The anthropogenic contribution to atmospheric black carbon concentrations in southern Africa: a WRF-Chem modeling study
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Date
2015Author
Kuik, F.
Beukes, J.P.
Van Zyl, P.G.
Josipovic, M.
Laakso, L.
Lauer, A.
Vakkari, V.
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South Africa has one of the largest industrialized
economies in Africa. Emissions of air pollutants are particularly
high in the Johannesburg-Pretoria metropolitan area, the
Mpumalanga Highveld and the Vaal Triangle, resulting in local
air pollution. This study presents and evaluates a setup
for conducting modeling experiments over southern Africa
with the Weather Research and Forecasting model including
chemistry and aerosols (WRF-Chem), and analyzes the contribution
of anthropogenic emissions to the total black carbon
(BC) concentrations from September to December 2010.
The modeled BC concentrations are compared with
measurements obtained at the Welgegund station situated
ca. 100 km southwest of Johannesburg. An evaluation of
WRF-Chem with observational data from ground-based
measurement stations, radiosondes, and satellites shows that
the meteorology is modeled mostly reasonably well, but precipitation
amounts are widely overestimated and the onset of
the wet season is modeled approximately 1 month too early
in 2010. Modeled daily mean BC concentrations show a temporal
correlation of 0.66 with measurements, but the total BC
concentration is underestimated in the model by up to 50 %.
Sensitivity studies with anthropogenic emissions of BC
and co-emitted species turned off show that anthropogenic
sources can contribute up to 100% to BC concentrations in
the industrialized and urban areas, and anthropogenic BC and
co-emitted species together can contribute up to 60% to PM1
levels. Particularly the co-emitted species contribute significantly
to the aerosol optical depth (AOD). Furthermore, in areas
of large-scale biomass-burning atmospheric heating rates
are increased through absorption by BC up to an altitude of
about 600 hPa
URI
http://hdl.handle.net/10394/16939https://doi.org/10.5194/acp-15-8809-2015
https://www.atmos-chem-phys.net/15/8809/2015/