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

Textor, C.; Graf, Hans‐F.; Herzog, Michael; Oberhuber, Josef M.; Rose, William I.; Ernst, Gérald

doi:10.1016/j.jvolgeores.2005.09.007

Cited by 92 publications

(111 citation statements)

References 91 publications

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“…Poorly-understood factors such as wind (Bursik et al, this volume), particle fallout (Woods and Bursik, 1991), vent overpressure (Ogden et al, 2008), or development of hydrometeors (Durant et al, in review;Textor et al, 2006), along with atmospheric humidity for larger eruptions (Tupper et al, in press) may all influence this relationship. Finally, as illustrated by Barsotti and Neri (2008) at Etna, some scatter may reflect temporal variations in plume height or eruption rate that are not accurately reflected in the average values in Table 1.…”

Section: Plume Height Versus Eruption Ratementioning

confidence: 99%

A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

Mastin

Guffanti

Servranckx³

et al. 2009

Journal of Volcanology and Geothermal Research

619

766

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Section: Plume Height Versus Eruption Ratementioning

confidence: 99%

A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

Mastin

Guffanti

Servranckx³

et al. 2009

Journal of Volcanology and Geothermal Research

619

766

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“…The availability and abundance of water in the eruption cloud exerts a dominant control on aggregation (Gilbert and Lane, 1994;Veitch and Woods, 2001;Costa et al, 2010;Folch et al, 2010;Textor et al, 2006a and b). Initial fragmentation, particle collisions, mixed phase clouds and particle separation all lead to particle charging (Mather and Harrison, 2006) which influences particle collisions and may provide binding forces in the absence of water (more relevant for clouds 1000s km from source or >24 hours in age).…”

Section: Aggregation Within Ash Plumes: Conditions and Downwind Changesmentioning

confidence: 99%

“…Particle aggregation is a complex time-dependent process and is better described by a numerical solution. However, numerical models only exist for wet aggregation (Veitch and Woods, 2001;Textor et al, 2006a,b: Costa et al, 2010Folch et al, 2010) and wet sedimentation (i.e., removal of ash due to rain; Stohl et al, 2005;Draxler and Hess, 1998;D'Amours et al, 2010;Jones et al, 2007;. Here we will only describe details of wet-aggregation modelling.…”

Section: Empirical and Numerical Studies On Aggregationmentioning

confidence: 99%

“…While aggregation exerts a first order control on the dispersal of fine ash within eruption clouds, the physical and chemical processes involved are not completely understood despite significant progress over the past twenty years (Schumacher and Schmincke, 1995;Gilbert and Lane, 1994;James et al, 2002James et al, , 2003Textor et al, 2006a and b;Costa et al, 2010). Fine airborne particles adhere to each other as a result of electrostatic attraction, moist adhesion between particles (e.g., Sorem, 1982;Gilbert and Lane, 1994;Schumacher andSchmincke, 1991, 1995;James et al, 2002) and hydrometeor formation (e.g., Veitch and Woods, 2001;Textor et al, 2006a;. The atmospheric residence time of fine ash determines the hazard to aviation (Casadevall, 1994), and ash fallout impacts local environments and infrastructure (Stewart et al, 2006;Spence et al, 2005;Wardman et al, 2011) and may present a health hazard over an extended period of exposure (Horwell and Baxter, 2006).…”

Section: Introductionmentioning

confidence: 99%

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A review of volcanic ash aggregation

Brown

Bonadonna

Durant

2012

Physics and Chemistry of the Earth, Parts A/B/C

227

298

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. (2012) 'A review of volcanic ash aggregation.', Physics and chemistry of the earth, parts A/B/C., 45-46 . pp. 65-78. Further information on publisher's website:http://dx.doi.org/10.1016/j.pce. 2011.11.001 Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractMost volcanic ash particles with diameters < 63 µm settle from eruption clouds as particle aggregates that cumulatively have larger sizes, lower densities, and higher terminal fall velocities than individual constituent particles. Particle aggregation reduces the atmospheric residence time of fine ash, which results in a proportional increase in fine ash fallout within 10s km to 100s km from the volcano and a reduction in airborne fine ash mass concentrations 1000s km from the volcano. Aggregate characteristics vary with distance from the volcano: proximal aggregates are typically larger (up to cm size) with concentric structures, while distal aggregates are typically smaller (sub-millimetre size). Particles comprising ash aggregates are bound through hydro-bonds (liquid and ice water) and electrostatic forces, and the rate of particle aggregation correlates with cloud liquid water availability. Eruption source parameters (including initial particle size distribution, erupted mass, eruption column height, cloud water content and temperature) and the eruption plume temperature lapse rate, coupled with the environmental parameters, determines the type and spatiotemporal distribution of aggregates. Field studies, lab experiments and modelling investigations have already provided important insights on the process of particle aggregation. However, new integrated observations that combine remote sensing studies of 2 ash clouds with field measurement and sampling, and lab experiments are required to fill current gaps in knowledge surrounding the theory of ash aggregate formation. Abstract word count: 222

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“…Aggregation, which produces particle clusters with higher fall velocities than individual grains, is one process that can enhance the settling rate of sub-millimetre scale tephra (Brown et al 2012). Aggregation has been widely used to explain the regions of tephra fall deposits that depart from an attenuation of thickness and grain-size with distance from source (Sorem 1982;Textor et al 2006;), even when aggregated clasts have not been directly observed in the deposits (cf. Carazzo and Jellinek 2013).…”

Section: Introductionmentioning

confidence: 99%

An example of enhanced tephra deposition driven by topographically induced atmospheric turbulence

et al. 2015

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Spatial variations in the thickness and grain-size characteristics of tephra fall deposits imply that tephra depositional processes cannot be fully captured by models of single-particle sedimentation from the base of the eruption plume. Here, we document a secondary thickness maximum in a ∼9.75 ka tephra fall deposit from Chaitén volcano, Chile (Cha1 eruption). This secondary thickness maximum is notably coarser-grained than documented historical examples, being dominated by medium-grained ash, and an origin via particle aggregation is therefore unlikely. In the region of secondary thickening, we propose that high levels of atmospheric turbulence accelerated particles held within the mid-to lower-troposphere (0 to ∼6 km) towards the ground surface. We suggest that this enhancement in vertical atmospheric mixing was driven by the breaking of lee waves, generated by winds passing over elevated topography beneath the eruption plume. Lower atmospheric circulation patterns may exert a significant control on the dispersal and deposition of tephra from eruption plumes across all spatial scales, particularly in areas of complex topography.

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

Cited by 92 publications

References 91 publications

A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

A review of volcanic ash aggregation

An example of enhanced tephra deposition driven by topographically induced atmospheric turbulence

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