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Titel |
Sensitivity analysis by the adjoint chemistry transport model DRAISfor an episode in the Berlin Ozone (BERLIOZ) experiment |
VerfasserIn |
K. Nester, H.-J. Panitz |
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 ; 6, no. 8 ; Nr. 6, no. 8 (2006-06-20), S.2091-2106 |
Datensatznummer |
250003921
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Publikation (Nr.) |
copernicus.org/acp-6-2091-2006.pdf |
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Zusammenfassung |
The Berlin Ozone Experiment (BERLIOZ) was carried out in
summer 1998. One of its purposes was the evaluation of Chemistry Transport
Models (CTM). CTM KAMM/DRAIS was one of the models considered. The data of
20 July were selected for evaluation. On that day, a pronounced ozone plume
developed downwind of the city. Evaluation showed that the KAMM/DRAIS model
is able to reproduce the meteorological and ozone data observed, except at
farther distances (60–80 km) downwind of the city. In that region, the DRAIS
model underestimates the measured ozone concentrations by 10–15 ppb,
approximately.
Therefore, this study was conducted to detect possible reasons for this
deviation. A comprehensive sensitivity analysis was carried out to determine
the most relevant model parameters. The adjoint DRAIS model was developed
for this purpose, because for this study the application of this model is
the most effective method of calculating the sensitivities. The least
squares of the measured and simulated ozone concentrations between 08:00 UTC and
16:00 UTC at two stations 30 km and 70 km downwind of the city centre were
chosen as distance function. The model parameters considered in this study
are the complete set of initial and boundary species concentrations,
emissions, and reaction rates, respectively. A sensitivity ranking showing
the relevance of the individual parameters in the set is determined for each
parameter set.
In order to find out which modification in the parameter sets most reduces
the cost function, simplified 4-D data assimilation was carried out. The
result of this data assimilation shows that modifications of the reaction
rates provide the best agreement between the measured and the simulated
ozone concentrations at both stations. However, the modified reaction rates
seem to be unrealistic for the whole simulation period. Therefore, the good
agreement should not be overestimated. The agreement is still acceptable
when the parameters in the other sets are modified together. The
investigation demonstrates that an analysis of this type can help to explain
inconsistencies between observations and simulations. But in the case
considered here the inconsistencies cannot be explained by an error in only
one parameter set. |
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