Short-term variability of surface carbon dioxide and sea-air CO2 fluxes in the shelf waters of the Galician coastal upwelling system


  • Alba Marina Cobo-Viveros Instituto de Investigacións Mariñas (IIM-CSIC)
  • Xosé Antonio Padin Instituto de Investigacións Mariñas (IIM-CSIC)
  • Pablo Otero Instituto Español de Oceanografía (IEO)
  • Mercedes de la Paz Instituto de Investigacións Mariñas (IIM-CSIC)
  • Manuel Ruiz-Villarreal Instituto Español de Oceanografía (IEO)
  • Aida F. Ríos Instituto de Investigacións Mariñas (IIM-CSIC)
  • Fiz F. Pérez Instituto de Investigacións Mariñas (IIM-CSIC)



carbon dioxide, coastal upwelling, sea-air gas exchanges, carbon sinks


Using data collected during the DYBAGA and ECO cruises, remote sensing chlorophyll-a estimations and the averaged upwelling index of the previous fortnight (Iw’), we studied the variability of the sea surface CO2 fugacity (fCO2) over the Galician continental shelf during three seasonal cycles. Sea surface salinity (SSS) distribution controlled fCO2 mainly in spring, while sea surface temperature (SST) did so during periods of intense cooling in November and warming in June. The uptake of carbon by photosynthetic activity, which was more intense during spring and autumn, masked the surface increase in the dissolved inorganic carbon concentration during upwelling events, especially during spring. A significant low correlation between fCO2 and Iw’ was found during spring and summer when upwelling events were observed, whereas no relationship was observed during the downwelling period. High fCO2 exceeding atmospheric values was only found during the summer stratification breakdown. Although sea-air CO2 fluxes showed a marked inter-annual variability, surface waters off the Galician coast were net sinks for atmospheric CO2 in every seasonal cycle, showing a lower CO2 uptake (~65%) compared to previously published values. Marked inter-annual changes in the sea-air CO2 fluxes seem to be influenced by fresh water inputs on the continental shelf under different meteorological scenarios.


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Álvarez I., Ospina-Álvarez N., Pazos Y., DeCastro M., Bernardez P., Campos M.J., Gómez-Gesteira J.L., Alvarez-Ossorio M.T., Varela M., Gomez-Gesteira M., Prego R. 2009. A winter upwelling event in the Northern Galicia Rias: frequency and oceanographic implications. Est. Coast. Shelf Sci. 82 (4): 573-582.

Álvarez-Salgado X.A., Rosón G., Pérez F. F., Pazos Y. 1993. Hydrographic variability off the Rías Baixas (NW Spain) during the upwelling season. J. Geophys. Res. 98(C8): 14447-14455.

Álvarez-Salgado X.A., Doval M.D., Borges A.V, Joint I., Frankignoulle M., Woodward E.M.S., Figueiras F.G. 2001. Off-shelf fluxes of labile materials by an upwelling filament in the NW Iberian Upwelling System. Prog. Oceanogr. 51(2-4): 321-337.

Álvarez-Salgado X.A., Beloso S., Joint I., Nogueira E., Chou L., Pérez F.F., Groom S., Cabanas J.M., Rees A.P., Elsken V. 2002. New production of the NW Iberian shelf during the upwelling season over the period 1982-1999. Deep-Sea Res. Part I 49(10): 1725-1739.

Arístegui J., Barton E.D., Tett P., Montero M.F., García-Muñoz M., Basterretxea G., Cussatlegras A.S., Ojeda A., de Armas D. 2004. Variability in plankton community structure, metabolism, and vertical carbon fluxes along an upwelling filament (Cape Juby, NW Africa). Prog. Oceanogr. 62 (2-4): 95-113.

Arístegui J., Barton E.D., Álvarez-Salgado X.A., Santos A.M.P., Figueiras F.G., Kifani S., Hernández-León S., Mason E., Machú E., Demarcq H. 2009. Sub-regional ecosystem variability in the Canary Current upwelling. Prog. Oceanogr. 83(1-4): 33-48.

