MEASUREMENTS ON THE DISTRIBUTION OF TRACE SUBSTANCES IN THE ARCTIC TROPOSPHERE

During the 'Arctic Haze' measuring campaign in March-April 1994 and th e 'Merisec' measuring campaign in June 1994 the horizontal and vertica l variations of O-3-, SO2-, PAN-, HNO3-, nitrate- and sulfate-concentr ations were measured. Eight representative measuring flights are prese nted. The aircraft observations showed that ozone depletion is occurri ng beyond the Arctic inversion layer during April and June. Ozone conc entrations generally increased significantly with altitude. NO values were always below the detection limit. HNO, was accumulated on impregn ated filters instead of commonly used nylon filters. Only impregnated cellulose filters exhibit high collection efficiencies at low contents of atmospheric water vapor. For measuring SO2 a sensitive filter tech nique was applied. The mixing ratio of SO2 seldom exceeded the value o f 200 pptv in April 1994 (150 pptv in June 1994). The concentrations s howed no continuous vertical gradient, but often a layered structure. (C) 1997 Elsevier Science B.V.