 Pg C (for 1994)in the Atlantic Ocean from 65ºN to Antarctic

Vázquez et al., 2009

ATLANTIC CANT INVENTORY USING CARINA

Velo et al., in revision

CARINA WOA05

Developing of a multiparametric interpolation method

CANT inventory 55 ±6 Pg C (for 1994)in the Atlantic Ocean from 65ºN to Antarctic

ATLANTIC CANT INVENTORY USING CARINA

The temporal increase of CANT inventory between 1997 and 2003 (12%) follows that given by the atmosphere

Steinfeldt et al., in preparation

CANT inventory51 ±15 Pg C (for 1997)57 ±16 Pg C (for 2003)in the Atlantic Ocean south of 65ºN VR5.4% correction from 1994-1997(50.6 Pg C)

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

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)

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

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 rates were 1.32±0.11 and 1.18±0.16 mol C·m-2·y-1, respectively

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

REGIONAL CANT STORAGES

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

Cant in A-17 WOCE section

20

30

40

50

60

70

80

90

-50 -40 -30 -20 -10 0 10 20Lat (ºN)

Spec

ific

Inve

ntor

y (m

ol/m

2)

GLODAP

phi-Cº

TROCA

TTD

Lee et al.'03

Rios et al., to be submitted

TEMPORAL VARIATION OF CANT Steinfeldt et al., in preparation

Temporal variation in the water mass formation in the North Atlantic has a very strong impact in the CANT storage rates.

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 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

Basin NAO Phase (time period)

Cant Specific Inventory Rates (mol C m-2 yr-1)

Storage Rate (kmol s-1)

Storage Rate (Gt yr-1)

High (1991-1997) 1.74±0.24 34±5 0.013±0.002 Irminger Low (1997-2006) 0.4±0.3 8±6 0.006±0.002 High (1991-1998) 1.88±0.45 57±14 0.022±0.005

Iceland Low (1997-2006) 0.3±0.2 9±6 0.0035±0.003

ENA (1981-2006) 0.72±0.03 51±2 0.019±0.001

High NAO 4.3±0.6 142±15 0.054±0.006 TOTAL (OVIDE

BOX)

Low NAO 1.4±0.2 68±9 0.026±0.003

TEMPORAL VARIATION OF CANT

Pérez et al., see poster

The storage rates (±std. err. of the estimate)

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.

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.