Modelling marine carbon cycle more realistically Within the context of ORFOIS project, the Hamburg Model of the Ocean Carbon Cycle (HAMOCC3) model encompassing glacial oceanic circulation and dust input fields has become more reliable and realistic. Climate Change and Environment © DigitalVision As dictated by environmental protection policies, the establishment of reliable marine CO2 source/sink distributions along with their spatio-temporal prediction is of strategic importance for European countries. Carbon cycle research is expected to provide great assistance to mitigation of problems related to the rising CO2 atmospheric emissions. Additionally, precise quantification of marine particle flux dynamics could also allow for a more reliable prediction of the fate of hazardous materials in the marine domain. The ORFOIS project focused on the origin and fate of biogenic particle fluxes in the ocean and their interaction with the atmospheric CO2, as well as the marine sediment. Part of the project objectives included the development of a refined particle flux model for operational use in ocean general circulation models. The improved model needs to realistically describe particle dynamics in the water column, deposition of material to the sediment and the interaction with the partial pressure of CO2 (pCO2). On the basis of the HAMOCC3 model, project researchers included both the open and the closed system components that constitute the marine carbon cycle. The open system component comprises Aeolian dust and fluvial CaCO3 input and subsequent burial and dissolution of CaCO3 in the sediment. The closed system component involves the biological and counter pumps, as well as, the internal redistribution by oceanic circulation. Compared to other state-of-the-art closed system models, the newly improved model is more realistic and more sensitive to changes in the potential driving mechanisms for glacial pCO2 reduction. Glacial forcing results in a decrease of total CO2, increase of total alkalinity and decrease of PO4 in the oceans. It is expected that atmospheric pCO2 potentially falls at 230ppm approximately after several thousands years of integration. The identification and installation of a crucial and efficient mechanism to lower pCO2 may aid the already unexplored control mechanisms for glacial/ interglacial pCO2 changes.
