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SUMMARY:Ozone Secrets: Heterogeneous Chemistry in the Martian Atmosphere -
  Megan Brown\, The Open University and University of Cambridge
DTSTART:20231010T103000Z
DTEND:20231010T113000Z
UID:TALK205774@talks.cam.ac.uk
CONTACT:Vichawan (Print) Sakulsupich
DESCRIPTION:Mars is a cold and arid planet\, with an atmosphere less than 
 1% the surface pressure of Earth's. Yet it undergoes excessive seasonal ch
 anges\, from thick water ice clouds at high latitudes (aphelion – furthe
 st from the Sun) to global dust storms engulfing the entire planet (perihe
 lion – closest to the Sun). The chemical components in the atmosphere ar
 e similar to those known on Earth - CO2\, O2\, H2O – but in different qu
 antities and under extreme conditions on Mars. Hydroxyl radicals (OH and H
 O2) catalyse the reformation of CO2 and are responsible for carbon dioxide
  being the primary constituent of the atmosphere (95%). Ozone is a key tra
 ce gas for understanding these chemical reactions: it can be detected via 
 UV spectrometers aboard satellites and is sensitive to short-lived hydroxy
 l radicals. A discrepancy between observed ozone and ozone modelled throug
 h global climate models implies missing or inaccurate chemistry in our kno
 wledge of the martian atmosphere. One possible explanation for this ozone 
 deficit could be the heterogeneous uptake of hydroxyl radicals on water ic
 e particles. This causes a depletion in HOx and an increase in ozone. Usin
 g 1D and 3D atmospheric models\, we show evidence that heterogeneous react
 ions occur\, but have a greater impact on ozone under conditions when wate
 r vapour abundance is minimal. The effect of heterogeneous reactions is al
 so greater when water ice clouds persist for several sols\, as HOx remain 
 adsorbed and also when dissociation of adsorbed species occurs at the surf
 ace.\n\n----------------\n\nCAS UnionRoad is inviting you to a scheduled Z
 oom meeting.\n\nTopic: CAS seminar: Dr Megan Brown\nTime: Oct 10\, 2023 11
 :30 AM London\n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86862218141?
 pwd=MU50WndyeXZaOG1hTVc5ZzBkYTViZz09\n\nMeeting ID: 868 6221 8141\nPasscod
 e: 100422\n\n
LOCATION:Chemistry Dept\, Unilever Lecture Theatre and Zoom
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