Changes of anthropogenic CO2 and CFCs in the North Atlantic between 1981 and 2004

摘要

We compare total dissolved inorganic carbon (DIC) and chlorofluorocarbon (CFC) measurements in the northwest Atlantic made during the Transient Tracers in the Ocean, North Atlantic Study (TTO-NAS) in 1981 with modern measurements from a cruise in 2004. The observed changes in the DIC and CFC fields are compared to those predicted from an eddy-permitting ocean circulation model. The rapid, but time-variable, atmospheric CFC increase in relation to the relatively steady anthropogenic CO2 increase influences the relationship between the observed uptake of DIC and CFC. We demonstrate the importance of ocean mixing in the calculation of anthropogenic CO2 (C-ant) based on transient tracer data by comparing our observations to a +ACI-no-mixing'' scenario. We further find that the C-ant is in transient steady state in the North Atlantic+ADs- that is, the C-ant concentration increases proportionally over time through the whole water column in a manner that is directly related to the time-dependent surface concentration.