Multiscale Modeling of Convection and Pollutant Transport Associated with Volcanic Eruption and Lava Flow: Application to the April 2007 Eruption of the Piton de la Fournaise (Reunion Island)

Abstract

Volcanic eruptions can cause damage to land and people living nearby, generate high concentrations of toxic gases, and also create large plumes that limit observations and the performance of forecasting models that rely on these observations. This study investigates the use of micro- to meso-scale simulation to represent and predict the convection, transport, and deposit of volcanic pollutants. The case under study is the 2007 eruption of the Piton de la Fournaise, simulated using a high-resolution, coupled lava/atmospheric approach (derived from wildfire/atmosphere coupled code) to account for the strong, localized heat and gaseous fluxes occurring near the vent, over the lava flow, and at the lava–sea interface. Higher resolution requires fluxes over the lava flow to be explicitly simulated to account for the induced convection over the flow, local mixing, and dilution. Comparisons with air quality values at local stations show that the simulation is in good agreement with observations in terms of sulfur concentration and dynamics, and performs better than lower resolution simulation with parameterized surface fluxes. In particular, the explicit representation of the thermal flows associated with lava allows the associated thermal breezes to be represented. This local modification of the wind flow strongly impacts the organization of the volcanic convection (injection height) and the regional transport of the sulfur dioxide emitted at the vent. These results show that explicitly solving volcanic activity/atmosphere complex interactions provides realistic forecasts of induced pollution.

VogCast: A Framework for Modeling Volcanic Air Pollution and Its Application to the 2022 Eruption of Mauna Loa Volcano, Hawai'i

“…Second, given the uncoupled nature of the VogCast system, the dynamical feedbacks between the volcanic updrafts and the ambient atmosphere are not modeled. Intense surface heating associated with high‐impact events such as eruptions and wildfires often modifies the local wind field (Filippi et al., 2021). This, in turn, can impact both the horizontal and the vertical motion of the dispersing plume.…”

“…Hawai'i’s steep terrain requires horizontal model grid spacing on O(1 km) in order to reasonably capture wind and turbulence fields (Cherubini et al., 2008), often crossing the ”gray zone” between meso‐ and micro‐scale regimes (Chow et al., 2019). While multi‐scale WRF simulations are gaining increasing attention (Filippi et al., 2021; Wang et al., 2022; Wiersema et al., 2020), their computational cost remains prohibitive for operational implementation. Moreover, the spatiotemporal resolution of meteorological fields also plays a key role in subsequent dispersion modeling, often dictating the choice of a vertical motion method applied to the simulation.…”

Volcanic air pollution and human health: recent advances and future directions

“…Further improvement of meteorological and dispersion models can help calculate ground-based pollutant concentrations at higher spatial and temporal resolution. Refining input parameters, plume models, and dynamic boundary layer representation, or incorporating advanced mathematical models such as Large Eddy Simulation, may also lead to much improved modeled concentrations (Barsotti et al 2020;Burton et al 2020, Holland et al 2020Filippi et al 2021). Limitations in the accuracy and speciation of ground-level concentrations from models or space-based instruments will require the continuation of ground-based in situ measurements.…”