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| Titel |
14C-based evaluation of ocean circulation models: why we need to care about correct preformed ages |
| VerfasserIn |
Wolfgang Koeve, Hannes Wagner, Andreas Oschlies |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080835
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| Zusammenfassung |
| Global ocean models are routinely used to study the effects on and feedbacks of
biogeochemical cycles induced by global warming, ocean acidification and de-oxygenation.
The underlying circulation fields of such models are often evaluated by comparing the models
14C-tracer distribution with those observed in the real ocean. Using the output from three
state of the art coupled carbon cycle ocean circulation models we study the impact of the
preformed 14C-age on this evaluation. Similar to other preformed properties, the preformed
14C-age is defined as the age a water parcel has when it leaves the surface ocean and is
subducted into the interior of the ocean. The preformed age component is highly variable
between models. On global average it is equivalent to 30-55 percent of the apparent age (the
age computed from the natural 14C content) in the deep ocean (below 1500m) and
even more important in shallower waters. Concerning the observational data, the
so-called ‘bomb-corrected’ 14C-distribution, we highlight the fact that this is a
computed property with clear conceptual limitations. We discuss the reliability of
current model evaluation procedures and propose improved evaluation schemes. |
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