Modelling SO₂ conversion into sulfates in the mid-troposphere with a 3D chemistry transport model: the case of Mount Etna's eruption on 12 April 2012

Abstract. Volcanic activity is an important source of atmospheric sulfur dioxide (SO2), which, after conversion into sulfuric acid, induces impacts on rain acidity, human health, meteorology and the radiative balance atmosphere, among others. This work focuses SO2 sulfates (SO4(p)2-, S(+VI)) in mid-tropospheric volcanic plume emitted by explosive eruption Mount Etna (Italy) 12 April 2012, using CHIMERE chemistry transport model. As location composition depend several often poorly constrained parameters, a model allows us to study sensitivity oxidation multiple aspects, such as water emissions, transition metal diffusion altitude. Our results show that two pathways contribute sulfate production mid-troposphere: (1) OH gaseous phase (70 %) (2) aqueous O2 catalysed Mn2+ Fe3+ ions (25 %). Oxidation faster process, but liquid scarce mid-troposphere; therefore, relative share can be important. After 1 d mid-troposphere, about 0.5 % was converted via process. Because nonlinear dependency kinetics amount availability metals phase, experiments have been designed determine prominence different parameters. simulations that, during short time remains plume, around 0.4 manage quickly enter phase. Sensitivity tests regarding advection scheme shown this must chosen wisely, dispersion will impact both explained above.