Sea water fugacity of CO2 at the PIRATA mooring at 6°S, 10°W

Gaëlle Parard; Nathalie Lefèvre; Jacqueline Boutin

doi:10.1111/j.1600-0889.2010.00503.x

Sea water fugacity of CO2 at the PIRATA mooring at 6°S, 10°W

Tellus B: Chemical and Physical Meteorology

Volume 62 (2010): Issue 5

By: Gaëlle Parard, Nathalie Lefèvre and Jacqueline Boutin

Open Access

|Jan 2010

Abstract

In order to better understand the variability of surface CO₂ in the Tropical Atlantic, a CARIOCA sensor has been installed on a PIRATA mooring at 6°S, 10°W in June 2006. The fugacity of CO₂ (fCO₂) is recorded hourly from 7 June 2006 to 30 October 2009 with two important data gaps. From July to September, an upwelling develops and a decrease in sea surface temperature (SST) is observed, associated with an fCO₂ increase. However, the highest fCO₂ is observed in October, after the upwelling season, due to the warming of surface waters. The region is a net source of CO₂ to the atmosphere of 2.10 ± 0.69 mol m_-2 yr^-1 in 2007. The monthly flux is maximum (3.21 ± 0.8mol m^-2 yr^-1) in November (averaged over 2006 and 2008). High frequency variability is observed throughout the time series but is particularly pronounced after the upwelling season. Biological and thermodynamic processes explain the diurnal variability. Dissolved inorganic carbon (DIC) is calculated from (alkalinity) TA and fCO₂ using an empirical TA—salinity relationship determined for the eastern equatorial Atlantic. Net community production (NCP) is calculated from DIC daily changes and ranges from 9 to 41 mmol m^-2 d^-1, which is consistent with previous measurements in this region.

