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| Titel |
On the origin of tropospheric O3 over the Indian Ocean during the winter monsoon: African biomass burning vs. stratosphere-troposphere exchange |
| VerfasserIn |
A. T. J. Laat |
| 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 ; 2, no. 5 ; Nr. 2, no. 5 (2002-11-13), S.325-341 |
| Datensatznummer |
250000654
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| Publikation (Nr.) |
 copernicus.org/acp-2-325-2002.pdf |
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| Zusammenfassung |
| This study investigates the origin of a commonly observed feature in the
O3 profiles: mid tropospheric O3
maxima (300--500 hPa) over the tropical Indian Ocean. A
comparison and analysis of model simulations, using a 3-D global climate-chemistry
model, and measured O3
profiles from the INDOEX campaign is presented. European
Centre for Medium-Range Weather Forecast (ECMWF) meteorological analyses have
been assimilated into the 3-D model to represent actual meteorology. The model
realistically simulates the observed mid-tropospheric O3
maxima. The analysis of the
model simulations shows that the major source of the mid-tropospheric
O3 maxima is
advection of polluted air masses from continental biomass burning areas over Africa,
with generally only a small contribution of stratospheric O3. Previous studies hinted at
stratosphere-troposphere exchange (STE) along the subtropical jet (STJ) as the
primary source of the mid-tropospheric O3
maxima over the Indian Ocean. Analysis of the model simulations shows that the mechanism causing the
mid-tropospheric transport of African biomass burning pollution and stratospheric air
masses are frontal zones or waves passing along the subtropical jets, causing
advection of tropical air masses in the prefrontal (equatorward) zone. Furthermore, the
frontal zones or waves also cause STE at the poleward side of the STJ. The model
simulations also indicate that the contribution of STE in general is minor compared to
advection and in situ tropospheric production of O3
for the mid-tropospheric O3
budget over the Indian Ocean region. |
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