## Concentration / Display / Particle

In addition to the normal display programs for air concentrations, which are designed to display and contour the actual values, the particle display programs only show the instantaneous positions of the pollutant particles or puffs that are integrated in time by the model to produce the air concentration fields. To generate the particle position graphics from this menu it is necessary to generate a particle dump file (default name: PARDUMP), which may contain one or more time periods of output. The creation of this file is controlled by the parameters set in the menu tab: "Advanced / Configuration Setup / Concentration."

The particle display menu requires the name of the particle position input file, the base name of the Postscript output file, the type of particle display requested, and some additional options. The mass sizing changes the size of the particle display dot according to its mass, the color scale option sets the dot color according to the height of the particle, and the GIS option (valid only for the horizontal plot) outputs either the ESRI generate format file or a Google Earth KML file. The Set Cross button permits the specification of the actual cross-section vector, rather than letting the program determine it automatically. Note that similar to the trajectory and concentration plotting programs, shapefiles can also be defined for the map background.

The "Horizontal" option results in the conventional graphic shown below. There is one black dot for each particle. The size of the dot varies according to the pollutant mass assigned to the particle. All examples are 24 hours after the start of the test simulation.

The "vertical" option shows an integrated particle distribution view from the south looking north (top panel) and from the east looking west (bottom panel). All particles in the computational domain are shown.

The "cross-section" view is a combination of the horizontal and vertical views. The top panel shows the horizontal particle distribution, while the bottom panel shows the vertical distribution along the red regression line through the plume. Again all particles are shown regardless of their distance from the regression line. The bottom panel view is from left to right in increasing longitude, regardless of the orientation of the regression line.

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