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| Titel |
Future climate impact on unfavorable meteorological conditions for the dispersion of air pollution in Brussels |
| VerfasserIn |
Rozemien De Troch, Julie Berckmans, Olivier Giot, Rafiq Hamdi, Piet Termonia |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106200
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| Publikation (Nr.) |
 EGU/EGU2015-5855.pdf |
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| Zusammenfassung |
| Belgium is one of the several countries in Europe where air quality levels of different
pollutants such as ozone, NOx, and Particulate Matter (PM) still exceed the prescribed
European norms multiple times a year (EEA, 2014). These pollution peaks have a great
impact on health and environment, in particular in large cities and urban environments. It is
well known that observed concentrations of air pollutants are strongly influenced by
emissions and meteorological conditions and therefore is sensitive to climate change. As the
effects of global climate change are increasingly felt in Belgium, policy makers
express growing interest in quantifying its effect on air pollution and the effort
required to meet the air quality targets in the next years and decennia (Lauwaet et al.,
2014).
In this study, two different stability indices are calculated for a 9-year period using
present (1991-1999) and future (2047-2055) climate data that has been obtained from a
dynamically downscaling of Global Climate Model data from the Arpège model using the
ALARO model at 4 km spatial resolution. The ALARO model is described in detail in
previous validation studies from De Troch et al. (2013) and Hamdi et al. (2013). The first
index gives a measure of the horizontal and vertical transport of nonreactive pollutants in
stable atmospheric conditions and has been proposed and tested by Termonia and Quinet
(2004). It gives a characteristic length scale l which is the ratio of the mean horizontal wind
speed and the Brunt-Väisälä frequency. In this way low values for l in the lower part of the
boundary layer during an extended time span of 12 hours, correspond to calm situations and a
stable atmosphere and thus indicate unfavorable conditions for the dispersion of air
pollution. This transport index is similar to an index used in an old Pasquill-type
scheme but is more convenient to use to detect the strongest pollution peaks. The well
known Pasquill classes are also calculated in order to provide a reference. Both
indices are calculated for the gridpoint of Uccle, located some 6 km from the city
centre of Brussels. As the transport index only applies for stable conditions which
mostly occur during the winter season, our analyses focuses on the DJF winter
months.
First results from a sensitivity analyses show higher frequencies in low transport lengths
(i.e. stable conditions) for future winter climate under the A1B scenario. This shift to more
stable and hence possibly favorable conditions for pollution peaks is also confirmed
by the frequency distributions of the Pasquill classes, showing higher frequencies
in the stable E and F classes for the future period. These results show that more
pollution peaks are to be expected by the middle of the 21st century in Brussels. |
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