  The main aim of the present work is to improve the quality of the Etna
volcanic ash fallout forecasts through the optimization of an integrated
simulation system based on the Weather Research and Forecasting (WRF) model
coupled with the WRF chemistry (WRF - Chem) module. The proposed approach
constitutes the first systematic application of the WRF - Chem based protocol
to a specific Etna volcanic eruption, with possible effects involving the whole
Mediterranean area. On that score, the attention has been focused on the
eruption event, recorded on December 2015 from 3$^rd$ to 7$^th$, which led to
the closure of the Catania International Airport. Quantitative meteorological
forecasts, analyses of the Etna volcanic ash transport and estimates of the ash
ground deposition have been performed. In order to test the performance of the
employed approach, the model outputs have been compared with data provided by
satellite sensors, Doppler radars and weather stations. As a result, it emerges
that, as far as the selected eruption event is concerned, the WRF-Chem model
correctly reproduces the distribution of SO$_2$ and of volcanic ash. Therefore,
this model may provide a valuable support both to airport managements and to
local stakeholders including public administrations.
