Infrared Hyperspectral and Ultraviolet Remote Measurements of Volcanic Gas Plume at MT Etna during IMAGETNA Campaign

Quantification of gaseous emission fluxes from volcanoes can yield valuable insights on
processes occurring in the Earth’s interior as part of hazard monitoring. It is also an important task in
the framework of climate change, in order to refine estimates of natural emissions. Passive open-path
UltraViolet (UV) scattered observation by UV camera allows the imaging of volcanic plumes and
evaluation of sulfur dioxide (SO2) fluxes at high temporal resolution during daytime. Another
technique of imaging is now available in the InfraRed (IR) spectral domain. Infrared hyperspectral
imagers have the potential to overcome the boundary of daytime sampling of the UV, providing
measurements also during the night and giving access simultaneously to additional relevant gas
species. In this context the IMAGETNA campaign of measurements took place at Mt Etna (Italy) in
June 2015. Three di erent IR imagers (commercial and under developments) were deployed, together
with a Fourier Transform InfraRed spectrometer (FTIR) instrument, a UV camera, a LongWavelength
InfraRed (LWIR) camera and a radiometer. We present preliminary results obtained by the two IR
cameras under development, and then the IR hyperspectral imager results, coming from full physics
retrieval, are compared to those of the UV camera. The comparison points out an underestimation of
the SO2 Slant Column Densities (SCD) of the UV camera by a factor of 3.6. The detailed study of the
retrieved SO2 SCD highlights the promising application of IR imaging in volcanology for remotely
volcanic plume gas measurements. It also provides a way to investigate uncertainties in the SO2 SCD
imaging in the UV and the IR.