The Lagrangian particle dispersion model FLEXPART in its original version in the mid-
1990s was designed for calculating the long-range and mesoscale dispersion of hazardous
substances from point sources, such as those released after an accident in a nuclear power
plant. Over the past decades, the model has evolved into a comprehensive tool for multi-
scale atmospheric transport modeling and analysis and has attracted a global user
community. Its application fields have been extended to a large range of atmospheric gases …