The Arctic Outflow Campaign: A Measurement Study to Characterize the Composition and Photochemistry of Arctic Air Transported Southward During Spring

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9528031 Honrath This project consists of a multi-investigator measurement campaign studying the springtime outflow of arctic air toward the North Atlantic. During winter and spring, levels of photochemically active pollutants are elevated in the remote arctic troposphere. Recent work indicates that transport through the Arctic provides a substantial flux of total reactive nitrogen (NOy) and non-methane hydrocarbons to the temperate North Atlantic region. This process may play a significant role in the tropospheric ozone budget of this and other remote regions. Current understanding of these effects is limited by an absence of measurements of the relevant compounds in southward-transported arctic air. The ground-based measurement campaign will take place during January-April, 1996, at a site in Newfoundland, within the dominant pathway of springtime arctic air flow. Measurements will include ozone, nitric oxide, nitrogen dioxide, peroxyacetic nitric anhydride, peroxypropionic nitric anhydride, alkyl nitrates, total reactive nitrogen, non-methane hydrocarbons, carbon monoxide, plus standard meteorological parameters and radiometer-based nitrogen dioxide photodissociation rates. Real-time isentropic back-trajectory forecasts and meteorological analyses will be used to guide the sampling frequency to ensure adequate coverage during outflow events. An archive of back-trajectories will assist in data interpretation. The results of this study will be used to assess the impact of the winter-spring arctic reservoir on the levels and speciation of NOx, NOy, and non-methane hydrocarbons at lower latitudes. Impacts on the local ozone formation/destruction rate and budget will be estimated using a photochemical box model.