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| Titel |
Application of OMI tropospheric NO2 for air quality monitoring in Northern Europe: shipping and land-based case studies |
| VerfasserIn |
Iolanda Ialongo, Janne Hakkarainen, Jukka-Pekka Jalkanen, Lasse Johansson, Folkert Boersma, Nickolay Krotkov, Johanna Tamminen |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091376
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| Publikation (Nr.) |
 EGU/EGU2014-5668.pdf |
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| Zusammenfassung |
| Satellite-based data are very important for air quality applications in the Baltic Sea
area, because they provide information on air pollution over sea and there where
ground-based network and aircraft measurements are not available. Both the emissions
from urban sites over land and ships over sea, contribute to the tropospheric NO2
levels. The tropospheric NO2 monitoring at high latitudes using satellite data is
challenging because of the reduced light hours in winter and the snow-covered surface,
which make the retrieval complex, and because of the reduced signal due to low
Sun.
This work presents a detailed characterization of the tropospheric NO2 columns focused
on part of the Baltic Sea region using the Ozone Monitoring Instrument (OMI)
tropospheric NO2 standard product. Previous works have focused on larger seas and
lower latitudes. The results showed that, despite the regional area of interest, it is
possible to distinguish the signal from the main coastal cities and from the ships by
averaging the data over a seasonal time range. The summertime NO2 emission and
lifetime values (E = (1.0 ± 0.1)x1028 molec. and Ï = (3.0 ± 0.5) h, respectively)
in Helsinki were estimated from the decay of the signal with distance from the
city center. The method developed for megacities was successfully applied to a
smaller scale source, in both size and intensity (i.e., the city of Helsinki), which
is located at high latitudes (~ 60oN). The same methodology could be applied
to similar scale cities elsewhere, as far as they are relatively isolated from other
sources.
The transport by the wind plays an important role in the Baltic Sea area. The NO2 spatial
distribution is mainly determined by the contribution of strong westerly winds, which
dominate the wind patterns during summer. The comparison between the emissions from
model calculations and OMI NO2 tropospheric columns confirmed the applicability of
satellite data for ship emission monitoring. In particular, both the emission data and the OMI
observations showed similar year-to-year variability, with a drop in year 2009, corresponding
to the effect of the economical crisis. |
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