Estimation of SO2 abundance in the eruption plume of Mt. Etna using two MIVIS thermal infrared channels: a case study from the Sicily-1997 Campaign

In this paper, an algorithm is developed basedon the split-window technique, to estimate the SO2 abundancein the plume of Mt. Etna volcano using the multispectralinfrared and visible imaging spectrometer(MIVIS). The MIVIS data were remotely sensed in thethermal infrared (TIR) during the Sicily-1997 Campaign.In this study, the MODTRAN 3.5 code has been used tosimulate the radiance at the sensor; the radiative transfermodel was input along with the data of radio-soundingperformed simultaneously with the MIVIS flight using amobile radio-theodolite. From the SO2 map, derivedfrom the MIVIS image, the SO2 flux along the axis ofthe plume was computed knowing the wind speed at theplume altitude. The SO2 flux is variable along the plumeaxis. The average SO2 flux (about 45 kg s–1 on 12 Juneand about 30 kg s–1 on 16 June) emitted from the vents iscompared with the correlation spectrometer (COSPEC)measurements carried out by other teams (from theground and from a light aircraft flying under the plume)during the MIVIS flight. Finally, by means of this algorithmit should be easier, with respect to the previouslydescribed procedure to monitor the SO2 flux of a specificvolcano such as Mt. Etna.