IPY: Halogen Chemistry and Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) Chemical Exchange During IPY

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The objective of this project is to develop a novel instrument for ultra-trace level determination of the halogen atom (Cl, Br, and I) and radical (ClO, BrO and IO) concentrations in the air above the Arctic Ocean. The development of the instrument will help to address the hypothesis that halogen atom chemistry derived from salt associated with the surface of the sea ice has a very large impact on the oxidizing power of the Arctic atmospheric boundary layer. This in turn results in production of cloud condensation nuclei, which in turn influence cloud cover. However, the ability to directly measure halogen atom concentrations needs to be developed, so that this important chemistry (that results in rapid depletion of ozone and mercury during Arctic spring) can be monitored as sea ice cover changes in the coming decades. The instrument to be developed involves sampling air into a quartz flowtube, in which the halogen atoms react rapidly with trifluoropropene, to produce a halogenated ketone that can be detected with great sensitivity using chromatographic techniques. During this project the development of this field-calibrated method will be completed, and it will be implemented in a variety of polar marine environments during the International Polar Year. Fieldwork will be done aboard the Canadian icebreaker 'Amundsen' in spring 2008 and the Swedish icebreaker 'Oden' in summer 2008, and at Barrow and a pack ice camp in early spring 2009. Interpretation of the field measurements will be aided by 1-D, multiphase, numerical modeling of interactions among reactive species, and mixing and transport. An important outcome of the project will be a fully-tested, robust, portable sampling device that will facilitate long-term measurements of halogen atom chemistry as part of the Arctic Observing Network as the sea ice cover in the Arctic changes. Broader impacts include (1) participation in the fieldwork of a writer, Peter Lourie, who is planning to write a book about global climate change, and (2), development of public outreach and graduate courses related to Arctic climate change in partnership with the Purdue Climate Research Center.