Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland

Finnish Meteorological Institute, P.O. Box 1627, 70211 Kuopio, Finland

Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland

Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland

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

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA

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

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA