Ash3d: A finite‐volume, conservative numerical model for ash transport and tephra deposition

Abstract

[1] We develop a transient, 3-D Eulerian model (Ash3d) to predict airborne volcanic ash concentration and tephra deposition during volcanic eruptions. This model simulates downwind advection, turbulent diffusion, and settling of ash injected into the atmosphere by a volcanic eruption column. Ash advection is calculated using time-varying pre-existing wind data and a robust, high-order, finite-volume method. Our routine is mass-conservative and uses the coordinate system of the wind data, either a Cartesian system local to the volcano or a global spherical system for the Earth. Volcanic ash is specified with an arbitrary number of grain sizes, which affects the fall velocity, distribution and duration of transport. Above the source volcano, the vertical mass distribution with elevation is calculated using a Suzuki distribution for a given plume height, eruptive volume, and eruption duration. Multiple eruptions separated in time may be included in a single simulation. We test the model using analytical solutions for transport. Comparisons of the predicted and observed ash distributions for the 18 August 1992 eruption of Mt. Spurr in Alaska demonstrate to the efficacy and efficiency of the routine.Citation: Schwaiger, H. F., R. P. Denlinger, and L. G. Mastin (2012), Ash3d: A finite-volume, conservative numerical model for ash transport and tephra deposition,

The operational eEMEP model version 10.4 for volcanic SO<sub>2</sub> and ash forecasting

“…16.25). Fine ash is shown to fall faster than the Stokes law calculates ); therefore, the more spherical shape (F = 0.8) is set as the default since slip flow corrections increase the fall speed for fine ash for more spherical fine ash particles (Schwaiger et al, 2012).…”

“…Other well-known Lagrangian models used for ash dispersion are FLEXPART (Stohl et al, 2005) and PUFF (Searcy et al, 1998); the latter is also used as backup by the Washington and Anchorage VAAC. Some Eulerian models used for ash dispersion are MOCAGE (Josse et al, 2004) used at VAAC Toulouse, Fall3d (Folch et al, 2009), and Ash3d (Schwaiger et al, 2012). The Eulerian models calculate the advection of ash at every grid point, and emissions are instantaneously mixed within the grid box.…”

The Volcanic Hazards Assessment Support System for the Online Hazard Assessment and Risk Mitigation of Quaternary Volcanoes in the World

“…Volcanic hazard assessment tools have been developed during the last few decades (e.g., Loughlin et al, 2015;Papale and Shroder, 2015). A number of deterministic offline volcanic hazard assessment tools have been developed since late 1980's, such as Energy Cone (Sheridan, 1980;Malin and Sheridan, 1982), Titan2D (Pitman et al, 2003;Sheridan et al, 2004), VolcFlow (Kelfoun and Druitt, 2005;Kelfoun et al, 2009), LaharZ (Schilling, 1998), PUFF (Searcy et al, 1998), Tephra 2 (Bonadonna et al, 2005;Connor, 2006), Hazmap (Macedonio et al, 2005), Fall3D (Costa et al, 2006;Folch et al, 2009), and Ash3d (Schwaiger et al, 2012). However, most of them require relatively complex installation procedure and usage (e.g., operation on UNIX command system and preparation of digital elevation model by themselves).…”

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

“…These flaws have been corrected in most of the recent numerical models (e.g. Macedonio et al, 2005;Costa et al, 2006;Barsotti et al, 2008;Schwaiger et al, 2012) through the integration of a particle shape factor (Wilson and Huang, 1979;Ganser, 1993;Dellino et al, 2005) accounting for the non-spherical character of volcanic ash. The result is a significant improvement in the modeling of tephra transport and dispersal, which underlines the need for reliable techniques to fully characterize the shape of volcanic ash particles.…”