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SUMMARY:Reactive halogens in the polar boundary layer and volcanic plumes 
 - Implications for O3\, CH4 and mercury - Prof Roland von Glasow (UEA)
DTSTART:20140217T141500Z
DTEND:20140217T153000Z
UID:TALK49281@talks.cam.ac.uk
CONTACT:Dr Amanda Maycock
DESCRIPTION:Ozone Depletion Events (ODEs) have been known to occur in the 
 polar boundary layer for over 20 years. During such events\, ozone concent
 rations can fall from background amounts to below instrumental detection l
 imits within a few minutes and remain suppressed for on the order of hours
  to days. The chemical destruction of ozone is driven by halogens (especia
 lly bromine radicals) that have a source associated with the sea ice zone.
  Although our knowledge of ODEs has increased greatly since their discover
 y\, some of the key processes involved are not yet fully understood.\n\nDe
 spite our increasing understanding of the spatial variability of BrO and p
 ossible reaction pathways based on laboratory studies\, important question
 s remain regarding the most efficient sources of and mechanisms for Arctic
  halogen activation.  Recent findings indicate that atmospherically proces
 sed snow is likely a major source of Arctic bromine release\, which impact
 s the distribution and occurrence of ozone depletion events and BrO.  The 
 implications of snowpack photochemical bromine production on tropospheric 
 reactive bromine concentrations are explored using the one-dimensional hal
 ogen model MISTRA-Snow (Thomas et al.\, 2011\, 2012). Further ongoing and 
 planned work will be presented.\n\nAnother part of the atmosphere in which
  halogen chemistry has been found to be of importance in the troposphere i
 s a completely different environment – volcanic plumes. I will present r
 esults from recent measurements at the crater rim of Mt Etna as well as nu
 merical simulations from a 1D model and a regional 3D model. These models 
 are used to improve our understanding of the chemical and physical process
 es within volcanic plumes and to be able to assess the importance of this 
 chemistry for the chemistry of the troposphere.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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