The site at Sodanklya is run by the Finnish Meteorological Institute. Tedlar bag samples are made from a 50m mast in a small forested area.
There is a continuous record of methane and carbon dioxide concentrations measured since 2012 and a range of supporting measurements.
Samples are also collected weekly and returned to Royal Holloway for methane concentration and methane carbon isotope analysis.
More information is at: http://en.ilmatieteenlaitos.fi/GHG-measurement-sites#Sodankyla_forest