Reply to comment by C. Textor and G. G. J. Ernst on“Particle aggregation in volcanic eruption columns”

Veitch, Graham; Woods, Andrew W.

doi:10.1029/2003jb002388

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…The settling velocity of nonspherical particles is also allowed to vary as a function of height above the ground due to major variations in air density and viscosity with altitude [ Wilson , 1972]. In contrast, particle aggregation processes are not described by the present model, although they can play a major role in some conditions [ Textor and Ernst , 2004; Veitch and Woods , 2004].…”

Section: The Vol‐calpuff Codementioning

confidence: 99%

“…Later on, the equation sets of these so‐called “plume theory” models were integrated by adding the energy conservation equation in different forms [ Woods , 1988; Glaze and Baloga , 1996]. Further developments concerned the modeling of thermal disequilibrium [ Woods and Bursik , 1991], particle fallout from the column [ Woods and Bursik , 1991; Ernst et al , 1996], and umbrella cloud [ Bursik et al , 1992b; Bonadonna et al , 1998], and particle recycling into the eruption column [ Ernst et al , 1996; Veitch and Woods , 2002, 2004; Textor et al , 2004]. Crosswind influence on plume tilting has also been addressed based on experimental and theoretical work on turbulent buoyant plumes in cross flow [ Hoult and Weil , 1972; Wright , 1984; Ernst et al , 1994; Bursik , 2001].…”

Section: Introductionmentioning

confidence: 99%

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The VOL‐CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

2008

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[1] We present a new modeling tool, named VOL-CALPUFF, that is able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely used in environmental applications of pollutant dispersion, that describes the dispersal process in both the proximal and distal regions and also in the presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 h. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, this paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper, Barsotti and Neri present a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) with the specific aim of comparing model predictions with independent observations.

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Section: The Vol‐calpuff Codementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The VOL‐CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

2008

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Volcanic particle aggregation in explosive eruption columns. Part I: Parameterization of the microphysics of hydrometeors and ash

Textor

Graf

Herzog

et al. 2006

Journal of Volcanology and Geothermal Research

109

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

Textor

Graf

Longo

et al. 2009

Annals of Geophysics

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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.

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Reply to comment by C. Textor and G. G. J. Ernst on“Particle aggregation in volcanic eruption columns”

Cited by 3 publications

References 11 publications

The VOL‐CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

The VOL‐CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

Volcanic particle aggregation in explosive eruption columns. Part I: Parameterization of the microphysics of hydrometeors and ash

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

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