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| Titel |
Water mass analysis of effect of climate change on air-sea CO2 fluxes. The Southern Ocean. |
| VerfasserIn |
Roland Séférian, Daniele Iudicone, Laurent Bopp |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050888
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| Zusammenfassung |
| The impact of climate change on the air-sea CO2 exchange has been proven to be strongly
regional dependent, but the exact mechanisms are still poorly constrained. Here, we propose
to explicit the role of the ocean dynamics on the air-sea CO2 fluxes into a water mass
framework. As a case study, we choose the Southern Ocean because its circulation
redistributes water mass contents (heat, salt, dissolved carbon) from one basin to another thus
playing a major role in the climate system. In a water mass framework, we investigate how
increasing atmospheric CO2 and resulting climate change affect both air-sea CO2
fluxes and outcrop surface areas of water masses. Using a global model of marine
biogeochemistry embedded in a climate model, we perform two 140-year transient CMIP5
simulations, in which only atmospheric CO2 or both atmospheric CO2 and climate change
affect the ocean carbon cycle. We find that air-sea CO2 flux patterns are organized
along with density gradients at preindustrial state and display specific water mass
responses to atmospheric CO2 and climate change. Experiments reveal that these
sensitivities rely on the water mass intrinsic geochemical and climate sensitivities
(sensitivity to atmospheric CO2 and climate change, respectively). The water mass
intrinsic geochemical sensitivity depends on its buffering ability. Under changing
climate, stratification induces a southward shift of the density gradient resulting in
propagation of the lighter water masses. This change of the water mass patterns favor both
the CO2 uptake and the negative climate sensitivity of lighter water masses to the
detriment of the others resulting in a weakening of the Southern Ocean CO2 sink. |
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