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

Journal of Geophysical Research

By:
, ,
DOI: 10.1029/2011JB008968

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Abstract

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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Ash3d: A finite-volume, conservative numerical model for ash transport and tephra deposition
Series title:
Journal of Geophysical Research
DOI:
10.1029/2011JB008968
Volume
117
Year Published:
2012
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
Volcano Science Center
Description:
20 p.; B04204
Larger Work Type:
Article
Larger Work Subtype:
Journal Article