Description:
<jats:title>Abstract</jats:title>
<jats:p>Total columns of C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>, C<jats:sub>2</jats:sub>H<jats:sub>6</jats:sub>, CH<jats:sub>4</jats:sub>, CH<jats:sub>3</jats:sub>OH, CO, H<jats:sub>2</jats:sub>CO, HCl, HCN, HCOOH, HF, HNO<jats:sub>3</jats:sub>, N<jats:sub>2</jats:sub>O, NH<jats:sub>3</jats:sub> and O<jats:sub>3</jats:sub> were retrieved from 2002-2019 using a Fourier transform infrared (FTIR) spectrometer at the University of Toronto Atmospheric Observatory (TAO). Trends and enhancement events were determined by fitting trended Fourier series, and bootstrapping was used to identify the statistical significance. Trends from 2002 to 2019 (%/year, with 2<jats:italic>σ</jats:italic>uncertainties) were found for C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> (−1.12 ± 0.30), C<jats:sub>2</jats:sub>H<jats:sub>6</jats:sub> (−0.74 ± 0.73 from 2002–2008 and 1.19 ± 0.27 from 2009–2019), CH<jats:sub>4</jats:sub> (0.26 ± 0.10 from 2002–2008 and 0.41 ± 0.03 from 2009–2019), CO (−0.90 ± 0.07), HCN (−0.51 ± 0.21), HCOOH (−2.15 ± 0.64), HF (0.59 ± 0.11), HNO<jats:sub>3</jats:sub> (0.36 ± 0.13), N<jats:sub>2</jats:sub>O (0.28 ± 0.02), NH<jats:sub>3</jats:sub> (3.56 ± 0.85), and O<jats:sub>3</jats:sub> (0.28 ± 0.19 and −0.05 ± 0.07 for tropospheric and stratospheric columns, respectively). The GEOS-Chem chemical transport model showed that wetland emissions were the largest contributor to CH<jats:sub>4</jats:sub> columns measured at TAO (average relative contribution of 31.7%), and that CH<jats:sub>4</jats:sub> oxidation was a major source of CO (accounting for 30.9%).</jats:p>