Firstly, the ability to directly measure CO2 with traditional remote sensing techniques is difficult, primarily because of the very high atmospheric background levels of the gas! We therefore combined the use of ultra-violet cameras (for more info see Mori and Burton, 2006) to measure SO2 and an instrument called a Multi-GAS analyser (for more info see Aiuppa et al. 2005) which has the ability to measure CO2/SO2 ratios. We can then combine the two sources of data to produce a CO2 flux series.
Below is the "AudioSlides" presentation created for the paper, which is great by the way, it has to be less than 5 minutes long and certainly condenses any paper into an easily digestible format, I would certainly encourage others to do something similar!