Bakun A., Nelson C.S. 1991. The seasonal cycle of wind-stress curl in subtropical eastern boundary current regions. J. Phys. Oceanogr. 21(12): 1815-1834.<1815:TSCOWS>2.0.CO;2

Barton E.D., Inall M.E., Sherwin T.J., Torres R. 2001. Vertical structure, turbulent mixing and fluxes during Lagrangian observations of an upwelling filament system off Northwest Iberia. Prog. Oceanogr. 51(2-4): 249-267.

Blanton J.O., Atkinson L.P., de Castillejo F.F., Lavín A. 1984. Coastal upwelling off the Rías Bajas, Galicia, northwest Spain. In: International Council for the Exploration of the Sea. Hydrographic Studies. Rapp. p-v Reun. 183: 79-90.

Borges A.V. 2005. Do we have enough pieces of the jigsaw to integrate CO2 fluxes in the Coastal Ocean? Estuaries 28(1): 3-27.

Borges A.V., Frankignoulle M. 2001. Short-term variations of the partial pressure of CO2 in surface waters of the Galician upwelling systeym. Prog. Oceanogr. 51(2-4): 283-302.

Borges A.V., Frankignoulle M. 2002. Distribution of surface carbon dioxide and air-sea exchange in the upwelling system off the Galician coast. Global Biogeochem. Cycles 16(2): 1020.

Borges A.V., Delille B., Frankignoulle M. 2005. Budgeting sinks and sources of CO2 in the coastal ocean: diversity of ecosystems counts. Geophys. Res. Lett. 32: L14601.

Castro C.G., Alvarez-Salgado X.A., Figueiras F.G., Pérez F.F., Fraga F. 1997. Transient hydrographic and chemical conditions affecting microplankton populations in the coastal transition zone of the Iberian upwelling system (NW Spain) in September 1986. J. Mar. Res. 55(2): 321-352.

Chen C.T.A., Borges A.V. 2009. Reconciling opposing views on carbon cycling in the coastal ocean: continental shelves as sinks and near-shore ecosystems as sources of atmospheric CO2. Deep-Sea Res. Part II 56(8-10): 578-590.

Dickson A.G., Sabine C.L., Christian J.R. (eds). 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp.

Fraga F. 1981. Upwelling off the Galician coast, northwest Spain. Coastal Upwelling, American Geophysical Union, Washington DC, pp. 176-182.

Fraga F., Mouriño C., Manriquez M. 1982. Las masas de agua en la costa de Galicia: junio-octubre. Result. Exped. Cient. Supl. Invest. Pesq. 10: 51-77.

Frankignoulle M., Abril G., Borges A., Bourge I., Canon C., Delille B., Libert E., Théate J.M. 1998. Carbon Dioxide Emission from European Estuaries. Science 282(5388): 434-436. PMid:9774261

Friederich G.E., Ledesma J., Ulloa, O., Chavez, F.P. 2008. Air-sea carbon dioxide fluxes in the coastal southeastern tropical Pacific. Prog. Oceanogr. 79(2-4): 156-166.

Frouin R., Fiúza A.F.G., Ambar I., Boyd T.J. 1990. Observations of a poleward surface current off the coasts of Portugal and Spain during winter. J. Geophys. Res. 95(C1): 679-691.

Gago J., Gilcoto M., Pérez F.F., Ríos A.F. 2003a. Short-term variability of fCO2 in seawater and air-sea CO2 fluxes in a coastal upwelling system (Ría de Vigo, NW Spain). Mar. Chem. 80(4): 247-264.

Gago J., Álvarez-Salgado X.A., Pérez F.F., Ríos A.F. 2003b. Partitioning of physical and biogeochemical contributions to short-term variability of pCO2 in a coastal upwelling system: a quantitative approach. Mar. Ecol. Prog. Ser. 255: 43-54.

Gypens N., Borges A.V., Lancelot C. 2009. Effect of eutrophication on air-sea CO2 fluxes in the coastal Southern North Sea: a model study of the past 50 years. Global Change Biol. 15(4): 1040-1056.

Haynes R., Barton E.D., Pilling I. 1993. Development, persistence, and variability of upwelling filaments off the Atlantic coast of the Iberian Peninsula. J. Geophys. Res. C 98(C12): 22681-22692.

