ICES Journal of Marine Science: Journal du Conseil Advance Access originally published online on April 17, 2009
ICES Journal of Marine Science: Journal du Conseil 2009 66(7):1538-1546; doi:10.1093/icesjms/fsp049
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This article appears in the following ICES Journal of Marine Science issue: Effects of Climate Change on the World's Oceans [View the issue table of contents]
Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach
1 Ecole Nationale Supérieure des Sciences de la Mer et de l’Aménagement du Littoral (ex-ISMAL), Bois des cars, Dely-Brahim, 16320 Algiers, Algeria
2 Office National de la Météorologie (ONM), Dar El Beida, Algiers, Algeria
Correspondence: F. Louanchi: tel/fax: +213 21 91 77 90; e-mail: lairef{at}hotmail.com
Louanchi, F., Boudjakdji, M, and Nacef, L. 2009. Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach. – ICES Journal of Marine Science, 66: 1538–1546.A coupled approach based on available datasets of temperature, salinity, oxygen, nutrients, and chlorophyll, and a surface layer box model previously developed and modified for the present study, allowed us to reconstruct dissolved inorganic carbon (DIC), total alkalinity, and carbon dioxide fugacity (fCO2) mixed-layer fields for the Mediterranean Sea, from the 1960s to the 1990s. The approach used in this study resulted in a 7% relative error on reconstructed surface fCO2 fields. The Mediterranean Sea transformed from a source of 0.62 Tg C year–1 for atmospheric CO2 in the 1960s, to a net sink of –1.98 Tg C year–1 in the 1990s. The annual cycle in surface fCO2 was driven mainly by temperature variations in the Mediterranean Sea, whereas its decadal variations resulted from a balance between primary production and the thermal effect. According to our model results, the atmospheric CO2 increase of
40 µatm over the period of our investigation induced an increase in DIC of 30 µmol l–1 in surface waters. A 50% reduction in the magnitude of seasonal variations in surface temperature occurred during the 1990s relative to the earlier decades. Therefore, surface fCO2 only increased by 24 µatm from the 1960s to the 1990s. Changes in pH were not significant over this period.
Keywords: air–sea CO2 fluxes, carbon dioxide, decadal variability, exported production, Mediterranean Sea, primary production
Received 15 August 2008; accepted 8 February 2009; advance access publication 17 April 2009.