Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 6 6 2006 10.5194/acpd-6-11051-2006 http://www.atmos-chem-phys-discuss.net/6/11051/2006/ http://www.atmos-chem-phys-discuss.net/6/11051/2006/acpd-6-11051-2006.html http://www.atmos-chem-phys-discuss.net/6/11051/2006/acpd-6-11051-2006.pdf 11051 11066 2006-11-07 First-year sea-ice contact predicts bromine monoxide (BrO) levels better than potential frost flower contact W. R. Simpson ffwrs@uaf.edu D. Carlson G. Hoenninger T. A. Douglas M. Sturm D. Perovich U. Platt Geophysical Institute and Department of Chemistry, University of Alaska Fairbanks, Fairbanks, AK 99775-6160, USA Institute for Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany U.S. Army Cold Regions Research and Engineering Laboratory, P.O. Box 35170, Fort Wainwright, AK 99703-0170, USA deceased Reactive halogens are responsible for boundary-layer ozone depletion and mercury deposition in Polar Regions during springtime. To investigate the source of reactive halogens in the air arriving at Barrow, Alaska, we measured BrO, a marker of reactive halogen chemistry, and correlated its abundance with airmass histories derived from meteorological back trajectories and remotely sensed sea ice properties. The BrO is found to be positively correlated to first-year sea-ice contact (<i>R</i>²=0.55), and weakly negatively correlated to potential frost flower (PFF) contact (<i>R</i>²=0.04). These data indicate that snow contaminated with sea salts on first-year sea ice is a more probable bromine source than are frost flowers. Recent climate-driven changes in Arctic sea ice are likely to alter frost flower and first year sea ice prevalence, suggesting a significant change in reactive halogen abundance, which will alter the chemistry of the overlying Arctic atmosphere.