Impact of Halogens on Gas-Phase NMOCs in the Arctic Troposphere

The Trace Organic Gas Analyzer (TOGA) was used to measure 25 non-methane organic compounds (NMOCs) near Barrow, Alaska during spring 2009 as part of the OASIS-Barrow study. Samples were taken at a frequency of up to once every five minutes, rotating from several sampling inlets on a 6-m tower for the duration of the study, as well as from a tethered balloon during one week in April. These data, which include observations of oxygenated NMOCs, halogenated NMOCs and non-methane hydrocarbons, were accompanied by whole air canister measurements of these and other NMOCs. Measurements of a number of chemically important gas-phase species as well as meteorological parameters were also obtained, resulting in a comprehensive characterization of the vertical structure of the lower atmosphere. Using observations from the tower, fluxes for many of the NMOCs measured by TOGA were calculated. A number of partial and near-complete ozone depletion events (ODEs) occurred during the 6 week study, providing an opportunity to investigate the chemistry of NMOCs during ODEs. The impact of halogen chemistry on observed NMOCs and fluxes during the ODEs contrasted with the boundary-layer chemistry of the non-ODE periods will be presented.