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| Titel |
Natural variability in the surface ocean carbonate ion concentration |
| VerfasserIn |
N. S. Lovenduski, M. C. Long, K. Lindsay |
| 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 ; 12, no. 21 ; Nr. 12, no. 21 (2015-11-05), S.6321-6335 |
| Datensatznummer |
250118153
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| Publikation (Nr.) |
 copernicus.org/bg-12-6321-2015.pdf |
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| Zusammenfassung |
| We investigate variability in the surface ocean carbonate ion
concentration ([CO32−]) on the basis of a~long control
simulation with an Earth System Model. The simulation
is run with a prescribed, pre-industrial atmospheric CO2
concentration for 1000 years, permitting investigation of
natural [CO32−] variability on interannual to
multi-decadal timescales. We find high interannual variability in
surface [CO32−] in the tropical Pacific and at the
boundaries between the subtropical and subpolar gyres in the
Northern Hemisphere, and relatively low interannual variability in
the centers of the subtropical gyres and in the Southern Ocean.
Statistical analysis of modeled [CO32−] variance and
autocorrelation suggests that significant anthropogenic trends in
the saturation state of aragonite (Ωaragonite) are
already or nearly detectable at the sustained, open-ocean time series
sites, whereas several decades of observations are required to
detect anthropogenic trends in Ωaragonite in the
tropical Pacific, North Pacific, and North Atlantic. The detection
timescale for anthropogenic trends in pH is shorter than that for
Ωaragonite, due to smaller noise-to-signal ratios
and lower autocorrelation in pH. In the tropical Pacific, the
leading mode of surface [CO32−] variability is primarily
driven by variations in the vertical advection of dissolved
inorganic carbon (DIC) in association with El Niño–Southern
Oscillation. In the North Pacific, surface [CO32−]
variability is caused by circulation-driven variations in surface
DIC and strongly correlated with the Pacific Decadal Oscillation,
with peak spectral power at 20–30-year periods. North
Atlantic [CO32−] variability is also driven by variations
in surface DIC, and exhibits weak correlations with both the North
Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As
the scientific community seeks to detect the anthropogenic influence
on ocean carbonate chemistry, these results will aid the
interpretation of trends calculated from spatially and
temporally sparse observations. |
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