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| Titel |
Development of a cavity-enhanced absorption spectrometer for airborne measurements of CH4 and CO2 |
| VerfasserIn |
S. J. O'Shea, S. J.-B. Bauguitte, M. W. Gallagher, D. Lowry, C. J. Percival |
| 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. 5 ; Nr. 6, no. 5 (2013-05-02), S.1095-1109 |
| Datensatznummer |
250017882
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| Publikation (Nr.) |
 copernicus.org/amt-6-1095-2013.pdf |
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| Zusammenfassung |
| High-resolution CH4 and CO2 measurements were made on board the
FAAM BAe-146 UK (Facility for Airborne Atmospheric Measurements, British Aerospace-146) atmospheric research aircraft during a number of field
campaigns. The system was based on an infrared spectrometer using the cavity-enhanced
absorption spectroscopy technique. Correction functions to convert
the mole fractions retrieved from the spectroscopy to dry-air mole fractions
were derived using laboratory experiments and over a 3 month period showed
good stability. Long-term performance of the system was monitored using WMO
(World Meteorological Office) traceable calibration gases.
During the first year of operation (29 flights)
analysis of the system's in-flight calibrations suggest that its
measurements are accurate to 1.28 ppb (1σ repeatability at 1 Hz = 2.48 ppb)
for CH4 and 0.17 ppm (1σ repeatability at 1 Hz = 0.66 ppm)
for CO2. The system was found to be robust, no major motion
or altitude dependency could be detected in the measurements. An
inter-comparison between whole-air samples that were analysed post-flight
for CH4 and CO2 by cavity ring-down spectroscopy showed a mean
difference between the two techniques of −2.4 ppb (1σ = 2.3 ppb)
for CH4 and −0.22 ppm (1σ = 0.45 ppm) for CO2. In
September 2012, the system was used to sample biomass-burning plumes in
Brazil as part of the SAMBBA project (South AMerican Biomass Burning
Analysis). From these and simultaneous CO measurements, emission factors for
savannah fires were calculated. These were found to be 2.2 ± 0.2 g
(kg dry matter)−1 for CH4 and 1710 ± 171 g (kg dry
matter)−1 for CO2, which are in excellent agreement with
previous estimates in the literature. |
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