(2019-07-20) Chao Zhang; Jon Atherton; Josep Peñuelas; Iolanda Filella; Pasi Kolari; Juho Aalto; Hanna Ruhanen; Jaana Bäck; Albert Porcar‐Castell; Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00014, Finland; CREAF, Center for Ecological Research and Forestry Applications, Bellaterra 08193, Spain; 3CSIC, Global Ecology Unit CREAF‐CSIC‐UAB, Cerdanyola del Vallès 08193, Spain - Chao Zhang; Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00014, Finland - Jon Atherton; CREAF, Center for Ecological Research and Forestry Applications, Bellaterra 08193, Spain; 3CSIC, Global Ecology Unit CREAF‐CSIC‐UAB, Cerdanyola del Vallès 08193, Spain - Josep Peñuelas; CREAF, Center for Ecological Research and Forestry Applications, Bellaterra 08193, Spain; 3CSIC, Global Ecology Unit CREAF‐CSIC‐UAB, Cerdanyola del Vallès 08193, Spain - Iolanda Filella; Department of Physics, University of Helsinki, Helsinki 00014, Finland - Pasi Kolari; Department of Physics, University of Helsinki, Helsinki 00014, Finland; Station for Measuring Forest Ecosystem– Atmosphere Relations II (SMEAR II), Hyytiälä Forestry Field Station, University of Helsinki, Korkeakoski 35500, Finland - Juho Aalto; Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Suonenjoki 77600, Finland - Hanna Ruhanen; Department of Forest Sciences, University of Helsinki, Helsinki 00014, Finland - Jaana Bäck; Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00014, Finland - Albert Porcar‐Castell