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| Titel |
Segregation Effects on Chemical Reactions in Atmospheric Flows: A Comparison of Experimental and Modeling Results |
| VerfasserIn |
R. Dlugi, M. Berger, M. Zelger, A. Hofzumahaus, F. Rohrer, K. Lu, F. Holland, G. Kramm |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061580
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| Zusammenfassung |
| The chemical reaction cycle in the atmosphere can be influenced by the degree of
inhomogeneous mixing (segregation) as shown by results from several modeling and field
studies based on own measurements and data from literature. As a measure we compare the
intensity of segregation IS, the covariance of two reactants divided by the product of their
means. Further on parameters influencing IS (e.g. variances, correlation coefficients) and
their dependance on meteorological and chemical conditions are considered. These results are
compared with respect to the following reactions: Isoprene + OH, O3 + NO and the
photolysis of O3. In addition some estimates are given for the reaction HO2 + NO. The
intensity of segregation IS is mostly found to be negative in the range -0.3 < IS < 0,
which results in a reduced volume mean chemical removal rate compared to the
homogeneously mixed case. But the modeled and experimental results may differ by the
influence of the correlation coefficient between two reactants. For convective (i.e.,
unstable) conditions a tendency of increasing absolute values of -IS is found for
bimolecular reactions (e.g. OH + isoprene) with increasing buoyant production. This
effect is suppressed if - for example - significant chemical sinks for OH others than
isoprene exist. Up to now the only case with positive IS is evaluated for a strongly
varying photolysis frequency of O3 (as source of OH) for the reaction isoprene +
OH. |
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