1. Arctic Atmospheric Chemistry: the Polar Sunrise Experiments (PSE) Jan W. Bottenheim 1, Paul B. Shepson 2, Jose D. Fuentes 3, Leonard A. Barrie 4 1 Meteorological Service of Canada, Toronto, ON, Canada 2 Purdue University, West Lafayette, IN, USA 3 University of Virginia, Charlottesville, VA, USA 4 WMO, Geneva, Switzerland

2. Chronology of PSEs: 1988: first PSE 1992, 2000: major campaigns Yearly small, dedicated campaigns

3. Relationship between ozone and bromine From: Barrie et al., 1988

4. Br +O 3 ->BrO +O 2 BrO +BrO->2 Br +O 2 BrO + BrO limiting BrO +HO 2 ->HOBr HOBr + Br - ->2 Br

5. From: Foster et al., 2001 From: Hoenninger and Platt, 2002

7. From: Richter et al., 1998 GOME satellite data

8. Frequency of depletion episodes is increasing (0.7 % y -1 ), evidence of climate change? Most episodes occur where surface temperature is < -20 0 C Frost flower growth is efficient over new sea-ice, at a rate inversely proportional to temperature

9. The HCHO lifetime changes from ~3 months in the dark, to 0.5 days in sunlight From: Sumner and Shepson, 1999

10. Radical Source HCHO+ h H HO 2 HCHO+ h H HO 2 HO 2 +BrO  HOBr+O 2 HOBr( aq ) + Br - + H +  Br 2 ( aq )  Br 2 ( g ) + h  2 Br Bromine Radical Sink Br+O 3  BrO +O 2 Br+O 3  BrO +O 2 BrO +BrO  2 Br+O 2 Br+ HCHO  HBr+HCO Br+ HCHO  HBr+HCO Role of Formaldehyde in Ozone Destruction

11. O 3, *20 NO y PAN NO x

12. Vertical HONO profile at SST, 10:00-14:30, 4/24/00. -10 10 30 50 70 90 110 010203040506070 HONO, ppt Height/Depth, cm Courtesy: X. Zhou, SUNYA

13. Courtesy: Schroeder and Steffen, MSC

14. Courtesy: Anlauf and Hayden, MSC Similarly, ozone depletion in spring is an annually recurring phenomenon (for a graphic representation contact Dr. K.G. Anlauf at the Meteorological Service of Canada, Toronto, Ontario, Canada)

15. From: Steffen et al., 2002 TGM at Ice Camp

16. Height (m) Fuentes, unpublished

17. From: Albert et al., 2002

18. Courtesy: Strong and Fuentes

19. From: Bottenheim et al., 2002

20. Some future experiments Detailed chemistry profiles of the lower atmosphere (< 100 m) R ole of frost flowers on chemical processing L aboratory experiments devoted to the heterogeneous chemistry on frozen seawater surfaces Other? (discuss at meeting on Saturday evening) Three-dimensional studies to investigate the climate impact of ozone depletion

21. `