Concentration and Particle Display Options

Set up and run a 3D, 500 particle, 6-h snapshot simulation from the initial 28.5N, 80.7W source location using a 0.01 degree resolution grid, the 12-km NAM meteorological data and set the particle dump interval to 6 hours.  The concentration output (below, top left) clearly shows a noisy pattern indicating too few particles.  Run the simulation again with 5000 particles and the results will be smoother (below, top right).  Now rerun the simulation with 50,000 particles, and the concentration pattern shows much more structure (below, bottom left).  These simulations can take quite some time, but if the model is re-run with the much quicker default scenario but using 2500 top-hat particles (500 particles is not enough in this case), the results (below, bottom right) cover similar areas as the 50,000 3D-particle simulation.

500 Particles	5,000 Particles
50,000 Particles	2500 Top-hat Particles

The Concentration / Display Options / Particle menu (right) has options to show snapshot particle distributions, assuming that the particle dump option was set in the Advanced / Configuration Setup / Concentration menu before running the particle simulation. Horizontal, vertical, and cross-sectional views are available.  Rerun the 50,000 particle simulation to produce a PARDUMP particle dump file. Then choose the particle vertical cross section and the graphic is drawn automatically based upon the particle distribution.

Another option is to view the concentration values directly on the grid without any interpolation through the Concentration / Display Options / Pointer Select tab.  This option will draw the entire concentration domain. Click on the initial map domain image with the left mouse button to display the concentrations. The span option in the initial concentration grid setup should be adjusted to optimize the view region.