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| Titel |
Evaluation of a cavity ring-down spectrometer for in situ observations of 13CO2 |
| VerfasserIn |
F. R. Vogel, L. Huang, D. Ernst, L. Giroux, S. Racki, D. E. J. Worthy |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 2 ; Nr. 6, no. 2 (2013-02-11), S.301-308 |
| Datensatznummer |
250017390
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| Publikation (Nr.) |
 copernicus.org/amt-6-301-2013.pdf |
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| Zusammenfassung |
| With the emergence of wide-spread application of new optical techniques to
monitor δ13C in atmospheric CO2 there is a growing need to
ensure well-calibrated measurements. We characterized one commonly available
instrument, a cavity ring-down spectrometer (CRDS) system used for continuous
in situ monitoring of atmospheric 13CO2. We found no dependency of
δ13C on the CO2 concentration in the range of 303–437 ppm.
We designed a calibration scheme according to the diagnosed instrumental
drifts and established a quality assurance protocol. We find that the
repeatability (1-σ) of measurements is 0.25‰ for 10 min
and 0.15‰ for 20 min integrated averages, respectively. Due to a
spectral overlap, our instrument displays a cross-sensitivity to CH4 of
0.42 ± 0.024‰ ppm−1. Our ongoing target measurements
yield standard deviations of δ13C from 0.22‰ to
0.28‰ for 10 min averages. We furthermore estimate the
reproducibility of our system for ambient air samples from weekly
measurements of a long-term target gas to be 0.18‰. We find only a
minuscule offset of 0.002 ± 0.025‰ between the CRDS and
Environment Canada's isotope ratio mass spectrometer (IRMS) results for four
target gases used over the course of one year. |
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