It combines the best features of grid-based Eulerian dispersion methodologies with Lagrangian particle dispersion modeling.
Species can include gases, and a spectrum of aerosol sizes.
The advantage is greatest near a source region for tracers when the source is small and unresolvable on the Eulerian grid. A comparable Eulerian treatment would necessarily represent the source by a volume no smaller than one grid cell, and would immediately begin diffusing the tracer in adjacent cells. A Lagrangian approach, on the other hand, is fully capable of representing a source of any size, and of maintaining a concentrated, narrow plume downwind of the source until atmospheric dispersion dictates that it should broaden. In contrast, at large distances from the source, where the tracer plume is typically broad and well mixed, representation of the plume by Lagrangian particles can become inefficient due to the large number of particles required to achieve a smooth characterization of the plume. Source geometry can include point, line area and volume sources of various orientations.