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| Titel |
Evaluation of a regional air quality model using satellite column NO2: treatment of observation errors and model boundary conditions and emissions |
| VerfasserIn |
R. J. Pope, M. P. Chipperfield, N. H. Savage, C. Ordóñez, L. S. Neal, L. A. Lee, S. S. Dhomse, N. A. D. Richards, T. D. Keslake |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 10 ; Nr. 15, no. 10 (2015-05-21), S.5611-5626 |
| Datensatznummer |
250119745
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| Publikation (Nr.) |
 copernicus.org/acp-15-5611-2015.pdf |
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| Zusammenfassung |
| We compare tropospheric column NO2 between the UK Met Office operational
Air Quality in the Unified Model (AQUM) and satellite observations from the
Ozone Monitoring Instrument (OMI) for 2006. Column NO2 retrievals from
satellite instruments are prone to large uncertainty from random, systematic
and smoothing errors. We present an algorithm to reduce the random error of
time-averaged observations, once smoothing errors have been removed with
application of satellite averaging kernels to the model data. This reduces
the total error in seasonal mean columns by 10–70%, which allows critical
evaluation of the model. The standard AQUM configuration evaluated here uses
chemical lateral boundary conditions (LBCs) from the GEMS (Global and
regional Earth-system Monitoring using Satellite and in situ data)
reanalysis. In summer the standard AQUM overestimates column NO2 in
northern England and Scotland, but underestimates it over continental Europe.
In winter, the model overestimates column NO2 across the domain. We show
that missing heterogeneous hydrolysis of N2O5 in AQUM is a significant
sink of column NO2 and that the introduction of this process corrects some
of the winter biases. The sensitivity of AQUM summer column NO2 to
different chemical LBCs and NOx emissions data sets are investigated.
Using Monitoring Atmospheric Composition and Climate (MACC) LBCs increases
AQUM O3 concentrations compared with the default GEMS LBCs. This enhances
the NOx–O3 coupling leading to increased AQUM column NO2 in both
summer and winter degrading the comparisons with OMI. Sensitivity experiments
suggest that the cause of the remaining northern England and Scotland summer
column NO2 overestimation is the representation of point source (power
station) emissions in the model. |
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