 |
| Titel |
Formation of secondary organic aerosol from isoprene oxidation over Europe |
| VerfasserIn |
M. Karl, K. Tsigaridis, E. Vignati, F. Dentener |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022760
|
|
|
|
|
|
| Zusammenfassung |
| The role of isoprene as a precursor to secondary organic aerosol (SOA) in the atmosphere
over Europe was studied using the two-way nested global chemistry transport model TM5
with a horizontal resolution of 1×1 degrees. We analysed results from three scenarios: 1)
reference scenario: similar to the study by Tsigaridis and Kanakidou (Atmos. Chem. Phys., 3,
1849–1869, 2003) but including SOA formed from isoprene oxidation (SOA-I), 2) best guess
scenario: considers several updates in parameterisations and uses the recent MEGAN
isoprene emission inventory, and 3) zero SOA-I scenario: SOA formation from isoprene
oxidation is ignored. The predicted tropospheric production of SOA-I over Europe using the
best guess scenario is 0.10 Tg yr-1. Total tropospheric SOA production in this scenario is
0.70 Tg yr-1, roughly 40% higher than in the zero SOA-I scenario. Summertime
measurements of particulate organic matter (POM) 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 POM, likely caused by missing wood burning in
the emission inventories. Uncertainties in the parameterisation of isoprene SOA
formation have been investigated based on our reference scenario. The sensitivity of
our model results to different European isoprene emissions inventories, different
representations of the isoprene SOA formation route, and assumptions regarding the
effectiveness of wet removal of isoprene oxidation products were 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. The amount
and the nature of the absorbing matter are shown to be another key uncertainty
when predicting SOA levels. Tropospheric isoprene SOA production over Europe in
summer more than doubles when, in addition to pre-existing carbonaceous aerosols,
condensation of semi volatile vapours on ammonium and sulphate aerosols is considered. |
|
|
|
|
|
|