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| Titel |
Analysis of a 39-year continuous atmospheric CO2 record from Baring Head, New Zealand |
| VerfasserIn |
B. B. Stephens, G. W. Brailsford, A. J. Gomez, K. Riedel, S. E. Mikaloff Fletcher, S. Nichol, M. Manning |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2013-04-23), S.2683-2697 |
| Datensatznummer |
250018213
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| Publikation (Nr.) |
 copernicus.org/bg-10-2683-2013.pdf |
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| Zusammenfassung |
| We present an analysis of a 39-year record of continuous atmospheric
CO2 observations made at Baring Head, New Zealand, filtered for steady
background CO2 mole fractions during southerly wind conditions. We
discuss relationships between variability in the filtered CO2 time
series and regional to global carbon cycling. Baring Head is well situated
to sample air that has been isolated from terrestrial influences over the
Southern Ocean, and experiences extended episodes of strong southerly winds
with low CO2 variability. The filtered Baring Head CO2 record
reveals an average seasonal cycle with amplitude of 0.95 ppm that is 13%
smaller and 3 weeks earlier in phase than that at the South Pole. Seasonal
variations in a given year are sensitive to the timing and magnitude of the
combined influences of Southern Ocean CO2 fluxes and terrestrial fluxes
from both hemispheres. The amplitude of the seasonal cycle varies throughout
the record, but we find no significant long-term seasonal changes with
respect to the South Pole. Interannual variations in CO2 growth rate in
the Baring Head record closely match the El Niño-Southern Oscillation,
reflecting the global reach of CO2 mole fraction anomalies associated
with this cycle. We use atmospheric transport model results to investigate
contributions to seasonal and annual-mean components of the observed
CO2 record. Long-term trends in mean gradients between Baring Head and
other stations are predominately due to increases in Northern Hemisphere
fossil-fuel burning and Southern Ocean CO2 uptake, for which there
remains a wide range of future estimates. We find that the postulated recent reduction in the efficiency of Southern Ocean
anthropogenic CO2 uptake, as a result of increased zonal winds, is too small to be detectable
as significant differences in atmospheric CO2 between mid to high latitude Southern
Hemisphere observing stations. |
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