1. Institute for Atmospheric and Climate Science; ETH Zurich; Zurich Switzerland
2. Aerological Station; Federal Office of Meteorology and Climatology MeteoSwiss; Payerne Switzerland
3. Meteorologisches Observatorium Lindenberg, Deutscher Wetterdienst; Lindenberg Germany
4. Federal Office of Meteorology and Climatology MeteoSwiss; Zurich Switzerland
5. Institute of Applied Physics; University of Bern; Bern Switzerland
6. Physikalisch-Meteorologisches Observatorium Davos; World Radiation Center; Davos Switzerland