Toms Sherwen (a) *, Mathew Evans (a,b), Lucy Carpenter (a) Rainer Volkamer (c), Theodore Koenig (c), Barbara Dix (c), Carlos Ordonez (d), Alfonso Saiz-Lopez (e) Iodines Impact on Tropospheric Oxidants 1 a Wolfson Atmospheric Chemistry Laboratory (WACL), Department of Chemistry, University of York, UK b National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, UK c Cooperative Institute for Research in Environmental Sciences (CIRES), Department of Chemistry and Biochemistry, University of Colorado, CO, USA d Met Office, FitzRoy Road, Exeter, UK e Atmospheric Chemistry and Climate Group (AC2), Instituto de Qumica Fsica Rocasolano, CSIC, Madrid, Spain Halogens and O 3 Tropospheric O 3 Sources NO x / VOCs Sinks Depositional Chemical (H 2 O/ hv / HOx + halogens) Troposphere Halogens More labile source species Cl, Br, I History 2 Image: WHO, 2010 Aerosols Schematic HOI I2I2 I - CH 3 ICH 2 I 2 CH 2 IBrCH 2 IClIOII2OxI2Ox OIO IONO 2 HOI O 3 Deposition I2I2 IONO HI MicroalgaeMacroalgae I Dry Deposition Wet Deposition Modelled Iodine Partitioning 4 Emissions Organic 0.6 Tg Organic 0.6 Tg (CH 3 I, CH 2 IX) Inorganic 2.4 Tg Inorganic 2.4 Tg (HOI, I 2 ) % pptv Inorganic Observations 5 O 3 Decrease 6 O 3 loss by Route 7 OH Increase 8 OH O3O3 IO +HO 2 OH O3O3 IO +HO 2 O 3 for better or for worse - Daily change from maximum - Normalised to mean - Tropical Atlantic site - (Cape Verde) 9 Pollution Feedback Net O 3 loss ( photolysis driven) Interaction with NOx 10 Summary O 3, HO 2 concentrations with halogens OH with iodine 11 Toms Sherwen ( ) Scenario O 3 Burden ( Tg ) [OH] mean ( 1x10 5 molec. cm -3 ) v9-2 (no Bromine) v9-2 (inc. Bromine) % diff from no halogens Iodine % diff from no halogens % diff from v ( ) 1.8 ( ) ( net: OH with halogens ) Extra Slide 1 - Sondes 12 Extra Slide 2 - % O 3 zonal change 13 Extra Slide 3 - % O 3 spatial change 14 Extra Slide 4 - % O 3 column change 15 Extra Slide 5 - % O 3 EU spatial change 16 OH O3O3 IO +HO 2 OH O3O3 IO +HO 2 Extra Slide 6 - OH delta explanation