A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations
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...
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00049132 2023-05-15T15:08:44+02:00 A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations von Hobe, M. Grooß, J.-U. Müller, R. Hrechanyy, S. Winkler, U. Stroh, F. 2005-03 electronic https://doi.org/10.5194/acp-5-693-2005 https://noa.gwlb.de/receive/cop_mods_00049132 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048752/acp-5-693-2005.pdf https://acp.copernicus.org/articles/5/693/2005/acp-5-693-2005.pdf eng eng Copernicus Publications Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-5-693-2005 https://noa.gwlb.de/receive/cop_mods_00049132 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048752/acp-5-693-2005.pdf https://acp.copernicus.org/articles/5/693/2005/acp-5-693-2005.pdf https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2005 ftnonlinearchiv https://doi.org/10.5194/acp-5-693-2005 2022-02-08T22:37:38Z 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. Article in Journal/Newspaper Arctic Niedersächsisches Online-Archiv NOA Arctic Atmospheric Chemistry and Physics 5 3 693 702 |
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article Verlagsveröffentlichung von Hobe, M. Grooß, J.-U. Müller, R. Hrechanyy, S. Winkler, U. Stroh, F. A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
topic_facet |
article Verlagsveröffentlichung |
description |
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. |
format |
Article in Journal/Newspaper |
author |
von Hobe, M. Grooß, J.-U. Müller, R. Hrechanyy, S. Winkler, U. Stroh, F. |
author_facet |
von Hobe, M. Grooß, J.-U. Müller, R. Hrechanyy, S. Winkler, U. Stroh, F. |
author_sort |
von Hobe, M. |
title |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
title_short |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
title_full |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
title_fullStr |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
title_full_unstemmed |
A re-evaluation of the ClO/Cl2O2 equilibrium constant based on stratospheric in-situ observations |
title_sort |
re-evaluation of the clo/cl2o2 equilibrium constant based on stratospheric in-situ observations |
publisher |
Copernicus Publications |
publishDate |
2005 |
url |
https://doi.org/10.5194/acp-5-693-2005 https://noa.gwlb.de/receive/cop_mods_00049132 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048752/acp-5-693-2005.pdf https://acp.copernicus.org/articles/5/693/2005/acp-5-693-2005.pdf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-5-693-2005 https://noa.gwlb.de/receive/cop_mods_00049132 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00048752/acp-5-693-2005.pdf https://acp.copernicus.org/articles/5/693/2005/acp-5-693-2005.pdf |
op_rights |
https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/acp-5-693-2005 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
5 |
container_issue |
3 |
container_start_page |
693 |
op_container_end_page |
702 |
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1766340045083508736 |