Wind climatology, atmospheric turbulence and internal boundary-layer development in Athens during the MEDCAPHOT-TRACE experiment

This paper presents an analysis of wind field and atmospheric turbulence in Athens, Greece 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 urban area. In the northern part of Athens the northerly flows (315°–45°) occur more than 60% of the time and the winds from all other directions are equally frequent (about 5% per 30° sector). In the southern part of Athens the northerly flows are more than 50%, but southerly flows (165°–225°) occur about 25% of the time indicating sea breeze development. The variability of the flow characteristics in the whole area was classified into three categories: northerly winds in the whole Athens basin; sea breeze throughout the whole Athens basin; and changing sea breeze (comprising partial penetration of the sea breeze over the city and/or changing wind direction throughout the day). This classification was used as basis for the investigation of the atmospheric turbulence and vertical profiles of meteorological parameters over the area. A model of the internal boundary layer height over an area with irregular coastline (Gryning and Batchvarova (1996)Boundary Layer Meteorology 78, 405–413) is applied for an Athens site and the results are in good agreement with the measurements.