Is the southern North Sea a carbon source or sink? : a model-data integration exercise

The role of continental shelves in carbon sequestration is poorly quantified. Riverine inputs present terrestrial inputs of organic carbon and nutrients to the coastal zone. In addition, the strong benthic-pelagic coupling in shallow areas, combined with the large variation in hydrodynamic and hydrographic regimes puts a large uncertainty on vertical carbon export fluxes. Furthermore, ocean-atmosphere interactions close to land are strongly influenced by local conditions such as wind direction and bottom depth, which are key determinants for wave conditions and gas exchange. We use a relatively simple 1D vertical ecosystem model in concert with monitoring data from national monitoring programmes and the ICOS project (Integrated Carbon Observing System; EU infrastructure project) to identify and quantify sources of uncertainty in carbon export fluxes in the southern North Sea. Results are discussed against a background of coastal and latitudinal gradients.