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| Titel |
Smoke aerosol properties and ageing effects for northern temperate and boreal regions derived from AERONET source and age attribution |
| VerfasserIn |
T. Nikonovas, P. R. J. North, S. H. Doerr |
| 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 ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-17), S.7929-7943 |
| Datensatznummer |
250119910
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| Publikation (Nr.) |
 copernicus.org/acp-15-7929-2015.pdf |
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| Zusammenfassung |
| Particulate emissions from wildfires impact human health and have a large but
uncertain effect on climate. Modelling schemes depend on information about
emission factors, emitted particle microphysical and optical properties and
ageing effects, while satellite retrieval algorithms make use of
characteristic aerosol models to improve retrieval. Ground-based remote
sensing provides detailed aerosol characterisation, but does not contain
information on source. Here, a method is presented to estimate plume origin
land cover type and age for AERONET aerosol observations, employing
trajectory modelling using the HYSPLIT model, and satellite active fire and
aerosol optical thickness (AOT) observations from Moderate Resolution Imaging
Spectroradiometer (MODIS) and Along Track Scanning Radiometer
(AATSR). It is applied to AERONET stations located in or near northern
temperate and boreal forests for the period 2002–2013. The results from 629
fire attributions indicate significant differences in size distributions and
particle optical properties between different land cover types and plume age.
Smallest fine mode median radius (Rfv) are attributed to plumes
from cropland and/or natural vegetation mosaic (0.143 μm) and
grassland (0.157 μm) fires. North American evergreen needleleaf
forest emissions show a significantly smaller Rfv
(0.164 μm) than plumes from Eurasian mixed forests
(0.193 μm) and plumes attributed to the land cover types with
sparse tree cover – open shrubland (0.185 μm) and woody savannas
(0.184 μm). The differences in size distributions are related to
inferred variability in plume concentrations between the land cover types.
Significant differences are observed between day and night emissions, with
daytime emissions showing larger particle sizes. Smoke is predominantly
scattering for all of the classes with median single scattering albedo at
440 nm (SSA(440)) values close to 0.95 except the cropland emissions
which have an SSA(440) value of 0.9. Plumes aged for 4 days or older
have median Rfv larger by ~0.02 μm compared
to young smoke. Differences in size were consistent with a decrease in the
Ångström Exponent and increase in the asymmetry parameter. Only an
insignificant increase in SSA(λ) with ageing was found. |
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