Vertical profiles of ozone, water vapor and meteorological parameters and boundary-layer conditions at Summit, Greenland during June 2000

The temporal and spatial distribution of boundary-layer ozone was studied during June 2000 at Summit, Greenland by surface-level measurements and vertical profiling from a tethered balloon. Three weeks of continuous ozone surface data and 133 meteorological and 82 ozone vertical profile data sets were collected from the surface to a maximum altitude of 1400 m above ground. The lower atmosphere at Summit was characterized by the prevalence of high stability conditions with strong surface temperature inversions. These inversions succumbed to neutral to slightly unstable conditions between appr. 9.00 and 18.00 hrs local time with the formation of shallow mixing heights of typically 70-250 m above the surface. Surface ozone ranged from 39 to 68 ppbv and occasionally had rapid changes of up to 20 ppb in 12 hours. The diurnal mean ozone mixing ratio showed distinct cycles indicating meteorological and photochemical controls of surface ozone. Vertical profiles were within the range of 37 to 76 ppb and showed strong stratification in the lower troposphere. A high correlation of high ozone/low water vapor indicated the transport of high tropospheric/low stratospheric air into the lower boundary layer. An appr. 1 to 4 ppb decline of ozone towards the surface was frequently observed within the neutrally stable mixed layer during midday hours. These observations suggest that the boundary-layer ozone and ozone depletion/deposition to the snowpack are influenced by photochemical processes that follow diurnal dependencies.