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| Titel |
Chemical pathway analysis of the Martian atmosphere: The formation and destruction of ozone |
| VerfasserIn |
Joachim Stock, Christopher Boxe, Ralph Lehmann, Lee Grenfell, Beate Patzer, Heike Rauer, Yuk Yung |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092010
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| Publikation (Nr.) |
 EGU/EGU2014-6332.pdf |
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| Zusammenfassung |
| Ozone is a species of major importance in the Martian atmosphere e.g. since it is involved in
the stabilization of Mars’ major atmospheric constituent carbon dioxide. Below
approximately 40 km altitude, ozone acts as an atomic oxygen source which is produced
by photolysis and oxidizes carbon monoxide via catalytic cycles involving odd
hydrogen (HOx=H+OH+HO2). Originating mainly from H2O photolysis, odd hydrogen
destroys ozone resulting in the observed anti-correlation between water vapor and
ozone. Compared with species from the HOx-family, ozone is relatively easy to
detect by e.g. UV spectroscopy or IR heterodyne spectroscopy. Similar to carbon
dioxide, the concentration of ozone can be critically influenced by chemical trace
species acting as catalysts in chemical pathways. The identification of such chemical
pathways in complex reaction networks and the quantification of their contribution
are in general challenging. Therefore, we use an automated computer algorithm
(PAP - Pathway Analysis Program), which is specifically designed to address such
problems.
In this work, we apply the PAP-algorithm to the results of the newly updated
JPL/Caltech photochemical column model of the Martian atmosphere in order to
investigate Mars’ atmospheric ozone photochemistry. The efficiencies of individual
ozone formation and destruction pathways are calculated for different atmospheric
heights, by applying the algorithm to each vertical layer of the column model in
turn.
The results of our investigations suggest that ozone is primarily produced by a
Chapman-like mechanism, whereby atomic oxygen is produced by carbon dioxide photolysis
instead of molecular oxygen photolysis. In the ozone layer at approximately 40 km altitude,
ozone formation is chiefly dominated by a chemical pathway where atomic oxygen is
supplied by vertical transport. Ozone consumption pathways involving ozone photolysis are
most efficient except for a layer around 40 km altitude where the reaction between ozone and
atomic hydrogen become more important. These findings are of particular importance to
understand the dominating processes in Martian chemistry also in view of more complex
modelling approaches. |
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