1. Université Clermont Auvergne, INRAE, PIAF , 63000 Clermont-Ferrand , France
2. Institute for Atmospheric and Earth System Research/ Physics, Faculty of Science, University of Helsinki , Finland
3. Institute for Atmospheric and Earth System Research/ Forest Science, Faculty of Agriculture and Forestry, University of Helsinki , Finland
4. Institute for Botany, University of Innsbruck , Austria
5. Department of Physics, University of Helsinki , Finland