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| Titel |
Spatial and temporal variability in the ratio of trace gases emitted from biomass burning |
| VerfasserIn |
T. T. Leeuwen, G. R. der Werf |
| 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 ; 11, no. 8 ; Nr. 11, no. 8 (2011-04-19), S.3611-3629 |
| Datensatznummer |
250009638
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| Publikation (Nr.) |
 copernicus.org/acp-11-3611-2011.pdf |
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| Zusammenfassung |
| Fires are a major source of trace gases and aerosols to the atmosphere. The
amount of biomass burned is becoming better known, most importantly due to
improved burned area datasets and a better representation of fuel
consumption. The spatial and temporal variability in the partitioning of
biomass burned into emitted trace gases and aerosols, however, has received
relatively little attention. To convert estimates of biomass burned to trace
gas and aerosol emissions, most studies have used emission ratios (or
emission factors (EFs)) based on the arithmetic mean of field measurement
outcomes, stratified by biome. However, EFs vary substantially in time and
space, even within a single biome. In addition, it is unknown whether the
available field measurement locations provide a representative sample for
the various biomes. Here we used the available body of EF literature in
combination with satellite-derived information on vegetation characteristics
and climatic conditions to better understand the spatio-temporal variability
in EFs. While focusing on CO, CH4, and CO2, our findings are
also applicable to other trace gases and aerosols. We explored relations
between EFs and different measurements of environmental variables that may
correlate with part of the variability in EFs (tree cover density,
vegetation greenness, temperature, precipitation, and the length of the dry
season). Although reasonable correlations were found for specific case
studies, correlations based on the full suite of available measurements were
lower and explained about 33%, 38%, 19%, and 34% of the
variability for respectively CO, CH4, CO2, and the Modified
Combustion Efficiency (MCE). This may be partly due to uncertainties in the
environmental variables, differences in measurement techniques for EFs,
assumptions on the ratio between flaming and smoldering combustion, and
incomplete information on the location and timing of EF measurements. We
derived new mean EFs, using the relative importance of each measurement
location with regard to fire emissions. These weighted averages were
relatively similar to the arithmetic mean. When using relations between the environmental variables and EFs to extrapolate to regional and global scales,
we found substantial differences, with for savannas 13% and 22% higher
CO and CH4 EFs than the arithmetic mean of the field studies, possibly
linked to an underrepresentation of woodland fires in EF measurement
locations. We argue that from a global modeling perspective, future
measurement campaigns could be more beneficial if measurements are made over
the full fire season, and if relations between ambient conditions and EFs
receive more attention. |
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