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 degrees-45 degrees) occur more than 60% of the time 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 degrees-225 degrees) 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 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 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. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.