Meteorological Measurements, Wind Climatology, Atmospheric Turbulence and Internal Boundary Layer Development in Athens during the Medcaphot-Trace Experiment

This report presents an analysis of wind field and atmospheric turbulence in the Athens area covering a typical late summer period with prevailing northerly wind. The wind climatology study shows a distinct difference between the northern and southern parts of the area. In the northern part of Athens the northerly flows (315 - 45 degrees) are more than 60 % and the winds from all other directions are equally frequent (about 5 % per 30 degrees sector). In the southern part of Athens the northerly flows are more than 50 %, but southerly flows (165 - 225 degrees) occur about 25 % of the time indicating sea breezes development. The variability of the flow characteristics ni the whole area was classified into three categories: northerly winds in the whole Athens basin; sea breeze throughout the whole Athens basin; and sea breeze penetration to the center of the city. This classification was used as basis for the investigation of the atmospheric turbulence and vertical profiles of meteorological parameters over the area. Examples of internal boundary layer formation over the Athens area, based on measurements and model calculations, are discussed. Mainly data from the meteorological measuring stations operated by Risø National Laboratory during the MEDCAPHOT-TRACE Experiment (26 August - 18 September 1994) are used for this study.