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| Titel |
Understanding why the volume of suboxic waters does not increase over centuries of global warming in an Earth System Model |
| VerfasserIn |
A. Gnanadesikan, J. P. Dunne, J. John |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 3 ; Nr. 9, no. 3 (2012-03-28), S.1159-1172 |
| Datensatznummer |
250006851
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| Publikation (Nr.) |
 copernicus.org/bg-9-1159-2012.pdf |
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| Zusammenfassung |
| Global warming is expected to reduce oxygen solubility and vertical exchange
in the ocean, changes which would be expected to result in an increase in
the volume of hypoxic waters. A simulation made with a full Earth System
model with dynamical atmosphere, ocean, sea ice and biogeochemical cycling
(the Geophysical Fluid Dynamics Laboratory's Earth System Model 2.1)
shows that this holds true if the condition for hypoxia is set relatively
high. However, the volume of the most hypoxic (i.e., suboxic) waters does not increase under
global warming, as these waters actually become more oxygenated. We show
that the rise in dissolved oxygen in the tropical Pacific is associated with a drop in ventilation time. A
term-by-term analysis within the least oxygenated waters shows an increased
supply of dissolved oxygen due to lateral diffusion compensating an increase in
remineralization within these highly hypoxic waters. This lateral diffusive
flux is the result of an increase of ventilation along the Chilean coast, as
a drying of the region under global warming opens up a region of wintertime
convection in our model. The results highlight the potential sensitivity of
suboxic waters to changes in subtropical ventilation as well as the importance
of constraining lateral eddy transport of dissolved oxygen in such waters. |
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