References

Andrié , C. , Oudot , C. , Genthon , C. and Merlivat , L . 1986 . CO2 fluxes in the tropical Atlantic during FOCAL cruises . J. Geophys. Res . 91 , 11741 – 11755 .
Search in Google Scholar Back to article
Astor , Y ., Muller-Karger, E and Scranton , M. I. 2003. Seasonal and interannual variation in the hydrography of the Cariaco Basin: impli-cations for basin ventilation. Continental Shelf Res . 23 , 125 - 144 .
Search in Google Scholar Back to article
Astor , Y. M. , Scranton , M I. , Muller-Karger, E , Bohrer , R. and Garcia , J. 2005. fCO2 variability at the CARTAGO tropical coastal upwelling Time Series Station. Mar. Chem . 97 , 245 - 261 .
Search in Google Scholar Back to article
Bakker , D. C. , Echeto , J. , Boutin , J. and Merlivat , L. 2001. Variability of surface water fCO2 during seasonal upwelling in the equatorial Atlantic Ocean as observed by a drifting buoy. J. Geophys. Res . 106 , 9241 - 9253 .
Search in Google Scholar Back to article
Bakker , D. CE ., deBaar, H. J. W. and deJong, E. 1999. The dependence on temperature and salinity of dissolved inorganic carbon in East Atlantic surface waters. Mar Chem . 65 , 263 - 280 .
Search in Google Scholar Back to article
Bakun , A . 1978 . Guinea Current upwelling . Nature 271 , 147 – 150 .
Search in Google Scholar Back to article
Bates , N. R. , Michaels , A. E and Knap , A. H . 1996 . Seasonal and interannual variability of oceanic carbon dioxide species at the US JGOFS Bermuda Atlantic Time-series Study (BATS) site . Deep Sea Res. Part II: Topical Stud. Oceanogr . 43 , 347 – 383 .
Search in Google Scholar Back to article
Bates , N R. , Takahashi , T. , Chipman , D. W. and Knap , A. H. 1998. Variability of pCO2 on diel to seasonal timescales in the Sargasso Sea near Bermuda. Geophys. Res . 103 , 15567 - 15585 .
Search in Google Scholar Back to article
Bates , N R. , Merlivat , L. , Beaumont , L. and Pequignet , C. A. 2000. Intercomparison of shipboard and moored CARIOCA buoy seawater fCO2 measurement in Saragossa Sea. Mar Chem . 72 , 239 - 255 .
Search in Google Scholar Back to article
Bindoff , N. L. , Willebrand , J. , Artale , V. , Cazenave , A. , Gregory , J. and co-authors . 2007 . Observations: oceanic climate change and sea level. In: Climate Change: The Physical Science Basis. Contribution of working group I to the Fourth Assessment Report of the Intergouvemmental Panel on Climate Change (eds S. Solomon , D. Quin , M. Manning , Z. Chen , M. Marquis and co-authors ), Cambridge Uni-veristy Press , Cambridge, United Kingdom and New York, NY, USA , 385 - 432 .
Search in Google Scholar Back to article
Bourles , B. , Lumpkin , R. , Phaden , M. M. , Hernandez, E , Nobre , P. and co-authors . 2008 . THE PIRATA PROGRAM: history, Accom-plishments, and Future Directions. Bull. Am. MeteoroL Soc . 89 , 1111 - 1125 .
Search in Google Scholar Back to article
Boutin , J. and Merlivat , L. 2009. New in situ estimates of carbon biolog-ical production rates in the Southern Ocean from CARIOCA drifter measurements. Geophys. Res. Lett . 36 , 1 - 6 .
Search in Google Scholar Back to article
Boyer Montegut , C. , Madec , G. , Fischer , A. S. , Lazar , A. and Ludicone , D . 2004 . Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology . J. Geophys. Res . 109 , C12003 , doi: 10.1029/2004JC002378 .
Open DOI Search in Google Scholar Back to article
Byrne , R H. , Degrandpre , M. D. , Short , R. T. , Martz , T. R. , Merli-vat , L. and co-authors . 2009 . Sensors and systems for in situ ob-servations of marine CO2 system variables. In: Proceedings of the OceanObs09 , Venice, Italy, September 21-25, 2009. Available at: http://www.oceanobs09.net/.
Search in Google Scholar Back to article
Chavez , E. P. , Pennington , T. J. , Herlien , R. , Jannasch , J. H. , Thurmond , G. and co-authors . 1997 . Moorings and drifters for real-time interdis-ciplinary oceanography. Am. Meteorol. Soc . 14 , 1199 - 1211 .
Search in Google Scholar Back to article
Copin-Montegut , C. , Begovic , M. and Merlivat , L . 2004 . Variability of the partial pressure of CO2 on diel to annual time scales in the Northwestern Mediterranean Sea . Mar Chem . 85 , 169 – 189 .
Search in Google Scholar Back to article
Dickson , A. and Millero , E 1987 . A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media . Deep Sea Res. Part A. Oceanogr Res. Papers 34 , 1733 – 1743 .
Search in Google Scholar Back to article
Dufour , P. and Stretta , J. M . 1973 . Production primaire, biomasse du phytoplancton et du zooplancton dans l'Atlantique tropi-cal sud, le long du meridien 4°W . Ser Océanogr 11 , 419 – 429 .
Search in Google Scholar Back to article
Gonzalez-Ddvila , M ., Santana-Casiano , J. M. , Rueda , M. J. , Llinds , O. and Gonzalez-Da-Ala , E. E. 2003. Seasonal and interannual variability of sea-surface carbon dioxide species at the European Station for Time Series in the Ocean at the Canary Islands (ESTOC) between 1996 and 2000. Global Biogeochem. Cycles 17 , 1076 .
Search in Google Scholar Back to article
Hazeleger , W. , de Vries , P. and Friocourt , Y . 2003 . Sources of the equa-torial undercurrent in the Atlantic in a high-resolution ocean model . J. Phys. Oceanogr 33 , 677 – 693 .
Search in Google Scholar Back to article
Hood , E. M. and Merlivat , L . 2001 . Annual to interannual variations of fCO2 in the northwestern Mediterranean Sea: high frequency time series data from CARIOCA buoys (1995-1997) . J. Mar Res . 59 , 113 – 131 .
Search in Google Scholar Back to article
Koffi , U. , Lefevre , N. , Kouadio , G. and Boutin, J. 2010. Surface CO2 parameters and air-sea CO2 flux distribution in the eastern equatorial Atlantic. J. Mar SysL 82 , 135 - 144 .
Search in Google Scholar Back to article
