A model run is the date and time associated to when an instance of the NAME model is started. London VAAC volcanic ash forecasts are generated by our team of forecasters using an atmospheric transport and dispersion model called NAME. The model represents the expected behaviour of the volcanic ash cloud, the direction and speed of travel as well as processes which act to remove ash from the atmosphere: through precipitation, sedimentation (falling out through gravity) and interaction with the Earth’s surface.
After the initial model run is used to produce the very first volcanic ash forecasts following a significant volcanic event, our forecasting team will update the forecasts every 6 hours, up until the time ash is no longer discernible.