1Centre for Isotope Research (CIO), University of Groningen, Groningen, the Netherlands
2Max Planck Institute for Biogeochemistry, Jena, Germany
*currently at: CIRCE, Department of Environmental Sciences, Second University of Napels, Caserta, Italy
**currently at: Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
Abstract. We report results from our atmospheric flask sampling network for three European sites: Lutjewad in the Netherlands, Mace Head in Ireland and the North Sea F3 platform. The air samples from these stations are analyzed for their CO2 and O2 concentrations. In this paper we present the CO2 and O2 data series from these sites between 1998 and 2009, as well as the atmospheric potential oxygen (APO). The seasonal pattern and long term trends agree to a large extent between our three measurement locations. We however find a changing gradient between Mace Head and Lutjewad, both for CO2 and O2. To explain the potential contribution of fossil fuel emissions to this changing gradient we use an atmospheric transport model in combination with CO2 emission data and information on the fossil fuel mix per region. Using the APO trend from Mace Head we obtain an estimate for the global oceanic CO2 uptake of 1.8 ± 0.8 PgC/year.