A ohne-year record of ozone profiles in an alpine valley (Zillertal/Tyrol, Austria, 600-2000 m a.s.L.)

1991

S. 1759-1765

Bandaufführung

55931

Our data, based on ozone records in the year 1987 in an Alpine valley at elevations from 600 m to 2000 m a.s.l. indicate the existence of increased ozone levels from March to September in the experimental region. These levels were observed at a height range of 400-1400 m above the floor of the valley and exhibit monthly averaged ozone values of typically 5-20 ppbv above the "mid-tropospheric" (3000 m a.s.l.) concentrations. The excess ozone gives evidence for an additional effect of local and regional ozone production in addition to the general influx of ozone from the free troposphere. Considering recent views about the historical trends of ozone increase at ground level and in the free troposphere we found that ozone levels at elevated sites in the northern parts of the Eastern Alps have more than doubled since the 1950s. At an elevation of 1000 m a.s.l. in the Zillertal (400 m above the floor of the valley) the increase is near a factor of three.