Five day 3D back trajectory clusters and trends analysis of the Uccle ozone sounding time series in the lower troposphere (1969–2001)

• Published in: Atmospheric environment (1994) Vol. 42; no. 19; pp. 4419 - 4432
• Main Authors: Delcloo, Andy W., De Backer, Hugo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2008; Elsevier Science
• Subjects: 3D back trajectories; Applied sciences; Atmospheric pollution; Cluster; Exact sciences and technology; PBL; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Trends; Tropospheric ozone; Belgium; Europe; North America; Cluster; Tropospheric ozone; PBL; Trends; 3D back trajectories; Cluster analysis; Stratosphere troposphere coupling; Atmospheric condition; Photochemical oxidants; Pollutant formation; Environmental factor; Ozone; Secondary pollutant; Review; Atmospheric sounding; Atmospheric dynamics; Air mass; Seasonal variation; Atmospheric boundary layer; Trend analysis; Air pollution; Time-series analysis; Trajectory
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2008.01.072

Five day 3D back trajectories have been calculated for air parcels arriving at different pressure levels at Uccle (Belgium, 50 ∘ 48 ′ N , 4 ∘ 21 ′ E , 100 m asl) for the time period 1969–2001 on days where an ozone sounding took place. The trajectory model used is the APTRA model, available at the European Centre for Medium-Range Weather Forecasts (ECMWF). A nonhierarchical clustering method has been applied on the obtained 3D back trajectories in function of the season for the planetary boundary layer (PBL) and the lower free troposphere (LFT) to identify natural clusters of air masses. It was possible to derive distinctive clusters of air masses for every season. In the spring season, a reduction in ozone concentrations in the PBL within slow moving air masses from the west, combined with an increase in the frequency of occurrence, seems to be compensated by a positive trend in ozone concentrations at Uccle within the other source regions, mainly within the cluster representing slow moving air masses over the continent. More inflow from North America has been detected during the winter season, resulting in higher ozone concentrations in the PBL.