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| Titel |
New emission factors for Australian vegetation fires measured using open-path Fourier transform infrared spectroscopy – Part 2: Australian tropical savanna fires |
| VerfasserIn |
T. E. L. Smith, C. Paton-Walsh, C. P. Meyer, G. D. Cook, S. W. Maier, J. Russell-Smith, M. J. Wooster, C. P. Yates |
| 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 ; 14, no. 20 ; Nr. 14, no. 20 (2014-10-29), S.11335-11352 |
| Datensatznummer |
250119124
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| Publikation (Nr.) |
 copernicus.org/acp-14-11335-2014.pdf |
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| Zusammenfassung |
Savanna fires contribute approximately 40–50% of total global annual
biomass burning carbon emissions. Recent comparisons of emission factors
from different savanna regions have highlighted the need for a regional
approach to emission factor development, and better assessment of the
drivers of the temporal and spatial variation in emission factors. This
paper describes the results of open-path Fourier transform infrared
(OP-FTIR) spectroscopic field measurements at 21 fires occurring in
the tropical savannas of the Northern~Territory, Australia, within different
vegetation assemblages and at different stages of the dry season. Spectra of
infrared light passing through a long (22–70 m) open-path through
ground-level smoke released from these fires were collected using an
infrared lamp and a field-portable FTIR system. The IR spectra were used to
retrieve the mole fractions of 14 different gases present within the
smoke, and these measurements used to calculate the emission ratios and
emission factors of the various gases emitted by the burning. Only a handful
of previous emission factor measures are available specifically for the
tropical savannas of Australia and here we present the first reported
emission factors for methanol, acetic acid, and formic acid for this biome.
Given the relatively large sample size, it was possible to study the
potential causes of the within-biome variation of the derived emission
factors. We find that the emission factors vary substantially between
different savanna vegetation assemblages; with a majority of this variation
being mirrored by variations in the modified combustion efficiency (MCE) of
different vegetation classes. We conclude that a significant majority of the
variation in the emission factor for trace gases can be explained by MCE,
irrespective of vegetation class, as illustrated by variations in the
calculated methane emission factor for different vegetation classes using
data sub-set by different combustion efficiencies. Therefore, the
selection of emission factors for emissions modelling purposes need not
necessarily require detailed fuel type information, if data on MCE (e.g.
from future spaceborne total column measurements) or a correlated variable
were available.
From measurements at 21 fires, we recommend the following emission
factors for Australian tropical savanna fires (in grams of gas emitted per
kilogram of dry fuel burned), which are our mean measured values: 1674 ± 56 g kg−1
of carbon dioxide; 87 ± 33 g kg−1 of
carbon monoxide; 2.1 ± 1.2 g kg−1 of methane; 0.11 ± 0.04 g kg−1
of acetylene; 0.49 ± 0.22 g kg−1 of ethylene; 0.08 ± 0.05 g kg−1
of ethane; 1.57 ± 0.44 g kg−1 of
formaldehyde; 1.06 ± 0.87 g kg−1 of methanol; 1.54 ± 0.64 g kg−1
of acetic acid; 0.16 ± 0.07 g kg−1 of formic acid;
0.53 ± 0.31 g kg−1 of hydrogen cyanide; and 0.70 ± 0.36 g kg−1
of ammonia. In a companion paper, similar techniques are used to
characterise the emissions from Australian temperate forest fires. |
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