1. Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany;
2. Meteorological Institute, Ludwig–Maximilians–Universität, Theresienstr. 37, 80333 Munich, Germany;
3. Institute of Atmospheric Physics, German Aerospace Center (DLR), Oberpfaffenhofen, 82234 Wessling, Germany;
4. CNISM–Naples, and Physics Department, University Federico II Naples, Via Cinthia, I-80126 Naples, Italy;
5. Institute for Atmospheric Physics, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany