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SUMMARY:Atmospheric bromine: from tropics to polar regions - Dr. Xin Yang 
 ( Centre for Atmospheric Science)
DTSTART:20110509T131500Z
DTEND:20110509T141500Z
UID:TALK29339@talks.cam.ac.uk
CONTACT:Dr Alex Archibald
DESCRIPTION:The depletion of the stratospheric ozone due to reactive halog
 en species (RHS) is well known. Most of the RHS in the stratosphere come f
 rom the long-lived halocarbons (e.g. CFCs etc.). Very short-lived substanc
 es (VSLS)\,  uch as CHBr3\, etc.\, mainly from tropical oceans\, could rea
 ch stratosphere through vertical transport. However\, the inorganic produc
 ts from the degradation of the VSLS could also make contribution to the st
 ratospheric RHS. In the tropical marine boundary layer\, several pptv of B
 rO were observed near Cape Verde\, but not in Borneo. The possible reason 
 for this discrepancy and implication for the sea salt bromine source will 
 be discussed. In the polar boundary layer\, significant ozone depletion ev
 ents (ODEs) during spring have been observed in\nboth Antarctic and Arctic
 \, which is thought attributed to catalytic destruction by bromine radical
 s (Br and BrO)\, especially during bromine explosion events (BEs). However
 \, neither the exact source of the bromine nor the formation of ODEs is co
 mpletely understood. Here in this presentation\, I will introduce a novel 
 bromine source from sea salt produced over sea ice\, and show a detailed c
 omparison between model and observation. The bromine effect on polar surfa
 ce HOx and global mercury oxidation will also be presented in the talk.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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