4 M. Petrillo, P. Cherubini, G. Fravolini, M. Marchetti, J. Ascher, M. Schärer, H.-A. Synal, D. 5 Bertoldi, F. Camin, R. Larcher, and M. Egli 6 7 Department of Geography, University of Zurich, 8057 Zurich, Switzerland 8 WSL Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, 9 Switzerland 10 Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich, Switzerland 11 D...