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| Titel |
Combined simulation of carbon and water isotopes in a global ocean model |
| VerfasserIn |
Andre Paul, Annegret Krandick, Jake Gebbie, Olivier Marchal, Stephanie Dutkiewicz, Martin Losch, Takasumi Kurahashi-Nakamura, Thejna Tharammal |
| 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 |
250076901
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| Zusammenfassung |
| Carbon and water isotopes are included as passive tracers in the MIT general circulation
model (MITgcm). The implementation of the carbon isotopes is based on the existing
MITgcm carbon cycle component and involves the fractionation processes during
photosynthesis and air-sea gas exchange. Special care is given to the use of a real freshwater
flux boundary condition in conjunction with the nonlinear free surface of the ocean
model. The isotopic content of precipitation and water vapor is obtained from an
atmospheric GCM (the NCAR CAM3) and mapped onto the MITgcm grid system,
but the kinetic fractionation during evaporation is treated explicitly in the ocean
model.
In a number of simulations, we test the sensitivity of the carbon isotope distributions to
the formulation of fractionation during photosynthesis and compare the results to modern
observations of δ13C and Δ14C from GEOSECS, WOCE and CLIVAR. Similarly, we
compare the resulting distribution of oxygen isotopes to modern δ18O data from the NASA
GISS Global Seawater Oxygen-18 Database. The overall agreement is good, but there are
discrepancies in the carbon isotope composition of the surface water and the oxygen isotope
composition of the intermediate and deep waters.
The combined simulation of carbon and water isotopes in a global ocean model will
provide a framework for studying present and past states of ocean circulation such as
postulated from deep-sea sediment records. |
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