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SUMMARY:Chlorine activation and enhanced ozone depletion induced by wildfi
 re aerosol - Prof. Susan Solomon (Department of Earth\, Atmospheric\, and 
 Planetary Sciences\, Massachusetts Institute of Technology)
DTSTART:20230130T140000Z
DTEND:20230130T150000Z
UID:TALK196372@talks.cam.ac.uk
CONTACT:104065
DESCRIPTION:Remarkable perturbations in the stratospheric abundances of ch
 lorine species and ozone were observed over southern hemisphere mid-latitu
 des following the 2020 Australian wildfires. These changes in atmospheric 
 chemical composition suggest that wildfire aerosols affect stratospheric c
 hlorine and ozone depletion chemistry. Here we propose that wildfire aeros
 ol containing a mixture of oxidized organics and sulfate increases hydroch
 loric acid solubility and associated heterogeneous reaction rates\, activa
 ting reactive chlorine species and enhancing ozone loss rates at relativel
 y warm stratospheric temperatures. We test our hypothesis by comparing atm
 ospheric observations to model simulations that include the proposed mecha
 nism. Modelled changes in 2020 hydrochloric acid\, chlorine nitrate\, and 
 hypochlorous acid abundances are in good agreement with observations. Our 
 results indicate that wildfire aerosol chemistry\, while not accounting fo
 r the record duration of the 2020 Antarctic ozone hole\, does yield an inc
 rease in its area\, and a 3-5% depletion of southern mid-latitude total co
 lumn ozone. These findings increase concern that more frequent and intense
  wildfires could delay ozone recovery in a warming world.
LOCATION:zoom https://us02web.zoom.us/j/88479554336
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