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| Titel |
The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study |
| VerfasserIn |
J. E. Williams, M. P. Scheele, P. F. J. Velthoven, J.-P. Cammas, V. Thouret, C. Galy-Lacaux, A. Volz-Thomas |
| 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. 15 ; Nr. 9, no. 15 (2009-08-11), S.5729-5749 |
| Datensatznummer |
250007567
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| Publikation (Nr.) |
 copernicus.org/acp-9-5729-2009.pdf |
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| Zusammenfassung |
| We have performed simulations using a 3-D global chemistry-transport model to
investigate the influence that biogenic emissions from the African continent
exert on the composition of the troposphere in the tropical region. For this
purpose we have applied two recently developed biogenic emission inventories
provided for use in large-scale global models (Granier et al., 2005;
Lathière et al., 2006) whose seasonality and temporal distribution for
biogenic emissions of isoprene, other volatile organic compounds and NO is
markedly different. The use of the 12 year average values for biogenic
emissions provided by Lathière et al. (2006) results in an increase in the
amount of nitrogen sequestrated into longer lived reservoir compounds which
contributes to the reduction in the tropospheric ozone burden in the tropics.
The associated re-partitioning of nitrogen between PAN, HNO3 and
organic nitrates also results in a ~5% increase in the loss of
nitrogen by wet deposition. At a global scale there is a reduction in the
oxidizing capacity of the model atmosphere which increases the atmospheric
lifetimes of CH4 and CO by ~1.5% and ~4%,
respectively. Comparisons against a range of different measurements indicate
that applying the 12 year average of Lathière et al. (2006) improves the
performance of TM4_AMMA for 2006 in the tropics. By the use of
sensitivity studies we show that the release of NO from soils in Africa
accounts for between ~2–45% of tropospheric ozone in the African
troposphere, ~10% in the upper troposphere and between ~5–20%
of the tropical tropospheric ozone column over the tropical
Atlantic Ocean. The subsequent reduction in OH over the source regions
allows enhanced transport of CO out of the region. For biogenic volatile
organic C1 to C3 species released from Africa, the effects on tropical
tropospheric ozone are rather limited, although this source contributes to
the global burden of VOC by between ~2–4% and has a large influence
on the organic composition of the troposphere over the tropical Atlantic
Ocean. |
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