The first phase of VolPlume focused on the chemical and microphysical evolution of the eruption plume in two separate work packages. In the second phase, we will combine these developments (multiphase version of  ICON-ART, aerosol dynamics and gas phase chemistry) in one modeling suite to investigate the collective impacts of these processes on the chemical and microphysical evolution of volcanic plumes at LES scales in the first few hours of the eruption.

Shape, size distribution, and composition of the ash particles play key roles in the atmospheric life-time and impacts of volcanic ash. These parameters are studied separately but not yet integrated in one modeling suit. To close this gap, we will build on the advancements made with respect to plume modeling, aerosol dynamics, and aerosol-radiation interactions in phase I and improve the understanding of the volcanic ash role in chemical, microphysical and optical evolution of the eruption plume.

To validate the modeling results, we use novel satellite observations and sophisticated dynamical system analysis tools to characterize the near-field to far-field volcanic plume evolution. In particular, we will exploit GOES-16 mesoscale domain data for the 2021 La Soufrière eruption, offering an unprecedented 1-minute resolution time series for the analysis of rapid near-vent processes. We will also determine the hyperbolic Lagrangian Coherent Structures of the simulated unsteady flow; these are material lines that repel or attract particles locally the strongest and, by acting as transport barriers, guide the formation of the tendril-like far-field plume structure.

The overarching research questions are:

• How does the interplay of chemistry and microphysics affect the evolution of volcanic plumes (WP1)?  
• What is the role of ash in the initial stage of volcanic plume development (WP2)?
• What governs the near-field IR signature and the far-field transport of plumes (WP3)?

Ali Hoshyaripour (PI, KIT), Bernhard Vogel (Co-I, KIT), Akos Horvath (Co-I, University of Hamburg), Stefan Bühler (Co-I, University of Hamburg)

Horváth, Á., Carr, J. L., Wu, D. L., Bruckert, J., Hoshyaripour, G. A., and Buehler, S. A.: Measurement report: Plume heights of the April 2021 La Soufrière eruptions from GOES-17 side views and GOES-16–MODIS stereo views, Atmos. Chem. Phys. Discuss. [preprint], doi.org/10.5194/acp-2022-253, 2022.