Source Attribution via Source-Receptor Matrices

The matrix approach to source attribution is set up in a similar manner to the previous discussion but run with multiple sources.  Use three similar, although shifted northwest, starting locations as with the dust storm simulation to define the source region (20N-40N and 25W-0W). Using the FNLDUST data, run (500) 3D-particles for 96 hours with concentration output at 100 m every 6 hours (remember to set the output level back to 100 meters if you still have it set at 0 m from the deposition case and to turn off deposition), set the maximum number of particles to at least 125000, and set the Grid Center lat/lon to 30N,10W. Reduce the resolution of the concentration grid to 0.75 to reduce the memory requirements.  Prior to executing the model through the Run Matrix tab of the Concentration / Special Simulations menu, it is necessary to check the Restructure the concentration grid to the source-receptor format button in the Advanced / Configuration Setup / Concentration / In-line chemical conversion modules menu.  This causes the concentration grid to be reconfigured so that every source location within the matrix (546 in this example) will have its own concentration grid. This run will take a few minutes to complete.

The final concentration output file can only be displayed through the Matrix tab of the Display Options menu.  The term “matrix” has two connotations with respect to HYSPLIT. In the earlier application, a matrix of sources was created.  These results are summed to a single concentration file.  In this application, defining a concentration grid for each source creates a matrix of sources and receptors.  This requires a special preprocessor for the display program.  In this example, selecting the receptor button causes the entered latitude-longitude value to be treated as the receptor point.  The dispersion factors from each source to that receptor are then interpolated to a grid and displayed by time period.  The last time period (0000 UTC, February 27), coincident with the TOMS image, is shown below.