LOWER TROPOSPHERIC STRUCTURE AND SYNOPTIC-SCALE CIRCULATION PATTERNS DURING PROLONGED TEMPERATURE INVERSIONS OVER ATHENS, GREECE

In this paper an attempt is made to detect prolonged (of more than 24 hours duration) temperature inversions in the planetary boundary layer over Athens, to study their main characteristics and to find out the synoptic situations with which the inversions are associated. Given th e close relationship between the synoptic-scale atmospheric circulatio n and the occurrence, maintainance and decay of temperature inversions , a simultaneous three category classification of presented inversions and their respective synoptic situations is presented. The classifica tion relies mainly on the similarities and differences in the formatio n and the maintenance of prolonged temperature inversions. To provide a record of the structure of the lower troposphere and the synoptic co nditions favourable to the formation of inversions, mean ascents of te mperature and dew-point temperature and mean wind profiles for the yea rs 1980-1994 were calculated for each category into which a total of 2 97 cases fell. The main element of this structure which strongly affec ts the pollution of the lower troposphere is the prolonged temperature inversion. Also, for each category, mean 500 and 850 hPa heights and temperature charts, 500 hPa height anomaly charts, mean sea level (MSL ) pressure charts and MSL pressure anomaly charts were drawn.