Carbon dioxide dynamics and air-sea CO2 fluxes in the SES : Synthesis of the SESAME cruises

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Carbon dioxide dynamics and air-sea CO

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fluxes in the SES : Synthesis of the SESAME cruises

A.V. Borges (ULg-MARE, alberto.borges@ulg.ac.be), M.-V. Commarieu (ULg-MARE), E. Ozsoy

(METU), S. Sancak (METU), S. Tugrul (METU), N. Yücel (METU), Z. Uysal (METU), E. Krasakopoulou

(HCMR), E. Hurtas (ICMAN-CSIC), G. Catalano (CNR-ISA), A. Luchetta (CNR-ISA), C. Goyet (Univperp)

CIESM Congress, 10-14 May 2010

• In the frame of the European Integrated Project “Southern European Seas: Assessing and Modelling Ecosystem changes” (SESAME), two sets of cruises were carried out in spring and fall 2008 to cover all of the Southern European Sea (SES) regions. Here, we report on the

dynamics in surface waters of the partial pressure of CO2

(pCO2) either measured directly by equilibration or

computed from pH and total alkalinity.

• Sea surface temperature (SST) ranged between 12°C in the Black Sea in spring to 29°C in the Cilician basin in fall. In all the SES regions SST increased from spring to fall, on average by 8.0°C, ranging between 6°C (Alboran) to 11°C (Cilician).

• pCO2at in-situ temperature (pCO2@SST) ranged from 260

ppm in the Black Sea in fall to 450 ppm in the Cilician

bassin in fall. In most the SES regions pCO2@SST

increased from spring to fall, except in the Adriatic

(pCO₂@SST ± stable, despite large spatial variability (not

shown)) and except in the Black Sea (decrease of

pCO2@SST)

• Since an increase of 8°C in SST leads to an increase of

pCO2 of 145 ppm we normalized the pCO2 data to a

temperature of 20°C (pCO2@20°C). pCO2@20°C ranged

from 540 ppm in spring to 270 ppm in fall in the Black Sea. In the Adriatic, Aeagean, Black Sea, Cilician, Levantine,

pCO2@20°C decreased from spring to fall, indicating a

cumulated drawdown of CO2by biological activity. In the

Alboran pCO2@20°C increased from spring to fall possibly

indicative of upwelling (in agreement with a lesser increase of SST from spring to fall than the other SES regions). In

the Maramara Sea, pCO2@20°C increased from spring to

fall due to a strong decline in primary production (not shown).

• Air-sea CO2fluxes ranged from -5.7 mmolC m-2d-1in the

Black Sea in fall to +2.5 mmolC m-2 _d-1 _{in the Cilician}

bassin in fall. In Spring, all the SES regions were sinks for

atmospheric CO2. In fall, the more « open » SES areas were

sources of atmospheric CO2(Alboran, Levantine, Cilician &

Aegean). In fall, the more « coastal » SES areas remained

sinks for atmospheric CO2(Adriatic, Marmara, Black Sea),

but only in the Black Sea the CO2sink increased in fall.

Alboran Sea - SST (°C) 10.0 15.0 20.0 25.0 30.0 Levantine - SST (°C) 10.0 15.0 20.0 25.0 30.0 Cilician - SST (°C) 10.0 15.0 20.0 25.0 30.0 Marmara - SST (°C) 10.0 15.0 20.0 25.0 30.0 Black Sea - SST (°C) 10.0 15.0 20.0 25.0 30.0 Aegean - SST (°C) 10.0 15.0 20.0 25.0 30.0 Adriatic - SST (°C) 10.0 15.0 20.0 25.0 30.0 Spring Fall

Spring Fall SpringSpring FallFall SpringSpring FallFall

Spring Fall

Alboran Sea - pCO2@SST

250 300 350 400 450 500

Adriatic Sea - pCO2@SST

250 300 350 400 450 500

Aegean Sea - pCO2@SST

250 300 350 400 450 500 Levantine - pCO2@SST 250 300 350 400 450 500 Cilician - pCO2@SST 250 300 350 400 450 500 Marmara - pCO2@SST 250 300 350 400 450 500

Black Sea - pCO2@SST

250 300 350 400 450 500 Spring Fall

Spring Fall

Alboran Sea - pCO2@20°C

250 300 350 400 450 500 550 Levantine - pCO2@20°C 250 300 350 400 450 500 550 Cilician - pCO2@20°C 250 300 350 400 450 500 550 Marmara - pCO2@20°C 250 300 350 400 450 500 550

Black Sea - pCO2@20°C

250 300 350 400 450 500 550

Aegean Sea - pCO2@20°C

250 300 350 400 450 500 550

Adriatic Sea - pCO2@20°C

250 300 350 400 450 500 550 Spring Fall

Spring Fall

Alboran Sea - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6

Levantine - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6

Cilician - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6

Marmara - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6

Black Sea - air-sea CO2 flux (mmol m-2_d-1₎ -6 -4 -2 0 2 4 6 Aegean - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6 Adriatic - air-sea CO2 flux

(mmol m-2_d-1₎ -6 -4 -2 0 2 4 6 Spring Fall

Spring Fall