Case studies of the wintertime convective boundary-layer structure in the urban area of Milan, Italy

The paper describes some aspects of the convective boundary-layer structure based on simultaneous sodar and tethersonde measurements during a field ex periment in the urban area of Milan in the period 8 to 20 February, 1993. D uring this period, fog episodes and strong low-level elevated inversions (w ith lower boundaries < 400 m) were observed most of the time. A close agree ment in the mixing height values, derived from the sodar and tethersonde pr ofiles, has been achieved under these conditions. The validity of the simil arity relationships, which have been originally derived to describe the ver tical velocity variance and heat flux profiles over horizontally homogeneou s terrain under quasi-stationary conditions, was evaluated when applied to the urban boundary layer.