Nikolina Ban, ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland, Roman Brogli, ETH Zurich, Zurich, Switzerland, Nico Kröner, South Pole, Zürich, Switzerland, Zurich, Switzerland, David Leutwyler, ETH Zurich, Atmospheric and Climate Science, Zurich, Switzerland; MPI Hamburg Max-Planck-Institute for Meteorology, Hamburg, Germany and Christoph Schar, ETH Zurich, Atmospheric & Climate Science, Zurich, Switzerland