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 turbulen ce in Athens, Greece covering a typical late-summer period with prevai ling northerly wind. The wind climatology study shows a distinct diffe rence between the northern and southern parts of the urban area. In th e northern part of Athens the northerly flows (315 degrees-45 degrees) occur more than 60% of the time and the winds from all other directio ns are equally frequent (about 5% per 30 degrees sector). In the south ern part of Athens the northerly flows are more than 50%, but southerl y flows (165 degrees-225 degrees) occur about 25% of the time indicati ng sea breeze development. The variability of the flow characteristics in the whole area was classified into three categories: northerly win ds in the whole Athens bar:in; 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 par ameters over the area. A model of the internal boundary layer height o ver an area with irregular coastline (Gryning and Batchvarova (1996) B oundary Layer Meteorology 78, 405-413) is applied for an Athens site a nd the results are in good agreement with the measurements. (C) 1998 P ublished by Elsevier Science Ltd. All rights reserved.