1. Department of Applied Physics, Laboratory of Meteorology, University of Athens, Ippokratous 33, 10680 Athens, Greece
2. Department of Applied Physics, Laboratory of Meteorology, University of Athens, Ippokratous 33, 10680 Athens, Greece; Institute of Meteorology and Physics of the Atmospheric Environment, National Observatory of Athens, P. 0. Box 20048, 11810 Thisio, Athens, Greece
3. Institute of Meteorology and Physics of the Atmospheric Environment, National Observatory of Athens, P. 0. Box 20048, 11810 Thisio, Athens, Greece