Körtzinger , A . 2003 . A significant CO2 sink in the tropical Atlantic Ocean associated with the Amazon River plume . Geophys. Res. Lett . 30 , 2287 .
Search in Google Scholar Back to article
Körtzinger , A. , Send , U. , Wallace , D. W. R. , Karstensen , J. and DeGrandpre , M. 2008. Seasonal cycle of 02 and pCO2 in the central Labrador Sea: atmospheric, biological, and physical implications. Global Bio-geochem. Cycles 22 , 1 - 16 .
Search in Google Scholar Back to article
Lefevre , N . 2009 . Low CO2 concentrations in the Gulf of Guinea during the upwelling season in 2006 . Mar Chem . 113 , 93 – 101 .
Search in Google Scholar Back to article
Lefevre , N. , Ciabini , J. P. , Michard , G. , Briest , B. , Duchaffaut , M. and co-authors . 1993 . A new optical sensor for pCO2 measurement. Mar Chem . 42 , 189 - 198 .
Search in Google Scholar Back to article
Lefevre , N. , Moore , G. , Aiken , J. , Watson , A. and Cooper , D. 1998. Variability of pCO2 in tropical Atlantic in 1995. J. Geophys. Res . 103 , 5623 - 5634 .
Search in Google Scholar Back to article
Lefevre , N. , Guillot , A. , Beaumont , L. and Danguy , T . 2008 . Variability of fCO2 in the Eastern Tropical Atlantic from a moored buoy . J. Geophys. Res . 113 , 1 – 12 .
Search in Google Scholar Back to article
Lefevre , N. , Diverres , D. and Gallois , E 2010 . Origin of CO2 undersatu-rations in the western tropical Atlantic. Tellus B , doi: 10.1111/j.1600-0889.2010.00475.x .
Open DOI Search in Google Scholar Back to article
Leinweber , A. , Gruber , N. , Fenzel , H. , Friedeich , G. E. and Chavez , E. P. 2009. Diurnal carbon cycling in the surface ocean and lower atmosphere of Santa Monica Bay, California. Geophys. Res. Lett . 36 , 1 - 5 .
Search in Google Scholar Back to article
Merbach , C. , Culberson , C. H. and Hawley, J. E. 1973. Measurements of the apparent dissociation constants of carbonic acid in seawater of atmospheric pressure. Lymnol. Oceanogr 18 , 897 - 907 .
Search in Google Scholar Back to article
Merlivat , L. , Davila , M. , Caniaux , G. and Boutin, J. 2009. Mesoscale and diel to monthly variability of CO2 and carbon fluxes at the ocean surface in the northeastern Atlantic. J. Geophys. Res.-Oceans 114 , 1 - 17 .
Search in Google Scholar Back to article
Oudot , C. , Temon , J. and Lecomte , J. 1995. Measurements of atmo-spheric and oceanic CO2 in the tropical Atlantic: 10 years after the 1982-1984 FOCAL cruises. Tellus 47B , 70 - 85 .
Search in Google Scholar Back to article
Sayles , E L. and Eck , C . 2009 . An autonomous instrument for time series analysis of TCO2 from oceanographic moorings . Deep Sea Res. Part Oceanogr. Res. Papers 56 , 1590 – 1603 .
Search in Google Scholar Back to article
Send , U. , Weller , R. , Wallace , D. , Chavez , E , Lampitt , R. and co-authors . 2009 . OceanalES. In: Proceedings of the OceanObs09 , Venice, Italy, September 21-25,2009. Available at: http://www.oceanobs09.net/.
Search in Google Scholar Back to article
Stramma , L. and Schott , E 1999 . The mean flow field of the tropical Atlantic Ocean. Deep-sea Res. 11 46 , 279 - 303 .
Search in Google Scholar Back to article
Sweeney , C. , Gloor , E. , Jacbson , A. R. , Key , R. M. , McKinley , M. and co-authors . 2007 . Constrainning global air-sea gas exchange for CO2 with recent bomb 14C measurements. Global Biogeochim. Cycles 21 , 1 - 10 .
Search in Google Scholar Back to article
Takahashi , T. , Olafsson , J. , Goddard , J. G. , Chipman , D. W. and Suther-land , S. C . 1993 . Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: a comparative study . Global Biogeochem. Cycles 7 , 843 – 878 .
Search in Google Scholar Back to article
Takahashi , T. , Sutherland , S. C. , Wanninkhof , R. , Sweeney , C. , Feely , R. A. and co-authors . 2009 . Climatological mean and decadal change in surface ocean pCO2, and net sea—air CO2 flux over the global oceans. Deep-Sea Res. Part 11 56 , 554 - 577 .
Search in Google Scholar Back to article
Temon , J. , Oudot , C. , Dessier , A. and Diverres , D. 2000. A sea-sonal tropical sink for atmospheric CO2 in the Atlantic Ocean: the role of the Amazon River discharge. Mar Chem . 68 , 183 - 201 .
Search in Google Scholar Back to article
Torrence , C. and Compo , G. P . 1998 . A practical guide to wavelet anal-ysis . Bull. Am. MeteoroL Soc . 79 , 61 – 78 .
Search in Google Scholar Back to article
Voituriez , B. and Herbland , A . 1979 . The use of the salinity maximum of the Equatorial Undercurrent for estimating nutrient enrichment and primary production in the Gulf of Guinea . Deep Sea Res. Part A. Oceanogr Res. Papers 26 , 77 – 83 .
Search in Google Scholar Back to article
Voituriez , B. and Herbland , A . 1982 . Primary production in the Tropical Atlantic ocean mapped from oxygen values of equalant 1 and 2 ( 1963 ). Bull. Mar Sci . 31 , 853 – 863 .
Search in Google Scholar Back to article
Weiss , R. E 1974 . CO2 in water and seawater: the solubility of a non ideal gas . Mar. Chem . 2 , 203 – 215 .
Search in Google Scholar Back to article
Weiss , R. E and Price , B. A . 1980 . Nitrous oxide solubility of a non ideal gas . Mar. Chem . 8 , 347 – 359 .
Search in Google Scholar Back to article

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DOI: https://doi.org/10.1111/j.1600-0889.2010.00503.x | Journal eISSN: 1600-0889

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Language: English

Page range: 636 - 648

Submitted on: Dec 22, 2009

Accepted on: Aug 6, 2010

Published on: Jan 1, 2010

Published by: Stockholm University Press

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© 2010 Gaëlle Parard, Nathalie Lefèvre, Jacqueline Boutin, published by Stockholm University Press
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Volume 62 (2010): Issue 5