The Walker et al. (2011, 2012) linear retrieval developed for the Infrared Atmospheric Sounding Interferometer (IASI) on the Metop satellites has been used to process the IASI Metop-A data to produce an effect SO2 column amount. The linear retrieval output for each orbit has then been averaged for each month to obtain an average effective SO2 column amount in Dobson Units (DU). In this application, the retrieval uses the ν3 absorption band (centred at 7.3 μm) and SO2 was assumed to be evenly distributed between the surface and 20 km.

Literature: Taylor et al. (2018) Exploring the utility of IASI for monitoring volcanic SO2 emissions, in review at JGR: Atmospheres. Walker et al. (2011) An effective method for the detection of trace species demonstrated using the MetOp Infrared Atmospheric Sounding Interferometer, Atmospheric Measurement Techniques, 4: 1567-1580, doi:10.5194/amt-4-1567-2011. Walker et al. (2012) Improved detection of sulphur dioxide in volcanic plumes using satellite-based hyperspectral infrared