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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2016-1104
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
10 Jan 2017
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This discussion paper is a preprint. A revision of the manuscript for further review has not been submitted.
Characterisation of Central-African aerosol and trace-gas emissions based on MAX-DOAS measurements and model simulations over Bujumbura, Burundi
Clio Gielen1, François Hendrick1, Gaia Pinardi1, Isabelle De Smedt1, Caroline Fayt1, Christian Hermans1, Trissevgeni Stavrakou1, Maite Bauwens1, Jean-Francois Müller1, Eugène Ndenzako2, Pierre Nzohabonayo2, Rachel Akimana2, Sebastien Niyonzima2, Michel Van Roozendael1, and Martine De Mazière1 1Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium
2Department of Physics, University of Burundi, Bujumbura, Burundi
Abstract. We present MAX-DOAS measurements of NO2, HCHO, and aerosols performed in Central Africa, in the city of Bujumbura, Burundi (3.38° S, 29.3° E). A MAX-DOAS instrument has been operated at this location by BIRA-IASB since late 2013. Aerosol-extinction and trace-gas vertical profiles are retrieved by applying the optimal-estimation-based profiling tool bePRO to the measured O4, NO2 and HCHO slant-column densities. The MAX-DOAS vertical columns and profiles are used for investigating the diurnal and seasonal cycles of NO2, HCHO, and aerosols. Regarding the aerosols, the retrieved AODs are compared to co-located AERONET sun-photometer measurements for verification purposes, while in the case of NO2 and HCHO, the MAX-DOAS vertical columns and profiles are compared to GOME-2 and OMI satellite observations.

To characterise the biomass-burning and biogenic emissions in the Bujumbura region, the trace gases and aerosol MAX-DOAS retrievals are used in combination with MODIS fire radiative-power values and the tropospheric 3D chemical transport model IMAGES, as well as simulations from the NOAA backward-trajectory model HYSPLIT. The first results show that the aerosol and HCHO seasonal variation is driven by the alternation of rain and dry periods, the latter being associated with intense biomass-burning agricultural activities and forest fires in the south/south-east and transport from this region to Bujumbura. In contrast, NO2 is seen to depend mainly on local emissions close to the city, due to the short lifetime of this species (typically 1–2 hours).


Citation: Gielen, C., Hendrick, F., Pinardi, G., De Smedt, I., Fayt, C., Hermans, C., Stavrakou, T., Bauwens, M., Müller, J.-F., Ndenzako, E., Nzohabonayo, P., Akimana, R., Niyonzima, S., Van Roozendael, M., and De Mazière, M.: Characterisation of Central-African aerosol and trace-gas emissions based on MAX-DOAS measurements and model simulations over Bujumbura, Burundi, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-1104, in review, 2017.
Clio Gielen et al.
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Clio Gielen et al.
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Short summary
In this paper we study the composition of the lower atmosphere above the Central-African capital city of Burundi (Bujumbura) by measuring the amount of aerosol dust particles and trace gases in the air. We find that the aerosol and trace gas seasonal and daily variation is driven by the alternation of rain periods and dry periods associated with intense biomass burning in the vicinity of Bujumbura, and the influence of human activities in the city center.
In this paper we study the composition of the lower atmosphere above the Central-African capital...
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