Dr. Mark Woodhouse (Postdoctoral Research Assistant, School of Mathematics, University of Bristol)
Explosive volcanic eruptions, such as eruptions of Eyjafjallajökull 2010, Grimsvötn 2011 and Puyehue Cordón-Caulle 2011, inject huge quantities of ash high into the atmosphere that can be spread over large distances. The 2010 eruption of Eyjafjallajökull, Iceland, demonstrated the vulnerability of European and transatlantic airspace to volcanic ash in the atmosphere. Airspace management during eruptions relies on forecasting the spreading of ash.
A crucial requirement for forecasting ash dispersal is the rate at which material is delivered from the volcano to the atmosphere, a quantity known as the source mass flux. It is currently not possible to measure the source mass flux directly, so an estimate is made by exploiting a relationship between the source mass flux and the height of the plume which is obtained from the fundamental dynamics of buoyant plumes and calibrated using a dataset of historical eruptions. However, meteorology is not included in the calibrated scaling relationship. Our recent study, published in the Journal of Geophysical Research, shows that meteorology, in particular wind conditions, at the time of the eruption has large effect on the rise of the plume. Neglecting the wind can lead to under predictions of the source mass flux by more than a factor of 10.
Our model, PlumeRise, allows detailed meteorological data to be included in the calculation of the plume dynamics. By applying PlumeRise to the record of plume height observations during the Eyjafjallajökull eruption we reconstruct the behavior of the volcano during April 2010, when the disruption to air traffic was greatest. Our results show the source mass flux at Eyjafjallajökull was up to 30 times higher than estimated using the calibrated scaling relationship.
Underestimates of the source mass flux by such a large amount could lead to unreliable forecasts of ash distribution. This could have extremely serious consequences for the ash hazard to aviation. In order to allow our model to be used during future eruptions, we have developed the PlumeRise web-tool.
PlumeRise (www.plumerise.bris.ac.uk) is a free-to-use tool that performs calculations using our model of volcanic plumes. Users can input meteorological observations, or use idealized atmospheric profiles. Volcanic source conditions can be specified and the resulting plume height determined, or an inversion calculation can be performed where the source conditions are varied to match the plume height to an observation. Multiple runs can be performed to allow comparison of different parameter sets.
The PlumeRise model was developed at the University of Bristol by Mark Woodhouse, Andrew Hogg, Jeremy Phillips and Steve Sparks. The PlumeRise web-tool was developed by Chris Johnson (University of Bristol). The tool has been tested by several of the Volcanic Ash Advisory Centres (VAACs). It is also being used by academic institutions around the world. Our research is part of the VANAHEIM project. The development of the PlumeRise web-tool was supported by the University of Bristol’s Enterprise and Development Fund.