Joint Seminar: Uptake of Anthropogenic Carbon by the Ocean

An independent estimate based on the transit time distribution approach

The oceanic uptake and inventory of anthropogenic carbon (Delta-C) remains uncertain, as evidenced by the range of estimates. We evaluate with GCM-generated data the accuracy of a new technique to infer these quantities. The "transit-time distribution" (TTD) technique allows a role for mixing in Delta-C transport, as constrained by tracer measurements, thereby relaxing the assumption of weak mixing made in a number of past studies. Applied to Indian Ocean WOCE CFC measurements Hall et al. [2004] used the TTD technique to estimate a lower Delta-C limit that was one-third less than several previous studies [Sabine et al, 1999; McNeil et al., 2003]. Waugh et al [2004] found similarly
reduced Delta-C levels in the North Atlantic using a form of the TTD technique. To test their methodology and corroborate (or contradict) their results we have used a version of the MIT OGCM to generate CFC and Delta-C fields in a hierarchy of simulations with progressively more realistic air-sea flux conditions and transport seasonality. We apply to the TTD technique to the synthetic CFC data and compare the inferred Delta-C to the "true" (directly-simulated) Delta-C. The added degree of realism in each simulation allows us to assess separately the key components of the TTD technique.




15:15–16:00 h


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Christian Rodehacke, IfM - ZMAW


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