Numerical simulation of explosive volcanic eruptions from the conduit flow to global atmospheric scales

Abstract

Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth's climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft -ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.

Online treatment of eruption dynamics improves the volcanic ash and SO<sub>2</sub> dispersion forecast: case of the 2019 Raikoke eruption

“…However, in all parametrizations of the ESPs the volcanic plume dispersion remains decoupled from unresolved volcanic eruption dynamics including also the influence of the atmosphere on the emission height. This accounts for large uncertainties in modeling studies at regional to global scales (Textor et al, 2005;Timmreck, 2012;von Savigny et al, 2020). Marti et al (2017) overcame this issue by coupling the NMMB-MONARCH-ASH transport model (Nonhydrostatic Multiscale Model on the B grid-Multiscale Online Nonhydrostatic AtmospheRe CHemistry model-ash) with the 1D plume model FPlume, which calculates the MER and the mass distribution in the column online.…”

Interactive simulation of plume and pyroclastic volcanic ejections

“…As volcanic plumes can rise over tens of kilometers before reaching their equilibrium altitude, coarse spatial resolutions are used, with voxels typically spanning a hundred meters. Therefore, only large-scale phenomena such as the plume expansion as well as macroscopic chemical and thermodynamic exchanges are captured [26,29], while smaller scale phenomena are only averaged. Spatial resolution is too coarse to reproduce the visual appearance observed on pictures of real volcanic ejections, where small vortices of about a meter wide can be distinguished.…”

Bayesian functional emulation of CO2 emissions on future climate change scenarios

“…IAMs are generally designed to simulate the multidisciplinary aspect of a problem by combining various inputs from different fields. Large scale computer simulations of this nature are widely utilized in modern scientific research to study physical phenomena that are either too costly or impossible to replicate directly (Fan et al, 2009; Textor et al, 2005). These simulations are used to quantify how uncertainty in the input variables affects the output and how much uncertainty is introduced through the modeling process.…”