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Observations of Volcanic Clouds in Their First Few Days of Atmospheric Residence: The 1992 Eruptions of Crater Peak, Mount Spurr Volcano, Alaska

TLDR
Satellite SO2 and ash measurements of Mount Spurr's three 1992 volcanic clouds are compared with ground-based observations to develop an understanding of the physical and chemical evolution of volcanic clouds as mentioned in this paper.
Abstract
Satellite SO2 and ash measurements of Mount Spurr’s three 1992 volcanic clouds are compared with ground‐based observations to develop an understanding of the physical and chemical evolution of volcanic clouds. Each of the three eruptions with ratings of volcanic explosivity index three reached the lower stratosphere (14 km asl), but the clouds were mainly dispersed at the tropopause by moderate to strong (20–40 m/s) tropospheric winds. Three stages of cloud evolution were identified. First, heavy fallout of large (>500 μm) pyroclasts occurred close to the volcano (<25 km from the vent) during and immediately after the eruptions, and the cloud resembled an advected gravity current. Second, a much larger, highly elongated region marked by a secondary‐mass maximum occurred 150–350 km downwind in at least two of the three events. This was the result of aggregate fallout of a bimodal size distribution including fine (<25 μm) ash that quickly depleted the solid fraction of the volcanic cloud. For the f...

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Multi-decadal satellite measurements of global volcanic degassing

TL;DR: In this article, the authors examined the temporal and latitudinal distribution of volcanic SO 2 emissions and reassess the relationship between eruptive SO 2 discharge and eruption magnitude, finding a first-order correlation between SO 2 emission and volcanic explosivity index (VEI), but with significant scatter.
Journal ArticleDOI

A review of volcanic ash aggregation

TL;DR: In this paper, the authors used remote sensing studies of volcanic 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.
Journal ArticleDOI

A three-dimensional Eulerian model for transport and deposition of volcanic ashes

TL;DR: In this paper, an Eulerian model, named FALL3D, was developed for the transport and deposition of volcanic ashes based on the advection-diffusion-sedimentation equation with a turbulent diffusion given by the gradient transport theory.
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Sedimentation from strong volcanic plumes

TL;DR: In this paper, the authors developed descriptions of the key processes influencing tephra dispersal from strong volcanic plumes, characterized by the development of a subvertical eruption column in the atmosphere that forms a spreading current at a level of neutral buoyancy.
Journal ArticleDOI

Quantitative shape measurements of distal volcanic ash

TL;DR: In this paper, a methodology was developed to characterize particle shapes, sizes, and terminal velocities for three volcanic ash samples of different compositions, including distal fallout from the 14 October 1974 Fuego eruption (basaltic), secondary maxima (∼250 km) of the 18 August 1992 Spurr eruption (andesitic), and the Miocene Ash Hollow member, Nebraska (rhyolitic).
References
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Journal ArticleDOI

The thickness, volume and grainsize of tephra fall deposits

TL;DR: In this paper, an improved empirical method for the plotting of field data and the calculation of tephra fall volumes is presented, where two new quantitative parameters are proposed which describe the rates of thinning of the deposit (bt the thickness half distance) and the maximum clast size (bc the clast half distance).
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Retrieval of sizes and total masses of particles in volcanic clouds using AVHRR bands 4 and 5

TL;DR: In this paper, the authors used a semi-transparent cloud model that is based on assumptions of spherical particle shape, a homogeneous underlying surface, and a simple thin cloud parallel to the surface, applied to observed AVHRR data from a 13-hour old drifting cloud from the August 19, 1992, eruption of Crater Peak/Spurr Volcano, Alaska.
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Influence of particle aggregation on deposition of distal tephra from the MAy 18, 1980, eruption of Mount St. Helens volcano

TL;DR: In this paper, a computer simulation of ash fallout from an atmospherically dispersed eruption plume was developed to evaluate various hypotheses for the origin of the distal ash characteristics, particularly the thickness versus distance relationship.
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Self-limiting physical and chemical effects in volcanic eruption clouds

TL;DR: One-dimensional aerosol microphysical and photochemical models are used to study the chemistry of stratospheric volcanic clouds as discussed by the authors, and the results indicate that the microphysical processes of condensation and coagulation produce larger particles as the SO2 injection rate is increased, suggesting that volcanic effects may be self limiting.
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Thickness variations and volume estimates of tephra fall deposits: the importance of particle Reynolds number

TL;DR: In this article, it was shown that major changes in thinning rate occur as the particle size decreases with distance from the vent, as a consequence of the change of settling behavior from high to low Reynolds number as predicted by W.I. Rose.
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