Hotstuff seminar - Sara Osman - University of Bristol. Title: Impact of particle size distribution (PSD) on modelled ash dispersion, and recommendations for selecting an appropriate PSD

13 September 2019, 1.00 PM - 13 September 2019, 2.00 PM

Sara Osman, University of Bristol

Room G8, School of Earth Sciences, Wills Memorial Building

We are pleased to welcome Sara Osman from University of Bristol, who will be delivering this week's Hotstuff seminar:-

Title: Impact of particle size distribution (PSD) on modelled ash dispersion, and recommendations for selecting an appropriate PSD

Abstract: 

The size distribution of particles making up a volcanic ash cloud can vary significantly with eruption and this affects both the extent of the cloud and ash concentrations, because sedimentation rates are controlled by particle size. It is therefore very important to initialise dispersion models with an appropriate PSD for the eruption being simulated. I compiled published grain size data for a wide range of eruptions and used the NAME dispersion model to test the sensitivity of modelled ash concentrations to the input PSD. I found clear differences between modelled mass loadings and the extent of the plume for mafic and silicic eruptions. The default PSD used by the London Volcanic Ash Advisory Centre when providing forecasts to civil aviation is most similar to the finest (silicic) test eruptions and I recommend that a second default PSD should be considered for operational forecasting, suitable for coarse-grained, mafic eruptions.

All staff and students welcome. 

Contact information

For further information, please contact Damaris Butters.

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