Volcanic plumes detection and retrievals from remote sensing systems: recent development and future improvements

Explosive eruptions produce high amount of volcanic particles (tephra) and gases (mainly H2O, CO2 and SO2) that are dispersed in the atmosphere forming volcanic clouds. Tephra particles have highly variable sizes (from microns to decimetres), very irregular shapes and variable compositions. The dispersal and the fallout of tephra are one of the most important volcanic causes of health problems, damage of critical infrastructures and aviation disruptions. In order to mitigate the effects of volcanic plumes on environment and society, a reliable discrimination and retrievals of volcanic plumes characteristics are needed. During the last years, remote sensing techniques have increased their capability to analyse the volcanic activity. The development of new sensors and the improvement of new algorithms, many of them satellite-based (Corradini et al., 2018), have in fact increased our capability to give reliable assessments in near real time (Scollo et al., 2019). Different sensors, spanning from microwave (MW) to thermal infrared (TIR) wavelengths, are sometimes integrated to capture the wide range of class-sizes within the volcanic plumes. In this work we show how TIR radiometric data, in some cases used in conjunction with MW and millimetre-wave (MMW) measurements, can give a complete characterization of volcanic plumes. Here we will show some applications to the Calbuco (Chile) 2015 eruption and the recent Etna (Italy) explosive activity, characterized by more than 60 powerful lava fountains in less than 2 years (Figure 1, left). To assure reliable and accurate results, a products validation is needed. Here, the results obtained for Etna are compared with data coming from several ground-based instruments installed around the volcano (Figure 1, right).