This paper helps establish a range of new applications for compact solar-tracking Fourier transform spectrometers, and shows the capability of differential column measurements for determining urban emissions. By accurately measuring the differences in the integrated column amounts of carbon dioxide and methane across local and regional sources in California, we directly observe the mass loading of the atmosphere due to the influence of emissions in the intervening locale.

http://www.atmos-chem-phys.net/16/8479/2016/acp-16-8479-2016.html