1. Institute of Environmental Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany;
2. Institute for Atmospheric Physics, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 21, 55099 Mainz, Germany;
3. Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany;
4. Jet Propulsion Laboratory, California Institute of Technology (Caltech), 4800 Oak Grove Drive, 91109 Pasadena, California, USA;
5. Faculty of Sciences, University Mohammed I, B.P. 524, Oujda 60000, Morocco