2011–2015 Etna lava fountains BrO Bárðarbunga Differential Absorption Lidar (DIAL) Etna volcano Holuhraun Mount Etna O3 Python 2.7 Q1-390 SEVIRI data SO2 SSA Taylor bubble UV cameras aerosol optical properties analysis software atmospheric chemistry atmospheric remote sensing basaltic volcanism bic Book Industry Communication::G Reference, information & interdisciplinary subjects::GP Research & information: general cloud height degassing processes eruption monitoring eruption start and duration fissure eruption gas gas slug gases geochemical modelling