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| Titel |
Estimation of NOx emissions from NO2 hotspots in polluted background using satellite observations |
| VerfasserIn |
Fei Liu, Steffen Beirle, Qiang Zhang, Thomas Wagner |
| 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 |
250105849
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| Publikation (Nr.) |
 EGU/EGU2015-5437.pdf |
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| Zusammenfassung |
| Satellite observations have been widely used to study NOx emissions from power plants and
cities, which are major NOx sources with large impacts on human health and climate. The
quantification of NOx emissions from measured column densities of NO2 requires
information on the NOx lifetime, which is typically gained from atmospheric chemistry
models. But some recent studies determined the NOx lifetime from the satellite observations
as well by analyzing the downwind plume evolution; however, this approach was so far only
applied for strong isolated “point sources” located in clean background, like Riyadh in Saudi
Arabia.
Here we present a modified method for the quantification of NOx emissions and
corresponding atmospheric lifetimes based on OMI observations of NO2, together with
ECMWF wind fields, but without further model input, for hot spots located in polluted
background. We use the observed NO2 patterns under calm wind conditions as proxy for the
spatial patterns of NOx emissions; by this approach, even complex source distributions can
be treated realistically. From the change of the spatial patterns of NO2 at larger wind speeds
(separately for different wind directions), the effective atmospheric lifetime is fitted.
Emissions are derived from integrated NO2 columns above background by division by the
corresponding lifetime.
NOx lifetimes and emissions are estimated for 19 power plants and 50 cities across China
and the US. The derived lifetimes are 3.3 ± 1.2 hours on average with extreme values of 0.9
to 7.7 hours. The resulting very short lifetimes for mountainous sites have been found to be
uncertain due to the potentially inaccurate ECMWF wind data in mountainous
regions. The derived NOx emissions show overall good agreement with bottom-up
inventories. |
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