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| Titel |
Characterisation of Central-African emissions based on MAX-DOAS measurements, satellite observations and model simulations over Bujumbura, Burundi. |
| VerfasserIn |
Clio Gielen, Francois Hendrick, Gaia Pinardi, Isabelle De Smedt, Trissevgeni Stavrakou, Huan Yu, Caroline Fayt, Christian Hermans, Maite Bauwens, Eugene Ndenzako, Pierre Nzohabonayo, Rachel Akimana, Sébastien Niyonzima, Jean-Francois Müller, Michel Van Roozendael |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250132350
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| Publikation (Nr.) |
 EGU/EGU2016-12850.pdf |
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| Zusammenfassung |
| Central Africa is known for its strong biogenic, pyrogenic, and to a lesser extent
anthropogenic emissions. Satellite observations of species like nitrogen dioxide (NO2)
and formaldehyde (HCHO), as well as inverse modelling results have shown that
there are large uncertainties associated with the emissions in this region. There
is thus a need for additional measurements, especially from the ground, in order
to better characterise the biomass-burning and biogenic products emitted in this
area.
We present MAX-DOAS measurements of NO2, HCHO, and aerosols performed in
Central Africa, in the city of Bujumbura, Burundi (3∘S, 29∘E, 850m). A MAX-DOAS
instrument has been operating at this location by BIRA-IASB since late 2013.
Aerosol-extinction and trace-gases 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 purpose, while in the case of NO2 and HCHO, the
MAX-DOAS vertical columns and profiles are used for validating 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 to MODIS fire
counts/radiative-power and GOME-2/OMI NO2 and HCHO satellite data, as well as
simulations from the NOAA backward trajectory model HYSPLIT. First results show that
HCHO seasonal variation around local noon 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). Regarding the
biogenic emissions, it is found that they play only a minor role in the observed HCHO
seasonality. These results are further assessed using the tropospheric 3D-CTM IMAGES. |
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