The SP-AMS Inter-Comparison Campaign. AMEWU A. MENSAH, Joel Corbin, Sanna Saarikoski, Axel Eriksson, Martin Gysel, Raphael Färber, Berko Sierau, Manuel Abegglen, Veronika Hladnik, André Welti, Ulrike Lohmann, ETH Zurich, Institute for Atmospheric & Climate Science