The choice of path length and retroreflector array size in open-path Fourier transform infrared spectroscopy must be made with care.  Longer paths increase target gas absorption (lowering detection limits), and larger retroreflector arrays increase the return signal (improving retrieved concentration precision), but there are limitations to both. An optimum array size and path combination exists in each specific observational environment and application, as explored in this work.

Using 20 years of high-resolution satellite data, we present quantitative evidence that High-Latitude Dust (HLD) sources to the atmosphere are widespread across the "Canadian Arctic Dust Belt". Our results motivate atmospheric model development to include HLD sources, while our data provides an observational basis for evaluating such improved models. The Arctic is a fragile region experiencing 3–4 greater warming than global average and HLD is of significance to that warming.

Nineteen years of atmospheric composition measurements made at the University of Toronto Atmospheric Observatory (TAO; 43.66° N, 79.40° W; 174 m.a.s.l.) are presented. These are retrieved from Fourier transform infrared (FTIR) solar absorption spectra recorded with a spectrometer from May 2002 to December 2020. The retrievals have been optimized for fourteen species: O₃, HCl, HF, HNO₃, CH₄, C₂H₆, CO, HCN, N₂O, C₂H₂, H₂CO, CH₃OH, HCOOH, and NH₃.