1. Finnish Meteorological Institute, Helsinki, Finland;
2. Meteorology and Air Quality, Wageningen University & Research, Wageningen, The Netherlands;
3. SRON Netherlands Institute for Space Research, Utrecht, The Netherlands;
4. Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands;
5. Centre for Isotope Research, Energy and Sustainability, Research Institute Groningen, Groningen University, Groningen, The Netherlands;
6. Climate and Environmental Physics, Physics Institute & Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland;
7. Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden;
8. Department of Geosciences and Natural Resource Management, Center for Permafrost (CENPERM), University of Copenhagen, Copenhagen, Denmark;
9. Department of Applied Physics, University of Eastern Finland, Kuopio, Finland;
10. University of Helsinki, Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/Physics, University of Helsinki, Finland;
11. University of Helsinki, Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, Finland;
12. Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, CO, USA;
13. Max Planck Institute for Biogeochemistry, Jena, Germany;
14. College of Life and Environmental Sciences, University of Exeter, Exeter, UK;
15. Meteorological State Agency of Spain (AEMET), Tenerife, Spain