Exploring the urban boundary layer by sodar and tethersonde

The Austrian city of Graz at the south-eastern edge of the Alps frequently experiences wintertime stagnations during anticyclonic flow conditions, lea ding to high local concentrations of primary pollutants. This paper compare s instrument performance during a representative January stagnation period in 1998 in the Graz region using data obtained from a field experiment that supplemented the routine meteorological network with an array of sodars an d tethersondes and a meteorological tower. Although sodars are known to giv e reliable estimates of the horizontal wind in most cases, direct compariso ns to other instruments for verification are still not very frequent. There fore, the performance of the sodars to detect important modifications to th e wind field over Graz will be discussed and compared to that of the tether sondes and the tower. (C) 2001 Elsevier Science Ltd. All rights reserved.