Stock, Joachim W. and Blaszczak-Boxe, Christopher S. and Lehmann, Ralph and Grenfell, J. Lee and Patzer, A. Beate C. and Rauer, Heike and Yung, Yuk L. (2017) A detailed pathway analysis of the chemical reaction system generating the Martian vertical ozone profile. Icarus, 291 . pp. 192-202. ISSN 0019-1035. http://resolver.caltech.edu/CaltechAUTHORS:20161216-142604512
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Atmospheric chemical composition is crucial in determining a planet’s atmospheric structure, stability, and evolution. Attaining a quantitative understanding of the essential chemical mechanisms governing atmospheric composition is nontrivial due to complex interactions between chemical species. Trace species, for example, can participate in catalytic cycles – affecting the abundance of major and other trace gas species. Specifically, for Mars, such cycles dictate the abundance of its primary atmospheric constituent, carbon dioxide (CO_2), but also for one of its trace gases, ozone (O_3). The identification of chemical pathways/cycles by hand is extremely demanding; hence, the application of numerical methods, such as the Pathway Analysis Program (PAP), is crucial to analyze and quantitatively exemplify chemical reaction networks. Here, we carry out the first automated quantitative chemical pathway analysis of Mars’ atmosphere with respect to O_3. PAP was applied to JPL/Caltech’s 1-D updated photochemical Mars model’s output data. We determine all significant chemical pathways and their contribution to O_3 production and consumption (up to 80 km) in order to investigate the mechanisms causing the characteristic shape of the O_3 volume mixing ratio profile, i.e. a ground layer maximum and an ozone layer at ∼ 50 km. These pathways explain why an O_3 layer is present, why it is located at that particular altitude and what the different processes forming the near-surface and middle atmosphere O_3 maxima are. Furthermore, we show that the Martian atmosphere can be divided into two chemically distinct regions according to the O(^3P):O_3 ratio. In the lower region (below approximately 24 km altitude) O_3 is the most abundant O_ x ( = O_3 + O(^3P)) species. In the upper region (above approximately 24 km altitude), where the O_3 layer is located, O(^3P) is the most abundant O_x species. Earlier results concerning the formation of O_3 on Mars can now be explained with the help of chemical pathways leading to a better understanding of the vertical O_3 profile.
|Additional Information:||© 2016 Elsevier Inc. Received date: 7 December 2015; Revised date: 15 November 2016; Accepted date: 5 December 2016; Available online: 9 December 2016. This research has been partly supported by the Helmholtz Association through the research alliance “Planetary Evolution and Life”. This work was partially funded by grant AyA 2012-32237 awarded by the Spanish Ministerio de Economia y Competitividad. The authors would like to thank Run-Lie Shia and Dickens Saint-Hilaire for their contributions to the discussion.|
|Subject Keywords:||Atmospheres; chemistry; Atmospheres; composition; Mars; Mars; atmosphere; Photochemistry|
|Official Citation:||Joachim W. Stock, Christopher S. Blaszczak-Boxe, Ralph Lehmann, J. Lee Grenfell, A. Beate C. Patzer, Heike Rauer, Yuk L. Yung, A detailed pathway analysis of the chemical reaction system generating the Martian vertical ozone profile, Icarus, Volume 291, 15 July 2017, Pages 192-202, ISSN 0019-1035, http://doi.org/10.1016/j.icarus.2016.12.012. (http://www.sciencedirect.com/science/article/pii/S0019103516308181)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||16 Dec 2016 22:59|
|Last Modified:||19 Apr 2017 16:13|
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