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| Titel |
Impact of NO2 tropospheric column observations on near-surface analyses of nitrogen oxides using an inverse model system |
| VerfasserIn |
Achim Strunk, Hendrik Elbern |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052400
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| Zusammenfassung |
| The EURopean Air pollution and Dispersion Inverse chemistry transport model
(EURAD-IM) is used to assess the impact of NO2 observations from the Ozone
Monitoring Instrument (OMI) on analyses of near-surface concentrations of nitrogen
oxides. To this end, OMI tropospheric NO2 columns were assimilated with the
four-dimensional variational (4d-var) data assimilation algorithm on a European
domain with a horizontal grid resolution of 15 km. During both a summer and
winter episode, initial values and emission rates have been jointly optimised for
two weeks. This assimilation period is pursued by a two weeks evaluation period
assessing persistent gain in simulation skill. Additionally, this setup is completed, for
reference, by a control run without any data assimilation. Simulation results are
continuously evaluated against representative ground-based observations from AirBase
(European Environment Agency). Moreover, the simulations are also compared to
NO2 tropospheric column observations from SCIAMACHY and GOME-2. The
optimisation procedure shows a good performance throughout the assimilation period for
both the summer and winter episode, resulting in correlations > 0.9 for the OMI
analyses. For the summer episode, a significant improvement of bias, rmse and
correlation values of surface level nitrogen dioxide estimates is encountered for
the assimilation period as well as for the subsequent evaluation period, while the
latter is successfully achieved through emission adjustments. In the winter case,
the OMI data is of less benefit for near-surface simulation skill due to a longer
lifetime of nitrogen oxides and thus a smaller impact on emission rate optimisation. |
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