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| Titel |
ACE-FTS observations of pyrogenic trace species in boreal biomass burning plumes during BORTAS |
| VerfasserIn |
K. A. Tereszchuk, G. González Abad, C. Clerbaux, J. Hadji-Lazaro, D. Hurtmans, P.-F. Coheur, P. F. Bernath |
| 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. 9 ; Nr. 13, no. 9 (2013-05-02), S.4529-4541 |
| Datensatznummer |
250018624
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| Publikation (Nr.) |
 copernicus.org/acp-13-4529-2013.pdf |
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| Zusammenfassung |
To further our understanding of the effects of biomass burning emissions on
atmospheric composition, the BORTAS campaign (BOReal forest fires on
Tropospheric oxidants over the Atlantic using Aircraft and Satellites)
was conducted on 12 July to 3 August 2011 during the
boreal forest fire season in Canada. The simultaneous aerial, ground and
satellite measurement campaign sought to record instances of boreal biomass
burning to measure the tropospheric volume mixing ratios (VMRs) of short- and
long-lived trace molecular species from biomass burning emissions. The goal
was to investigate the connection between the composition and the
distribution of these pyrogenic outflows and their resulting perturbation to
atmospheric chemistry, with particular focus on oxidant species to determine
the overall impact on the oxidizing capacity of the free troposphere.
Measurements of pyrogenic trace species in boreal biomass burning plumes were
made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer
(ACE-FTS) onboard the Canadian Space Agency (CSA) SCISAT-1
satellite during the BORTAS campaign. Even though biomass burning emissions
are typically confined to the boundary layer, outflows are often injected
into the upper troposphere by isolated convection and fire-related convective
processes, thus allowing space-borne instruments to measure these pyrogenic
outflows. An extensive set of 14 molecules – CH3OH,
C2H2, C2H6,
C3H6O, CO, HCN, HCOOH, HNO3, H2CO,
NO, NO2, OCS, O3, and PAN – have been analysed. Included in
this analysis is the calculation of age-dependent sets of enhancement ratios
for each of the species originating from fires in North America (Canada,
Alaska) and Siberia for a period of up to 7 days. Ratio values for the
shorter lived primary pyrogenic species decrease over time primarily due to
oxidation by the OH radical as the plume ages and values for longer lived
species such as HCN and C2H6 remain relatively unchanged.
Increasing negative values are observed for the oxidant species, including
O3, indicating a destruction process in the plume as it ages such
that concentrations of the oxidant species have dropped below their off-plume
values.
Results from previous campaigns have indicated that values for the molar
ratios of ΔO3 /ΔO obtained from the measurements of the
pyrogenic outflow from boreal fires are highly variable and range from
negative to positive, irrespective of plume age. This variability has been
attributed to pollution effects where the pyrogenic outflows have mixed with
either local urban NOx emissions or pyrogenic emissions from the
long-range transport of older plumes, thus affecting the production of
O3 within the plumes. The results from this study have identified
another potential cause of the variability in O3 concentrations
observed in the measurements of biomass burning emissions, where evidence of
stratosphere–troposphere exchange due to the pyroconvective updrafts from
fires has been identified. Perturbations caused by the lofted emissions in
these fire-aided convective processes may result in the intrusion of
stratospheric air masses into the free troposphere and subsequent mixing of
stratospheric O3 into the pyrogenic outflows causing fluctuations
in observed ΔO3/ΔCO molar ratios. |
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