A climatological analysis of four-day back trajectories from aliartos, Greece

This study presents a flow climatology for Greece based on a survey of climate and synoptic weather types, and a five-year trajectory climatology. Isobaric back trajectories at the 850 and 700 hPa levels were calculated daily at 0 and 12 Z for the years 1983–1987 for the Aliartos, Greece EMEP station, using the Air Resources Laboratory (ARL) trajectory model. Trajectories were classified by direction and speed to examine monthly, seasonal and annual variability in flow characteristics. The main features of the flow are similar from year to year. Dominant transport sectors are NW and W, followed by N, SW and NE. Four-day back trajectories from NW and W usually originate from beyond 2,400 km, while those from other directions tend to originate closer to Greece. Cases of most rapid transport occur in January and December. Potential pollutant source regions are identified corresponding to preferred trajectory directions and distance ranges.