Hidy G.M. 1972. A view of recent air-sea interaction research. Bull. Am. Meteorol. Soc. 53(11): 1083-1102.<1083:AVORAS>2.0.CO;2

Kalnay E., Kanamitsu M., Kistler R., Collins W., Deaven D., Gandin L., Iredell M., Saha S., White G., Woollen J., Zhu Y., Chelliah M., Ebisuzaki W., Higgins W., Janowiak J., Mo K. C., Ropelewski C., Wang J., Leetmaa A., Reynolds R., Jenne R., Joseph D. 1996. The NCEP/NCAR 40-Year Reanalysis Project. Bull. Am. Meteorol. Soc. 77(3): 437-471.<0437:TNYRP>2.0.CO;2

Lampitt R.S., Fahrbach E., Schneider B., Schneider R.R., Smith S.V., Toggweiller J.R., Watson A.J., Zeitschel B. 1995. Group report: Does upwelling have a significant influence on the global carbon cycle? In: Summerhayes C.P., Emeis K.C., Angel M.V., Smith R.L., Zeitschel B. (eds.), Upwelling in the Ocean. Modern Processes and Ancient Records. Chichester, UK, John Wiley and Sons, pp. 383-404.

Laruelle G.G., Dürr H.H., Slomp C.P., Borges A.V. 2010. Evaluation of sinks and sources of CO2 in the global coastal ocean using a spatially explicit typology of estuaries and continental shelves. Geophys. Res. Lett. 37: L15607.

Mackenzie F.T., Ver L.M.B., Lerman A. 1998. Coupled biogeochemical cycles of carbon, nitrogen, phosphorous and sulfur in the land–ocean–atmosphere system. In: Galloway J.N., Melillo J.M. (eds.), Asian Change in the Context of Global Climate Change. Cambridge University Press, Cambridge, pp. 42-100.

Mackenzie F.T., Ver L.M., Lerman. A. 2000. Coastal-zone biogeochemical dynamics under global warming. Int. Geol. Rev. 42(3): 193-206.

Maritorena S., Siegel D.A. 2005. Consistent merging of satellite ocean color data sets using a bio-optical model. Remote Sens. Environ. 94(4): 429-440.

Muller-Karger F.E., Varela R., Thunell R., Luerssen R., Hu C., Walsh J.J. 2005. The importance of continental margins in the global carbon cycle. Geophys. Res. Lett. 32: L01602.

Ono T., Saino T., Kurita N., Sasaki K. 2004. Basin-scale extrapolation of shipboard pCO2 data by using satellite SST and Chla. Int. J. Remote Sens. 25(19): 3803-3815.

Otero P., Ruiz-Villarreal M., Peliz A. 2008. Variability of river plumes off Northwest Iberia in response to wind events. J. Mar. Sys. 72(1-4): 238-255.

Otero P., Ruiz-Villarreal M., Peliz A., Cabanas J.M. 2010. Climatology and reconstruction of runoff time series in northwest Iberia: influence in the shelf buoyancy budget off Ría de Vigo. Sci. Mar. 74(2): 247-266.

Padin X.A., Navarro G., Gilcoto M., Rios A.F., Pérez F.F. 2009 Estimation of air-sea CO2 fluxes in the Bay of Biscay based on empirical relationships and remotely sensed observations. J. Mar. Syst. 75(1-2): 280-289.

Padin X.A., Vázquez-Rodríguez M., Castaño M., Velo A., Alonso- Pérez F., Gago J., Gilcoto M., Álvarez M., Pardo P.C., de la Paz M., Ríos A.F., Pérez F.F. 2010. Air-Sea CO2 fluxes in the Atlantic as measured during boreal spring and autumn. Biogeosciences 7: 1587-1606.

Pauly D., Christensen V. 1995. Primary production required to sustain global fisheries. Nature 374(6519): 255-257.

Pérez F.F., Ríos A.F., Rosón G. 1999. Sea surface carbon dioxide off the Iberian Peninsula (North Eastern Atlantic Ocean). J. Mar. Sys. 19(1-3): 27-46.

