First Volcanic Plume Measurements by an Elastic/Raman Lidar Close to the Etna Summit Craters

Antonella Boselli,Xuan Wang,Nicola Spinelli,Simona Scollo,Alessia Sannino,Giuseppe Leto,Mauro Coltelli,Ricardo Zanmar Sanchez

doi:10.3389/feart.2018.00125

Abstract

From 14 to 17 December 2013, Mt. Etna, in Italy, showed an intense Strombolian activity from the New South East Crater (NSEC). Lidar measurements were performed in Catania, pointing at a thin volcanic plume, clearly visible and dispersed from the summit craters toward the South East. Real-time Lidar observations captured the complex dynamics of the volcanic plume along with the pulsatory nature of the explosive activity and allowed to analyze the geometrical, optical and microphysical properties of the volcanic ash. Both the aerosol backscattering (βA) and the extinction coefficient (αA) profiles at 355nm, and their ratio (the Lidar Ratio - LR) were measured near the volcanic source using an Elastic/Raman Lidar system. Moreover, calibrated particle linear depolarization values (δA) were obtained from the Lidar profiles measured in the parallel and cross polarized channels at 355nm, thus allowing to characterize the particle shape. The βA, LR and δA values were used to estimate the ash concentration (γ) profiles in the volcanic plume. This is the first study of optical properties of volcanic particles through Elastic/Raman measurements at Etna volcano.

Highlights

The amount and composition of silicate particles and gasses emitted during volcanic eruptions are the result of very complex processes (Robock and Oppenheimer, 2003) which depend on different variables, such as chemistry of magma and mechanisms of its ejection and removals
We present the results of Elastic/Raman Lidar measurements carried out during the 16 December, 2013 Etna explosive activity and we show the measurements of volcanic plume optical parameters detected near the summit craters
Etna eruptions are mainly produced from the summit craters (e.g., Alparone et al, 2003; Behncke et al, 2006; Scollo et al, 2013) and from some fractures opened on the volcano flanks (e.g., Rittmann, 1973; Branca and Del Carlo, 2005)

Summary

Introduction

The amount and composition of silicate particles and gasses emitted during volcanic eruptions are the result of very complex processes (Robock and Oppenheimer, 2003) which depend on different variables, such as chemistry of magma and mechanisms of its ejection and removals. The knowledge of the atmospheric particles content may be very useful to define the eruption style and discriminate sulfate and/or water vapor dominated plumes that is very important to understand their atmospheric contribution, having the erupted particles many implications in climate and environmental effects (Scollo et al, 2012a,b). In this respect, remote sensing instruments can improve the monitoring capability of volcanic ash dispersion and fallout, helping the data interpretation and optimization for a realtime alert and rapid warning dissemination (Ripepe et al, 2013; Corradini et al, 2016). Results of real time observations are useful to improve volcanic ash forecasts (Scollo et al, 2015)

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