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List of Abstracts 165number of gases including Carbonyl Sulfide.P-Observations 2.5 ID:4461 10:30Pilot Study Preliminary Results for a Marine Boundary Layer Site near Ucluelet on Vancouver IslandCorinne Schiller, Roxanne Vingarzan, Keith Jones, Anne Marie Macdonald, Richard LeaitchEnvironment CanadaContact: Corinne.Schiller@ec.gc.caA one year pilot study is taking place from April 2010 to April 2011 on the west coast of Vancouver Islandto determine its feasibility as a Marine Boundary Layer (MBL) site. The MBL site is located at AmphitritePoint on Vancouver Island (48.9217, -125.5411) at an elevation of about 20 meters above sea level. Due tothe Beaufort Mountain range bisecting Vancouver Island from NW to SE, the winds in the region arepredominantly parallel to the island or WNW in the summer and ESE in the winter. Back trajectories showthat transpacific air should impact the site on the majority of days with typical meteorological patterns.Occasionally air reaching the site may be impacted by the Seattle area or the Vancouver area. Measurementsat the site include particulate as well as gas samples. Preliminary data from the spring 2010 will bepresented.P-Observations 2.6 ID:4292 10:30Characterisation of the Cape Verde Observatory's air mass origin and chemistry using the NAMEdispersion modelZoë Fleming 1 , Paul Monks 2 , Roland Leigh 3 , Katie Read 4 , Lucy Carpenter 5 , Luis Mendes 61 National Centre for Atmospheric Science, University of Leicester, UK2 Department of Chemistry, University of Leicester, UK3 Earth Observation Science, Department of Physics & Astronomy, University of Leicester, UK4 National Centre for Atmospheric Science, Department of Chemistry, University of York, UK5 Department of Chemistry, University of York, UK6 Instituto Naçional de Meteorologia and Geofisca (INMG), Delegação de São Vicente, Cape VerdeContact: zf5@le.ac.ukThe UK Met office’s NAME atmospheric dispersion model has been used to develop station footprints forthe Humberto Duarte Fonseca WMO Global Observatory on the Cape Verde islands in the Atlantic Ocean.The model output has been run every 3 hours over a period of three years, tracking air mass origin over theprevious 10 days. The most common air mass trajectories types have been identified and each back run wasassigned to one trajectory type.The long term trace gas measurements at Cape Verde from the past three and a half years were used tocalculate an average composition (of O3, NO2, CO, CN, VOCs etc.) for each type of trajectory over thewhole period. Saharan dust episodes are particularly common at the station during the winter months but airfrom the coastal areas just off the African continent are the main route to the islands all year round. Many airmasses originate from North America or from Europe a few days before and tracking the pollutant loadingsof these gives us an idea of the extent of the oxidation that occurs during transport. This seasonal andgeographical characterisation of the chemistry of the air masses arriving at the Cape Verde islands canelucidate the long term pathways and transformations of pollution across the Atlantic Ocean.iCACGP-IGAC 2010 14 July, 2010