Context and Objectives
The Etna volcano in Sicily (Italy) is a massive SO2 emitter. The emitted SO2 can be oxidized in the atmosphere, forming sulfate aerosols which affect the microphysical and radiative processes in the atmosphere. Understanding and modeling these processes is one objective of ANR DICIT project, coordinated by Pasquale Sellitto (LISA).

The objective of this internship i­s to study a rapid sulfate formation event observed in July 2016 (Sellitto et al., 2020) for which photometric and LIDAR observations of the freshly formed sulfate plume downwind of the Etna crater are available. For this purpose, the student will analyze simulations performed with the CHIMERE model (https://www.lmd.polytechnique.fr/chimere). While other cases of SO2 oxidation have been modeled in the past with CHIMERE (Lachatre et al., 2022), the case proposed for this internship is very different, since it concerns SO2 emitted by passive (non-explosive) degassing, for which kilometric-resolution simulations around the crater will be needed.

The student will analyze kilometer-scale simulations performed with the CHIMERE model and compare them with the observations in terms of aerosol optical depth and LIDAR observables. This work will assess CHIMERE’s ability to reproduce the rapid conversion of SO₂ into sulfate aerosols in a fresh plume produced by passive volcanic degassing. Depending on progress, sensitivity simulations may also be conducted to investigate the processes controlling sulfate formation.

Organisation
The internship will be co-tutored by Guillaume Siour (LISA) and Sylvain Mailler (LMD), in collaboration with Pasquale Sellitto (LISA). It will mainly take place at LMD (École Polytechnique, Palaiseau).

References
Sellitto, P., Salerno, G., La Spina, A. et al. Small-scale volcanic aerosols variability, processes and direct radiative impact at Mount Etna during the EPL-RADIO campaigns. Sci Rep 10, 15224 (2020), https://doi.org/10.1038/s41598-020-71635-1

Lachatre, M., Mailler, S., Menut, L. et al., 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, Atmos. Chem. Phys (2022), https://doi.org/10.5194/acp-22-13861-2022