Using simple plume models to refine the source mass flux of volcanic eruptions according to atmospheric conditions

•3-D volcanic plume model including effects of ambient wind and moisture•Applied to realistic atmospheric profiles of wind speed, temperature and humidity•Eyjafjallajökull used as example•Results applied to long-range dispersion model

A simple three-dimensional volcanic plume model that incorporates the effects of moisture and ambient wind is presented and used iteratively to refine the source mass flux, obtained from an empirical relationship between the plume rise height and source mass flux, according to the prevailing atmospheric conditions. It is applied to the eruption of Eyjafjallajökull in May 2010 using realistic atmospheric profiles appropriate to the time of the eruption. It is shown that the ambient wind has the largest effect on the refined source mass flux with moisture playing a secondary though still important role. It is also shown that significant differences in the values of the revised source mass fluxes can arise when the realistic atmospheric profiles are approximated by idealised profiles. The revised source mass flux is used to initialise a long-range dispersion model of ash in the atmosphere.