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| Titel |
Linking horizontal and vertical transports of biomass fire emissionsto the tropical Atlantic ozone paradox during the Northern Hemisphere winter season: climatology |
| VerfasserIn |
G. S. Jenkins, J.-H. Ryu |
| 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 ; 4, no. 2 ; Nr. 4, no. 2 (2004-03-22), S.449-469 |
| Datensatznummer |
250001603
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| Publikation (Nr.) |
 copernicus.org/acp-4-449-2004.pdf |
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| Zusammenfassung |
| During the Northern hemisphere winter season, biomass burning is widespread
in West Africa, yet the total tropospheric column ozone values (<30DU)
over much of the Tropical Atlantic Ocean (15°N-5°S) are relatively
low. At the same time, the tropospheric column ozone values in the Southern
Tropical Atlantic are higher than those in the Northern Hemisphere (ozone
paradox). We examine the causes for low tropospheric column ozone values by
considering the horizontal and vertical transport of biomass fire emissions
in West Africa during November through March, using observed data which
characterizes fires, aerosols, horizontal winds, precipitation, lightning
and outgoing longwave radiation. We have found that easterly winds prevail
in the lower troposphere but transition to westerly winds at pressure levels
lower than 500hPa. A persistent anticyclone over West Africa at 700hPa is
responsible for strong easterly winds, which causes a net outflow of
ozone/ozone precursors from biomass burning in West Africa across the
Atlantic Ocean towards South America. The lowest outgoing longwave radiation
(OLR) and highest precipitation rates are generally found over the central
Atlantic, some distance downstream of fires in West Africa making the
vertical transport of ozone and ozone precursors less likely and ozone
destruction more likely. However, lightning over land areas in Central
Africa and South America can lead to enhanced ozone levels in the upper
troposphere especially over the Southern tropical Atlantic during the
Northern Hemisphere winter season. |
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