 |
| Titel |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
| VerfasserIn |
M. Hobe, J.-U. Grooß, R. Müller, S. Hrechanyy, U. Winkler, F. Stroh |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 5, no. 3 ; Nr. 5, no. 3 (2005-03-02), S.693-702 |
| Datensatznummer |
250002501
|
| Publikation (Nr.) |
 copernicus.org/acp-5-693-2005.pdf |
|
|
|
|
|
| Zusammenfassung |
| In-situ measurements of ClO and its dimer carried out during the SOLVE
II/VINTERSOL-EUPLEX and ENVISAT Validation campaigns in the Arctic winter
2003 suggest that the thermal equilibrium between the dimer formation and
dissociation is shifted significantly towards the monomer compared to the
current JPL 2002 recommendation. Detailed analysis of observations made in
thermal equilibrium allowed to re-evaluate the magnitude and temperature
dependence of the equilibrium constant. A fit of the JPL format for
equilibrium constants yields KEQ=3.61x10-27exp(8167/T), but
to reconcile the observations made at low temperatures with the existing
laboratory studies at room temperature, a modified equation,
KEQ=5.47x10-25(T/300)-2.29exp(6969/T), is required. This format
can be rationalised by a strong temperature dependence of the reaction
enthalpy possibly induced by Cl2O2 isomerism effects. At
stratospheric temperatures, both equations are practically equivalent. Using
the equilibrium constant reported here rather than the JPL 2002
recommendation in atmospheric models does not have a large impact on
simulated ozone loss. Solely at large zenith angles after sunrise, a small
decrease of the ozone loss rate due to the ClO dimer cycle and an increase
due to the ClO-BrO cycle (attributed to the enhanced equilibrium ClO
concentrations) is observed, the net effect being a slightly stronger ozone
loss rate. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|