The impact of ensemble meteorology on volcano emission estimates and ash dispersion forecasts

In the event of a volcanic eruption airlines need to make fast decisions about which routes are safe to operate and to ensure airborne aircraft land safely.  Currently these high-impact decisions are based on qualitative forecasts produced without any indication of uncertainty. Two of the largest sources of uncertainty in forecasting ash cloud location and concentration are the emissions of ash from the volcano and the meteorological situation. This study extends the UK Met Office Inversion Technique for Emission Modelling (InTEM) system to use an ensemble of meteorological conditions to investigate the dependence of emission estimates on wind field and wet deposition uncertainty. In the case of the 2011 Grimsvotn eruption, preliminary work shows that the impact of the variability of the ensemble wind fields is greater than that of the variability in the wet deposition. The next steps in this research are to quantify the improvement in the forecasts of ash location due to this ensemble approach and to develop an operational methodology that can be applied in a real-time emergency response situation.