Royal Meteorological Institute of Belgium, Dept. of Observations, Avenue Circulaire 3, 1180 Brussels, Belgium

Royal Meteorological Institute of Belgium, Dept. of Observations, Avenue Circulaire 3, 1180 Brussels, Belgium

Hong Kong Polytechnic University, Dept. of Civil and Structural Engineering, Hong Kong

Yonsei University, IEAA BK21 Program, Global Environment Laboratory, Department of Atmospheric Science, Seoul, Korea

Environnement Canada, Experimental Studies Section, Science and Technology Branch, 4905 Dufferin Street, M3H 5T4, Toronto, ON, Canada,

Department of Physics, University of Rome "La Sapienza", P. le Aldo Moro, 200185 Rome, Italy

Royal Meteorological Institute of Belgium, Dept. of Observations, Avenue Circulaire 3, 1180 Brussels, Belgium