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List of Abstracts 44P-Interfaces.9 ID:4349 15:35Modelling of polar emissions of NOx from snowpack and its impact on polar bromineGlenn Carver 1 , Xin Yang 1 , Eric Wolff 2 , Anna Jones 2 , Apostolos Voulgarakis 31 Centre for Atmospheric Science, University of Cambridge, UK2 British Antarctic Survey, UK3 NASA Goddard Institute for Space Studies, Center for Climate Systems Research, USAContact: Glenn.Carver@atm.ch.cam.ac.ukMeasurements in recent years show that several species, important for the oxidizing capacity in thetroposphere, are emitted by snow in polar regions and other snow covered areas of the world. We have usedthe Cambridge chemical transport model, p-TOMCAT to study the impact of emission of NOx from thesnowpack. A parametrization of the production of NOx by photolysis of snowpack nitrate has beendeveloped and used with an assumed global nitrate inventory. Multiannual integrations show that NOxemissions from snow have a small impact globally but represent a significant source of NOx in the polarregions.It is well established that ‘bromine explosion’ events occur regularly in the polar regions with large areas ofelevated BrO observed around the sea-ice. In previous work, we have also developed parametrizations forthe heterogeneous production of bromine from snow-sourced sea-salt and snow that can reproduceobservations in model simulations using p-TOMCAT. In this paper we report on work in which the impactof the NOx release from snow on the polar bromine chemistry is assessed, particularly with respect to theformation and distribution of BrONO2 and how it alters the ozone budget.P-Interfaces.10 ID:4495 15:35Bromine Cycling in Snow, Firn Air, and the Atmospheric Boundary Layer at Summit, GreenlandDuring the GSHOx Field CampaignJennie Thomas 1 , Jochen Stutz 1 , Jack Dibb 2 , Roland Von Glasow 31 Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles2 Institute for the Study of Earth, Oceans, and Space, University of New Hampshire3 School of Environmental Sciences, University of East AngliaContact: r.von-glasow@uea.ac.ukSunlit snow and ice are known to play an important role in determining the chemical composition of theArctic boundary layer, for example ice chemistry is important for boundary layer ozone depletion events atpolar sunrise. In remote Arctic regions pollutants originating mainly from lower latitudes react with variousatmospheric radical species potentially impacting the ozone budget and oxidizing elemental mercury.Despite the important role of atmospheric chemistry in the Arctic, our understanding of the underlyingchemical transformations in the remote snow pack and its impact on the fate of air pollutants is incomplete.Motivated by indirect evidence that reactive halogens are present on the Greenland ice sheet, two fieldcampaigns have been conducted at Summit, Greenland in 2007 and 2008 to study air and snow properties.Our measurements identified BrO mixing ratios of up to 3ppt with typical levels in the range of 1 - 2ppt.Peaks in soluble gaseous bromine generally occurred 1-3 days after free troposphere air above Summitpenetrated the stable surface boundary layer which resulted in increased concentrations of bromide in surfacesnow.We have also developed a new vertically resolved model for snow physics and chemistry in order tounderstand the chemical and physical processes occurring during these field experiments. BothiCACGP-IGAC 2010 12 July, 2010