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| Titel |
On which timescales do gas transfer velocities control North Atlantic CO2
flux variability? |
| VerfasserIn |
Matthew Couldrey, Kevin Oliver, Andrew Yool, Paul Halloran, Eric Achterberg |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122205
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| Publikation (Nr.) |
 EGU/EGU2016-1180.pdf |
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| Zusammenfassung |
| The North Atlantic is an important basin for the global ocean’s uptake of anthropogenic and
natural carbon dioxide (CO2), but the mechanisms controlling this carbon flux are not fully
understood. The air-sea flux of CO2, F, is the product of a gas transfer velocity, k, the air-sea
CO2concentration gradient, ΔpCO2, and the temperature and salinity-dependent solubility
coefficient, α. k is difficult to constrain, representing the dominant uncertainty in F on short
(instantaneous to interannual) timescales. Previous work shows that in the North Atlantic,
ΔpCO2and k both contribute significantly to interannual F variability, but that k is
unimportant for multidecadal variability. On some timescale between interannual and
multidecadal, gas transfer velocity variability and its associated uncertainty become
negligible. Here, we quantify this critical timescale for the first time. Using an ocean model,
we determine the importance of k, ΔpCO2and α on a range of timescales. On interannual
and shorter timescales, both ΔpCO2and k are important controls on F. In contrast,
pentadal to multidecadal North Atlantic flux variability is driven almost entirely
by ΔpCO2; k contributes less than 25%. Finally, we explore how accurately one
can estimate North Atlantic F without a knowledge of non-seasonal k variability,
finding it possible for interannual and longer timescales. These findings suggest that
continued efforts to better constrain gas transfer velocities are necessary to quantify
interannual variability in the North Atlantic carbon sink. However, uncertainty in k
variability is unlikely to limit the accuracy of estimates of longer term flux variability. |
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