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List of Abstracts 43parameterizations that can be applied in atmospheric chemistry models. In an effort to fill this gap, weperformed continuous measurements of nitrogen oxides and ozone in the firn air and above the snowpack atSummit, Greenland from summer 2008 to summer 2010. These observations have shown strong diurnal andseasonal patterns for NOx, with evidence of a very different behavior and magnitude in concentrations forNO and NO2. Diurnal cycles are observed in and above the snowpack, as high as 9 m, showing the influenceof snowpack emissions on the overlying atmosphere. These new chemical observations and supportingmicrometeorological variables are now being applied to develop a more mechanistic representation ofcryosphere-atmosphere reactive trace gas exchange in a chemistry-climate model. This will allow us toassess the significance of cryosphere-atmosphere chemical exchange in tropospheric chemistry underclimate and global change.P-Interfaces.7 ID:4155 15:35A network of autonomous surface ozone monitors in Antarctica: technical description and firstresults.Stephane Bauguitte, Neil Brough, Markus Frey, Anna Jones, Howard Roscoe, Eric WolffBritish Antarctic SurveyContact: h.roscoe@bas.ac.ukConcentrations of surface ozone in polar regions cannot be derived from satellite data, so must be measuredby ground-based sensors. To understand the regional picture a carefully designed network of sensors isrequired. Here we report on a network of 10 autonomous ozone monitors, deployed in the Weddell Seasector of coastal Antarctica plus inland towards the Antarctic Plateau. Measurements were made for a fullyear. Each ozone monitor measured successfully within its predefined duty cycle throughout the year, withsome differences in performance dependent on power availability and air temperatures, which we discuss.Preliminary results show that on several occasions the same ozone depletion event was observed by manymonitors covering much of the region. The results also allow us to explore regional differences in ozoneenhancements due to photolysis of nitrate in snow during early summer, and in ozone loss that might berelated to the supply of halogens during late summer.P-Interfaces.8 ID:4464 15:35Uptake and reactivity of hydroxyl radicals on iceTara Kahan 1 , Jordan Vincent 1 , Ran Zhao 2 , D.J. Donaldson 2 , John Hemminger 1 , Douglas Tobias 11 University of California at Irvine2 University of TorontoContact: tkahan@chem.utoronto.caIce surfaces are important substrates for atmospheric chemistry. Reactions in ice are expected to occurprimarily in the disordered region near the air-ice interface known as the quasi-liquid layer (QLL). Both thephysical properties of the QLL and its role in reaction mechanisms and kinetics are poorly understood.Although there are some similarities between the QLL and liquid water, reaction kinetics often differ greatlyin the two environments. Using a surface-sensitive spectroscopic probe, we measured kinetics of reactionsbetween hydroxyl radicals and aromatic hydrocarbons in aqueous solution and at air-ice interfaces.Reactions proceeded as expected in aqueous solution, but were significantly suppressed on ice, both whenOH was formed from the photolysis of precursor compounds present at the air-ice interface, and when it wasintroduced from the gas phase. To better understand this observed lack of reactivity, we studied theadsorption of hydroxyl radicals to air-ice and air-water interfaces using molecular dynamics.iCACGP-IGAC 2010 12 July, 2010