Report on the IAVCEI-WMO workshop on Ash Dispersal Forecast and Civil Aviation

The regulatory response to the 14 April 2010 Eyjafjallajökull eruption (Iceland) resulted in severe disruption to air traffic. By 21 April, the UK Civil Aviation Authority (CAA) and Eurocontrol had pioneered a new way to manage the crisis based on ash concentration thresholds defined by engine manufacturers. Both the initial zero ash tolerance approach by ICAO and the new ash concentration thresholds, used by the UK MetOffice and currently under discussion within ICAO, require robust ash dispersal forecasting based on the combination of Numerical Weather Prediction (NWP), Volcanic Ash Transport and Dispersal Models (VATDM) and ash cloud data acquisition.