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| Titel |
Characterization and mitigation of water vapor effects in the measurement of ozone by chemiluminescence with nitric oxide |
| VerfasserIn |
P. Boylan, D. Helmig, J.-H. Park |
| 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 ; 7, no. 5 ; Nr. 7, no. 5 (2014-05-13), S.1231-1244 |
| Datensatznummer |
250115754
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| Publikation (Nr.) |
 copernicus.org/amt-7-1231-2014.pdf |
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| Zusammenfassung |
| Laboratory experiments were conducted to investigate the effects of water
vapor on the reaction of nitric oxide with ozone in a gas-phase
chemiluminescence instrument used for fast response and high sensitivity
detection of atmospheric ozone. Water vapor was introduced into a constant
level ozone standard and both ozone and water vapor signals were recorded at
10 Hz. The presence of water vapor was found to reduce, i.e. quench, the
ozone signal. A dimensionless correction factor was determined to be
4.15 ± 0.14 × 10−3, which corresponds to a 4.15%
increase in the corrected ozone signal per 10 mmol mol−1 of co-sampled
water vapor. An ozone-inert water vapor permeable membrane (a Nafion dryer
with a counterflow of dry air from a compressed gas cylinder) was installed
in the sampling line and was shown to remove the bulk of the water vapor in
the sample air. At water vapor mole fractions above 25 mmol mol−1, the
Nafion dryer removed over 75% of the water vapor in the sample. This
reduced the required ozone signal correction from over 11% to less than
2.5%. The Nafion dryer was highly effective at reducing the fast
fluctuations of the water vapor signal (more than 97%) while leaving the
ozone signal unaffected, which is a crucial improvement for minimizing the
quenching interference of water vapor fluxes and required density correction
in the determination of ozone fluxes by the eddy covariance technique. |
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