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

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

2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June The basic model.. from ‘How volcanoes work’ site, Dr Vic Camp,

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

2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June Pinatubo GMS brightness temperature, 17 June – 30 Sept 1991 (Tupper, Oswalt, Rosenfeld, under preparation)

2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June Diurnal variation (Tupper, Oswalt, Rosenfeld, under preparation) Enchanced, altered diurnal cycle

2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June Detecting ash in convection Rosenfeld & Tupper (in review) 14 June 1991, 23Z

2nd International Conference on Volcanic Ash and Aviation Safety, Washington DC, June Effect of moisture on aggregation

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

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