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| Titel |
Peroxy radical observations over West Africa during AMMA 2006: photochemical activity in the outflow of convective systems |
| VerfasserIn |
M. D. Andrés-Hernández, D. Kartal, L. Reichert, J. P. Burrows, J. Meyer Arnek, M. Lichtenstern, P. Stock, H. Schlager |
| 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. 11 ; Nr. 9, no. 11 (2009-06-05), S.3681-3695 |
| Datensatznummer |
250007359
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| Publikation (Nr.) |
 copernicus.org/acp-9-3681-2009.pdf |
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| Zusammenfassung |
Peroxy radical measurements made on board the DLR-Falcon research aircraft
over West Africa within the African Monsoon Multidisciplinary Analysis (AMMA)
campaign during the 2006 wet monsoon are presented in this study. The
analysis of data focuses on the photochemical activity of air masses sampled
during episodes of intense convection and biomass burning. Generally, the
total sum of peroxy radical mixing ratios, measured in the outflow of
convective clouds, are quite variable but occasionally are coupled with the
NO variations indicating the coexistence or simultaneous emission of NOx, with a potential radical precursor (i.e. formaldehyde, acetone or
peroxides), which has likely been transported to higher atmospheric
altitudes. Based on the measurements, significant O3 production rates
around 1 ppb/h in the MCS outflow are estimated by using a box model with
simplified chemistry. Peroxy radicals having mixing ratios around
20–25 pptv and with peak values of up to 60–70 pptv are measured within
biomass burning plumes, detected at the coast in Ghana. Calculations of
back-trajectory densities confirm the origin of these air masses being a
biomass burning region at southern latitudes and close to the Gulf of Guinea,
according to satellite pictures.
Measured peroxy radical concentrations agree reasonably with modelled
estimations taking into account simple local chemistry. Moreover, the
vertical profiles taken at the aircraft base in Ouagadougou, Burkina Faso,
indicate the common feature of having maximum concentrations between 2 and
4 km, in agreement with other literature values obtained under similar
conditions. |
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