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| Titel |
Mega fire emissions in Siberia: potential supply of bioavailable iron from forests to the ocean |
| VerfasserIn |
A. Ito |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 6 ; Nr. 8, no. 6 (2011-06-27), S.1679-1697 |
| Datensatznummer |
250005964
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| Publikation (Nr.) |
 copernicus.org/bg-8-1679-2011.pdf |
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| Zusammenfassung |
Significant amounts of carbon and nutrients are released to
the atmosphere due to large fires in forests. Characterization of the
spatial distribution and temporal variation of the intense fire emissions is
crucial for assessing the atmospheric loadings of trace gases and aerosols.
This paper discusses issues of the representation of forest fires in the
estimation of emissions and the application to an atmospheric chemistry
transport model (CTM). The potential contribution of forest fires to the
deposition of bioavailable iron (Fe) into the ocean is highlighted, with a
focus on mega fires in eastern Siberia.
Satellite products of burned area, active fire, and land cover are used to
estimate biomass burning emissions in conjunction with a biogeochemical
model. Satellite-derived plume height from MISR is used for the injection
height of boreal forest fire emissions. This methodology is applied to
quantify fire emission rates in each three-dimensional grid location in the
high latitude Northern Hemisphere (>30° N latitude) over a 5-yr
period from 2001 to 2005. There is large interannual variation in forest
burned area during 2001–2005 (13–49 × 103 km2 yr−1)
which results in a corresponding variation in the annual emissions of carbon
monoxide (CO) (14–81 Tg CO y−1). Satellite observations of CO column
from MOPITT are used to evaluate the model performance in simulating the
spatial distribution and temporal variation of the fire emissions. The model
results for CO enhancements due to eastern Siberian fires are in good
agreement with MOPITT observations. These validation results suggest that
the model using emission rates estimated in this work is able to describe
the interannual changes in CO due to intense forest fires.
Bioavailable iron is derived from atmospheric processing of relatively
insoluble iron from desert sources by anthropogenic pollutants (mainly
sulfuric acid formed from oxidation of SO2) and from direct emissions
of soluble iron from combustion sources. Emission scenarios for IPCC AR5
report (Intergovernmental Panel on Climate Change; Fifth Assessment Report)
suggest that anthropogenic SO2 emissions are suppressed in the future
to improve air quality. In future warmer and drier climate, severe fire
years such as 2003 may become more frequent in boreal regions. The fire
emission rates estimated in this study are applied to the aerosol chemistry
transport model to examine the relative importance of biomass burning
sources of soluble iron compared to those from dust sources. The model
reveals that extreme fire events contribute to a significant deposition of
soluble iron (20–40 %) to downwind regions over the western North Pacific
Ocean, compared to the dust sources with no atmospheric processing by acidic
species. These results suggest that the supply of nutrients from large
forest fires plays a role as a negative biosphere-climate feedback with
regards to the ocean fertilization. |
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