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| Titel |
Airborne observations of formic acid using a chemical ionization mass spectrometer |
| VerfasserIn |
M. Breton, M. R. Mcgillen, J. B. A. Muller, A. Bacak, D. E. Shallcross, P. Xiao, L. G. Huey, D. Tanner, H. Coe, 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 ; 5, no. 12 ; Nr. 5, no. 12 (2012-12-07), S.3029-3039 |
| Datensatznummer |
250003209
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| Publikation (Nr.) |
 copernicus.org/amt-5-3029-2012.pdf |
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| Zusammenfassung |
The first airborne measurements of formic acid mixing ratios over the United
Kingdom were measured on the FAAM BAe-146 research aircraft on 16 March 2010
with a chemical ionization mass spectrometer using I−
reagent ions. The I− ionization scheme was able to measure formic acid
mixing ratios at 1 Hz in the boundary layer.
In-flight standard addition calibrations from a formic acid source were used
to determine the instrument sensitivity of 35 ± 6 ion counts
pptv−1 s−1 and a limit of detection of 25 pptv. Routine
measurements were made through a scrubbed inlet to determine the
instrumental background. Three plumes of formic acid were observed over the
UK, originating from London, Humberside and Tyneside. The London plume had
the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv.
No significant correlations of formic acid with NOx and ozone
were found, but a positive correlation was observed between CO and HCOOH
within the two plumes where coincident data were recorded.
A trajectory model was employed to determine the sources of the plumes and
compare modelled mixing ratios with measured values. The model
underestimated formic acid concentrations by up to a factor of 2. This is
explained by missing sources in the model, which were considered to be both
primary emissions of formic acid of mainly anthropogenic origin and a lack
of precursor emissions, such as isoprene, from biogenic sources, whose
oxidation in situ would lead to formic acid formation. |
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