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| Titel |
Ozone photochemistry in boreal biomass burning plumes |
| VerfasserIn |
M. Parrington, P. I. Palmer, A. C. Lewis, J. D. Lee, A. R. Rickard, P. Carlo, J. W. Taylor, J. R. Hopkins, S. Punjabi, D. E. Oram, G. Förster, E. Aruffo, S. J. Moller, S. J.-B. Bauguitte, J. D. Allan, H. Coe, R. J. Leigh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 15 ; Nr. 13, no. 15 (2013-08-01), S.7321-7341 |
| Datensatznummer |
250018794
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| Publikation (Nr.) |
 copernicus.org/acp-13-7321-2013.pdf |
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| Zusammenfassung |
| We present an analysis of ozone (O3) photochemistry observed by aircraft
measurements of boreal biomass burning plumes over eastern Canada in the
summer of 2011. Measurements of O3 and a number of key chemical species
associated with O3 photochemistry, including non-methane hydrocarbons
(NMHCs), nitrogen oxides (NOx) and total nitrogen containing
species (NOy), were made from the UK FAAM BAe-146 research
aircraft as part of the "quantifying the impact of BOReal forest fires on
Tropospheric oxidants over the Atlantic using Aircraft and Satellites"
(BORTAS) experiment between 12 July and 3 August 2011. The location and
timing of the aircraft measurements put BORTAS into a unique position to
sample biomass burning plumes from the same source region in Northwestern
Ontario with a range of ages. We found that O3 mixing ratios measured in
biomass burning plumes were indistinguishable from non-plume measurements,
but evaluating them in relationship to measurements of carbon monoxide (CO),
total alkyl nitrates (ΣAN) and the surrogate species NOz
(= NOy-NOx) revealed that the
potential for O3 production increased with plume age. We used NMHC ratios
to estimate photochemical ages of the observed biomass burning plumes between
0 and 10 days. The BORTAS measurements provided a wide dynamic range of
O3 production in the sampled biomass burning plumes with
ΔO3/ΔCO enhancement ratios increasing from
0.020 ± 0.008 ppbv ppbv−1 in plumes with photochemical ages less
than 2 days to 0.55 ± 0.29 ppbv ppbv−1 in plumes with
photochemical ages greater than 5 days. We found that the main contributing
factor to the variability in the ΔO3/ΔCO enhancement ratio
was ΔCO in plumes with photochemical ages less than 4 days, and that
was a transition to ΔO3 becoming the main contributing factor in
plumes with ages greater than 4 days. In comparing O3 mixing ratios with
components of the NOy budget, we observed that plumes with ages
between 2 and 4 days were characterised by high aerosol loading, relative
humidity greater than 40%, and low ozone production efficiency (OPE) of
7.7 ± 3.5 ppbv ppbv−1 relative to ΣAN and
1.6 ± 0.9 ppbv ppbv−1 relative to NOz. In plumes
with ages greater than 4 days, OPE increased to
472 ± 28 ppbv ppbv−1 relative to ΣAN and
155 ± 5 ppbv ppbv−1 relative to NOz. From the BORTAS
measurements we estimated that aged plumes with low aerosol loading were
close to being in photostationary steady state and O3 production in
younger plumes was inhibited by high aerosol loading and greater production
of ΣAN relative to O3. The BORTAS measurements of O3
photochemistry in boreal biomass burning plumes were found to be consistent
with previous summertime aircraft measurements made over the same region
during the Arctic Research of the Composition of the Troposphere
(ARCTAS-B) in 2008 and Atmospheric Boundary Layer Experiment (ABLE 3B)
in 1990. |
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