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| Titel |
Formation of secondary organic aerosol from isoprene oxidation over Europe |
| VerfasserIn |
M. Karl, K. Tsigaridis, E. Vignati, F. Dentener |
| 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 ; 9, no. 18 ; Nr. 9, no. 18 (2009-09-22), S.7003-7030 |
| Datensatznummer |
250007644
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| Publikation (Nr.) |
 copernicus.org/acp-9-7003-2009.pdf |
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| Zusammenfassung |
| The role of isoprene as a precursor to secondary organic aerosol (SOA)
over Europe is studied with the two-way nested global chemistry
transport model TM5. The inclusion of the formation of SOA from
isoprene oxidation in our model almost doubles the atmospheric burden
of SOA over Europe compared to SOA formation from terpenes and
aromatics. The reference simulation, which considers SOA formation
from isoprene, terpenes and aromatics, predicts a yearly European
production rate of 1.0 Tg SOA yr−1 and an annual averaged
atmospheric burden of about 50 Gg SOA over Europe. A fraction
of 35% of the SOA produced in the boundary layer over Europe is
transported to higher altitudes or to other world regions. Summertime
measurements of organic matter (OM) during the extensive
EMEP OC/EC campaign 2002/2003 are better reproduced when SOA formation
from isoprene is taken into account, reflecting also the strong
seasonality of isoprene and other biogenic volatile organic compounds
(BVOC) emissions from vegetation. However, during winter, our model
strongly underestimates OM, likely caused by missing wood burning in
the emission inventories. Uncertainties in the parameterisation of
isoprene SOA formation have been investigated. Maximum SOA production
is found for irreversible sticking (non-equilibrium partitioning) of
condensable vapours on particles, with tropospheric SOA production
over Europe increased by a factor of 4 in summer compared to the
reference case. Completely neglecting SOA formation from isoprene
results in the lowest estimate (0.51 Tg SOA yr−1). The
amount and the nature of the absorbing matter are shown to be another
key uncertainty when predicting SOA levels.
Consequently, smog chamber experiments on SOA formation should be performed
with different types of seed aerosols and without seed aerosols in order to
derive an improved treatment of the absorption of SOA in the models.
Consideration of a number of recent insights in isoprene SOA formation
mechanisms reduces the tropospheric production of isoprene derived SOA
over Europe from 0.4 Tg yr−1 in our reference simulation
to 0.1 Tg yr−1. |
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