Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland

Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland

Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 22362 Lund, Sweden

Helsinki Institute of Physics, University of Helsinki, P. O. Box 64, 00014 University of Helsinki, Finland

Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland

Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland

North-Eastern Federal University, 58 Belinskogo st., 677000, Yakutsk, Russia

Institute for Biological Problems of Cryolithozone SB RAS, 41 Lenin Ave., 677980 Yakutsk, Russia

Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland

Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research/Atmospheric Environmental Research, Kreuzeckbahn Str. 19, 82467 Garmisch-Partenkirchen, Germany

Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland