EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Drivers of the air-sea CO2 flux variability in the North Sea

Feifei Liu, Corinna Schrum, and Ute Daewel
Feifei Liu et al.
  • Helmholtz-Zentrum hereon, Institute of Coastal Systems-Analysis and Modeling, Germany (

Identifying the mechanisms driving the variability of the air-sea exchange of carbon dioxide (CO2) in the North Sea is necessary to evaluate the consequences of human interventions such as coastal alkalinity enhancement (OAE) on this societally important ecosystem. For this purpose, the three-dimensional coupled physical-biological model SCHISM-ECOSMO, encompassing a carbonate chemistry module, is employed to present the local physical-biogeochemical processes as well as the exchange processes across scales and compartments. Here we present model results for a 5-year simulation (2002-2004), which are shown to agree well with the observations, indicating a net CO2 uptake in the northern North Sea (NNS) over the year while a net source of CO2 to the air in summer in the southern North Sea (SNS). In the NNS, the ‘Continental Shelf Pump’ mechanism, attributing to the seasonal stratification and efficient carbon export, determines the CO2 exchange, making the ocean a net sink despite the high temperature in summer that contributes to an enhancement of the CO2 release. In contrast, the temperature-driven release of CO2 outcompetes the biological CO2 drawdown in the shallower SNS. In this region, the tidal mixing prevents seasonal stratification. As a result, the CO2 generated via remineralization gets quickly in contact with the atmosphere. In addition, the interannual variability of the CO2 flux is assessed based on the 5-year simulation, which is mainly associated with the variations of the hydrodynamic conditions and productions induced by changes of meteorological conditions.

How to cite: Liu, F., Schrum, C., and Daewel, U.: Drivers of the air-sea CO2 flux variability in the North Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3634,, 2022.