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| Titel |
Secondary organic aerosol from biogenic VOCs over West Africa during AMMA |
| VerfasserIn |
G. Capes, J. G. Murphy, C. E. Reeves, J. B. McQuaid, J. F. Hamilton, J. R. Hopkins, J. Crosier, P. I. Williams, H. Coe |
| 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. 12 ; Nr. 9, no. 12 (2009-06-15), S.3841-3850 |
| Datensatznummer |
250007421
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| Publikation (Nr.) |
 copernicus.org/acp-9-3841-2009.pdf |
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| Zusammenfassung |
| This paper presents measurements of organic aerosols above subtropical West
Africa during the wet season using data from the UK Facility for Airborne
Atmospheric Measurements (FAAM) aircraft. Measurements of biogenic volatile
organic compounds (BVOC) at low altitudes over these subtropical forests
were made during the African Monsoon Multidisciplinary Analysis (AMMA) field
experiment during July and August 2006 mainly above Benin, Nigeria and
Niger. Data from an Aerodyne Quadrupole Aerosol Mass Spectrometer show a
median organic aerosol loading of 1.07 μg m−3 over tropical West
Africa, which represents the first regionally averaged assessment of organic
aerosol mass (OM) in this region during the wet season. This is broadly in
agreement with global model predictions based on partitioning schemes,
although there are large uncertainties associated with such estimates. In
contrast our own calculations based on aerosol yields from isoprene and
monoterpenes during chamber studies under represent the OM measured in this
region on a comparable scale to the under representations of OM by
predictive models in the mid latitudes. As global models rely on similar
yield calculations in their global estimates, as our calculations this points
to further systematic differences between global model estimates and
measurements of SOA, most likely caused by use of incorrect BVOC emission
rates. The under predictions of OM by our calculations and those in the mid
latitudes employ yields extrapolated from chamber data obtained at higher
mass concentrations – more recent yield data for α-pinene obtained
at ambient concentrations in a flow through chamber
(Shilling et al., 2008) show considerably better
agreement with our data. |
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