Atmospheric Carbon Dioxide and Methane measurements at Sodankylä, Finland

Carbon dioxide and methane column measurement at the Finnish Meteorological Institute’s Sodankylä facility in northern Finland started in early 2009. The measurements have been taken by a Fourier Transform Spectrometer (FTS) in the near-infrared spectral region. From the spectra column-averaged abundances of CO₂, CH₄ and other gases are derived. The instrument participates in the Total Carbon Column Observing Network (TCCON).  Here we present long-term ground based FTS measurements of carbon dioxide and methane and comparisons with satellite borne observations. We find that CO₂ column amounts have increased by 2.2 ± 0.1 ppm/year since the start of the measurements in 2009 and CH₄ column amounts have increased by 7 ± 0.4 ppb/year. The measurements are in good agreement with multi-year measurements by the Greenhouse Gases Observing Satellite (GOSAT): the relative difference in XCH₄ has been -0.07 ± 0.02 % and the relative difference in XCO₂ has been 0.04 ± 0.02 %. Finally we use balloon borne AirCore observations at the Sodankylä site to provide comparisons between FTS and in situ observations during all seasons.