FTS measurements of column CO 2 at Sodankylä

7 Fourier Transform Spectrometer (FTS) observations at Sodankylä, Finland (67.4o N, 26.6 o E) 8 have been performed since early 2009. The FTS instrument is participating in the Total 9 Carbon Column Observing Network (TCCON) and has been optimized to measure 10 abundances of the key greenhouse gases in the atmosphere. Sodankylä is the only TCCON 11 station in the Fennoscandia region. Here we report the measured CO2 time series over a seven 12 year period (2009-2015) and provide a description of the FTS system and data processing at 13 Sodankylä. We find the lowest monthly column CO2 values in August and the highest 14 monthly values during the February to May season. Inter-annual variability is the highest in 15 June-September period, which correlates with the growing season. During the time period of 16 FTS measurements from 2009 until 2015 we have observed a 2.2+/-0.2 ppm increase per year 17 in column CO2. The monthly mean column CO2 values have exceeded 400 ppm level for the 18 first time in February 2014. 19