Pérez F.F., Padin X.A., Pazos Y., Gilcoto M., Cabanas M., Pardo P.C., Doval M.D., Farina-Busto L. 2010. Plankton response to weakening of the Iberian coastal upwelling. Global Change Biol. 16(4): 1258-1267.

Pierrot D., Neill C., Sullivan K., Castle R., Wanninkhof R., Lüger H., Johannessen T., Olsen A., Feely R.A., Cosca C.E. 2009. Recommendations for autonomous underway pCO2 measuring systems and data reduction routines. Deep-Sea Res. Part II 56(8-10): 512-522.

Pingree R.D., Le Cann B. 1990. Structure, strength and seasonality of the slope currents in the Bay of Biscay region, J. Mar. Biol. Assoc. U.K. 70(4): 857-885.

Rabouille C., Mackenzie F.T., Ver L.M. 2001. Influence of the human perturbation on carbon, nitrogen, and oxygen biogeochemical cycles in the global coastal ocean. Geochim. Cosmochim. Acta 65 (21): 3615-3641.

Ríos A.F., Pérez F.F., Fraga F. 1992. Water masses in the upper and middle North Atlantic Ocean east of the Azores. Deep-Sea Res. Part A 39(3-4): 645-658.

Ruiz-Villarreal M., González-Pola C., Diaz del Río G., Lavin A., Otero P., Piedracoba S., Cabanas J.M. 2006. Oceanographic conditions in North and Northwest Iberia and their influence on the Prestige oil spill. Mar. Pollut. Bull. 53(5-7): 220-238. PMid:16698046

Stephens M.P., Samuels G., Olson D.B., Fine R.A., Takahashi T. 1995. Sea-air flux of CO2 in the North Pacific using shipboard and satellite data. J. Geophys. Res. 100(C7): 13571-13583.

Takahashi T., Olafsson J., Goddard J.G., Chipman D.W., Sutherland S.C. 1993. Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: a comparative study. Global Biogeochem. Cycles 7(4): 843-878.

Takahashi T., Sutherland S.C., Sweeney C., Poisson A., Metzl N., Tilbrook B., Bates N., Wanninkhof R., Feely R.A., Sabine C., Olafssong J., Nojiri Y. 2002. Global sea-air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects. Deep-Sea Res. Part II 49 (9-10): 1601-1622.

Taylor A.H., Watson A.J., Robertson J.E. 1992. The influence of the spring phytoplankton bloom on carbon dioxide and oxygen concentrations in the surface waters of the northeast Atlantic during 1989. Deep-Sea Res. Part A. 39(2): 137-152.

Tomczak M., Godfrey J.S. 2003. Regional oceanography: an introduction. 2nd edition. Daya Publishing House, Delhi. PMCid:1851156

Tsunogai S., Watanabe S., Sato T. 1999. Is there a "continental shelf pump" for the absorption of atmospheric CO2? Tellus Series B 51(3): 701-712.

U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center. 2006. 2-minute Gridded Global Relief Data (ETOPO2v2).

Walsh J.J. 1991. Importance of continental margins in the marine biogeochemical cycling of carbon and nitrogen. Nature 350(6313): 53-55.

Wanninkhof R. 1992. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res. 97(C5): 7373-7382.

Weiss R.F. 1974. Carbon dioxide in water and seawater: the solubility of a non-ideal gas. Mar. Chem. 2(3): 203-215.

Weiss R.F., Price B.A. 1980. Nitrous oxide solubility in water and seawater. Mar. Chem. 8(4): 347-359.

Wooster W.S., Bakun A., Mclain. D.R. 1976. The seasonal upwelling cycle along the eastern boundary of the North Atlantic. J. Mar. Res. 34(2): 131-141.




How to Cite

Cobo-Viveros AM, Antonio Padin X, Otero P, de la Paz M, Ruiz-Villarreal M, Ríos AF, Pérez FF. Short-term variability of surface carbon dioxide and sea-air CO2 fluxes in the shelf waters of the Galician coastal upwelling system. scimar [Internet]. 2013Mar.30 [cited 2022Jul.4];77(S1):37-48. Available from: