Estimation of dispersion coefficient in the troposphere from satellite images of volcanic plumes: Application to Mt. Etna, Italy

The lateral dispersion of volcanic plumes in the troposphere is investigated using satellite images. Two plume images have been selected from the Mount Etna eruption that occurred in October/November 2002.To reproduce the satellite images two modelling approaches are presented. The first one uses deterministic trajectories released from a line source extending over a range of altitudes chosen from direct observations. The second uses stochastic trajectories from an area source located at a fixed height, where the source size and the effective diffusion coefficient are determined by data analysis. The meteorological model BOLAM (Bologna Limited Area Model) supplies the atmospheric dynamics. Both approaches reproduce the main features of the observed plumes, with differences in the cross section distribution of the density.