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| Titel |
A mechanistic account of increasing seasonal variations in the rate of ocean uptake of anthropogenic carbon |
| VerfasserIn |
T. Gorgues, O. Aumont, K. B. Rodgers |
| 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 ; 7, no. 8 ; Nr. 7, no. 8 (2010-08-31), S.2581-2589 |
| Datensatznummer |
250004941
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| Publikation (Nr.) |
 copernicus.org/bg-7-2581-2010.pdf |
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| Zusammenfassung |
| A three-dimensional circulation model that includes a representation of
anthropogenic carbon as a passive tracer is forced with climatological
buoyancy and momentum fluxes. This simulation is then used to compute
offline the anthropogenic ΔpCO2 (defined as the difference
between the atmospheric CO2 and its seawater partial pressure) trends
over three decades between the years 1970 and 2000. It is shown that the
mean increasing trends in ΔpCO2 reflects an increase of the
seasonal amplitude of ΔpCO2. In particular, the ocean uptake of
anthropogenic CO2 is decreasing (negative trends in ΔpCO2)
in boreal (austral) summer in the Northern (Southern) Hemisphere in the subtropical gyres
between 20° N (S) and 40° N (S). In our simulation, the increased amplitude of
the seasonal trends of the ΔpCO2 is mainly explained by the
seasonal sea surface temperature (SST) acting on the anthropogenic increase
of the dissolved inorganic carbon (DIC). It is also shown that the
seasonality of the anthropogenic DIC has very little effect on the decadal
trends. Finally, an observing system for pCO2 that is biased towards
summer measurements may be underestimating uptake of anthropogenic CO2
by about 0.6 PgC yr−1 globally over the period of the WOCE survey in
the mid-1990s according to our simulations. This bias associated with summer
measurements should be expected to grow larger in time and underscores the
need for surface CO2 measurements that resolve the seasonal cycle
throughout much of the extratropical oceans. |
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