Applying the three-dimensional model ATHAM to volcanic plumes: Dynamic of large co-ignimbrite eruptions and associated injection heights for volcanic gases

Abstract

Many of the past large volcanic eruptions like Tambora in 1815, Krakatau in 1835, and Pinatubo in 1991 were secondary so called co-ignimbrite eruptions that were forced over a large area instead of a point source as in the Plinian case. Previous modeling studies were based on one-dimensional plume models. We used the fully three-dimensional plume model ATHAM (Active Tracer High-Resolution Atmospheric Model) to investigate the dynamics and the resulting plume heights of co-ignimbrite eruptions in an idealized setup. Ash particles as well as a sulfur dioxide (SO 2) tracer are included in the model. In the analysis we focus on the behavior of SO 2 since the neutral buoyancy height is an ill-defined parameter for gravitationally settling particles. In contrast to Plinian plumes the co-ignimbrite plumes develop from multiple updrafts resulting in significantly reduced neutral buoyancy heights. At least a two-dimensional modeling framework is necessary to capture the relevant dynamical features. © 2010 by the American Geophysical Union.