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Communication incl. Poster: BibTeX citation key:  Minga
Minga, A., Thouret, V., Saunois, M., Delon, C., Mari, C. H., Serça, D., Sauvage, B., Mariscal, A., Leriche, M., Cros, B., Kounouhewa, B. & Akpo, A. 2009. Very high ozone concentrations from probable petrochemical pollution over Cotonou during the Dry Season (DJF). Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-11-23 20:00:23
Categories: Aerosol and Chemistry, Society-Environment-Climate interactions
Keywords: Health
Creators: Akpo, Cros, Delon, Kounouhewa, Leriche, Mari, Mariscal, Minga, Saunois, Sauvage, Serça, Thouret
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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In the frame of the AMMA program, 98 vertical profiles of ozone soundings have been performed from December 2004 to January 2007 above Cotonou (6°21’N, 2°23’E), in Benin. The ozone data were measured from the ECC sondes launched by balloons and using the Vaisala technique. Here we present the analysis of the seasonal and interannual variability of ozone during the dry season (DJF) in the Monsoon (0 -1.5 km) and Harmattan (1.5 - 4 km) layers. We also make a focus on the anomaly of the ozone observed on 20th, December 2005, where extremely high values of the ozone concentration were observed (up to 280 ppbv) in a layer located at the interface between the Monsoon and the Harmattan layers. Such high values have never been recorded before in the region. The maximum ozone mixing ratios over West Africa recorded by the MOZAIC aircraft between 1997 and 2004 was 120 ppb. This value has also been measured in Djougou (400 km north of Cotonou in the burning area) in December 2005. Values of ozone concentration greater than 200 ppb have been sampled at the surface stations or in the boundary layer in Beijing, Mexico city, and Houston. Such high concentrations are then realistic in regions combining a very large population and big sources of anthropogenic pollution including petrochemical industries (as for Houston). This combination is also valid for Lagos, Nigeria, situated 110 km east of Cotonou. Lagos is actually the largest city in West Africa and the 11th country for oil production with many pipelines in the city itself. To understand this ozone anomaly, we use the FLEXPART model to assess the origin of the ozone enhanced layer and the Master Mechanism box model to evaluate the chemical regime responsible of such high ozone concentrations and to test the hypothesis of a pipeline explosion releasing high concentrations of very reactive COVs.
Added by: roussot