The impacts of eutrophication and biological feedbacks on the variability of the carbon shelf pump in the North Sea from 1970 to 2006

ECOHAM4, a 3D coupled biogeochemical-physical ecosystem model for the North Sea (511,725 km), was used to generate a hindcast from 1970-2006 for the Northwest European Shelf (47 41‘ – 63 53’ N, 15 5’ W – 13 55’ E) to analyze the carbon budgets and the variability of the transport of atmospheric carbon via biological fixation into the North Atlantic. Together with the lateral advection and the vertical export of carbon, this process is often referred to as the carbon shelf pump. The model treats, partly decoupled, the marine carbon cycle, the nutrient cycles for N, P and Si, oxygen, two phytoplankton and two zooplankton groups as well as marine bacteria and detritus. A set of forcings is included, among others 6-hourly meteorological fields by NCEP reanalysis, annual atmospheric nitrogen deposition (EMEP) and daily riverine input of nutrients and carbon.