2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June 2004 1

Andrew Tupper Darwin Volcanic Ash Advisory Centre, Bureau of Meteorology, Northern Territory, Australia

Gerald Ernst Geological Institute, University of Ghent, Krijgslaan, Ghent, Belgium

Christiane Textor Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France

Kisei Kinoshita Faculty of Education, Kagoshima University, Kagoshima, Japan

J.Scott Oswalt US Navy (retired), USA Daniel Rosenfeld Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel

Volcanic cloud conceptual models for

Volcanic Ash Advisory Centre operations

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Volcanic cloud data• The data we want we do not have….• This is normal in meteorological operations!• The difference with volcanic clouds is that we

haven’t had many decades of refining our theoretical and conceptual models to help us diagnose a situation.

• As a result, we can be too timid in our analysis.

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The basic model..

from ‘How volcanoes work’ site, Dr Vic Camp, http://www.geology.sdsu.edu/how_volcanoes_work/

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Volcanoes and moist convection

Graf et al (1999) Sparks et al (1997)

Eruptions in moist environments should be higher, with a larger effect for smaller eruptions… how does this look in practice? Let’s consider a volcano in an unstable troposphere.

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PinatuboGMS brightness temperature, 17 June – 30 Sept

1991

(Tupper, Oswalt, Rosenfeld, under preparation)

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Diurnal variation

(Tupper, Oswalt, Rosenfeld, under preparation)

Enchanced, altered diurnal cycle

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Detecting ash in convection

Rosenfeld & Tupper (in review)

14 June 1991, 23Z

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Effect of moisture on aggregation

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Effect of wind 3 August 1999

In the case:

Strong winds, vulcanian explosions, no observations, assume low but extended plume.

Then think: how will the wind change? Effect on airports, especially with a lee wave? Height increase when wind stops?

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The future• Basic understandings developing: the role of ice,

‘volcanic storms’, the role of volcanic processes in initiating deep convection, secondary explosions, interactions with topography etc.

• More observational & modelling work needed: intensive observation period of volcanic clouds, modelling of lower energy eruptions, more work on topography, consideration of synoptic environment…

• Will lead to standard NOTAM / SIGMET procedures for situations (eg afternoon convection above low level eruptions, secondary explosions in heavy rain).

• When is the ash removed from the atmosphere? How are we going to talk about it? Threshold concentrations, e-folding times….? Will we develop a look-up table of NOTAM / SIGMET requirements based on our diagnoses?