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| Titel |
High-accuracy continuous airborne measurements of greenhouse gases (CO2 and CH4) using the cavity ring-down spectroscopy (CRDS) technique |
| VerfasserIn |
H. Chen, J. Winderlich, C. Gerbig, A. Hoefer, C. W. Rella, E. R. Crosson, A. D. Pelt, J. Steinbach, O. Kolle, V. Beck, B. C. Daube, E. W. Gottlieb, V. Y. Chow, G. W. Santoni, S. C. Wofsy |
| 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 ; 3, no. 2 ; Nr. 3, no. 2 (2010-03-24), S.375-386 |
| Datensatznummer |
250000970
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| Publikation (Nr.) |
 copernicus.org/amt-3-375-2010.pdf |
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| Zusammenfassung |
| High-accuracy continuous measurements of greenhouse gases (CO2 and
CH4) during the BARCA (Balanço Atmosférico Regional de Carbono
na Amazônia) phase B campaign in Brazil in May 2009 were accomplished
using a newly available analyzer based on the cavity ring-down spectroscopy
(CRDS) technique. This analyzer was flown without a drying system or any
in-flight calibration gases. Water vapor corrections associated with
dilution and pressure-broadening effects for CO2 and CH4 were
derived from laboratory experiments employing measurements of water vapor by
the CRDS analyzer. Before the campaign, the stability of the analyzer was
assessed by laboratory tests under simulated flight conditions. During the
campaign, a comparison of CO2 measurements between the CRDS analyzer
and a nondispersive infrared (NDIR) analyzer on board the same aircraft
showed a mean difference of 0.22±0.09 ppm for all flights over the
Amazon rain forest. At the end of the campaign, CO2 concentrations of
the synthetic calibration gases used by the NDIR analyzer were determined by
the CRDS analyzer. After correcting for the isotope and the
pressure-broadening effects that resulted from changes of the composition of
synthetic vs. ambient air, and applying those concentrations as calibrated
values of the calibration gases to reprocess the CO2 measurements made
by the NDIR, the mean difference between the CRDS and the NDIR during BARCA
was reduced to 0.05±0.09 ppm, with the mean standard deviation of
0.23±0.05 ppm. The results clearly show that the CRDS is sufficiently
stable to be used in flight without drying the air or calibrating in flight
and the water corrections are fully adequate for high-accuracy continuous
airborne measurements of CO2 and CH4. |
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