EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seasonal and spatial variability of the CO2 system parameters in the Northeast Atlantic based on measurements from a surface ocean observation platform.

David Curbelo Hernández1, Melchor González Dávila1, Aridane González González1, David González Santana1,2, and Juana Magdalena Santana Casiano1
David Curbelo Hernández et al.
  • 1Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, 35017, Spain.
  • 2Univ Brest, CNRS IRD, IFREMER, LEMAR, F-29280 Plouzané, France.

The seasonal and spatial variability of the CO2 system parameters and CO2 air-sea exchange was studied in the Northeast Atlantic Ocean between the northwest African coastal upwelling and the oligotrophic open-ocean waters of the North Atlantic subtropical gyre. Data was collected aboard a volunteer observing ship (VOS) from February 2019 to February 2020. The seasonal and spatial variability of CO2 fugacity in seawater (fCO2,sw) was strongly driven by the seasonal temperature variation, which increased with latitude and was lower throughout the year in coastal regions where the upwelling and offshore transport was more intense. The thermal to biological effect ratio (T/B) was approximately 2, with minimum values along the African coastline related to higher biological activity in the upwelled waters. The fCO2,sw increased from winter to summer by 11.84 ± 0.28 µatmºC-1 on the inter-island routes and by 11.71 ± 0.25 µatmºC-1 along the northwest African continental shelf. The seasonality of total inorganic carbon (CT) normalized to constant salinity of 36.7 (NCT) was studied throughout the region. The effect of biological processes and calcification/dissolution on NCT between February and October represented >90% of the reduction of inorganic carbon while air-sea exchange described <6%. The seasonality of air-sea CO2 exchange was controlled by temperature. The surface waters of the entire region acted as a CO2 sink during the cold months and as a CO2 source during the warm months. The Canary basin acted as a net sink of -0.26 ± 0.04 molC m-2 yr-1. The northwest African continental shelf behaved as a stronger sink at -0.48 ± 0.09 molC m-2 yr-1. The calculated average CO2 flux for the entire area was -2.65 ± 0.44 TgCO2 yr-1 (-0.72 ± 0.12 TgC yr-1).

How to cite: Curbelo Hernández, D., González Dávila, M., González González, A., González Santana, D., and Santana Casiano, J. M.: Seasonal and spatial variability of the CO2 system parameters in the Northeast Atlantic based on measurements from a surface ocean observation platform., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12710,, 2021.

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