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Instead of creating a single deterministic air concentration simulation, several programs are included with HYSPLIT that can be used to combine multiple HYSPLIT simulations into a single graphic that represents some variation of a concentration probability. The simplest approach is to run the model multiple times varying some parameter. In the first case the model is run with multiple meteorological data. Each simulation was from 28.5N, 80.7W at 10 m. Also, to convert these data to a probability format below, the binary output files must be named with the suffix .001, .002, etc. in the Definition of Concentration Grid 1 menu. The 6-h average concentration graphic for each meteorological data set is given below for data from the NAM 12 km, the NAM 40 km, the RUC 20 km, the AFWAMM5 15 km, the AFWAMM5 45 km, and the GFS 1 degree. Notice that the NAM and RUC results show more of an westward component than the other 3 model results.
Now before running the ensemble display program the base name of the concentration files that were just created (cdump.001 to cdump.006) must be corrected in the Definition of Concentration Grid 1 menu. Change the last one selected, in this case cdump.006 to cdump (this is automatically taken care of by the GUI if running a one meteorological dataset internal ensemble as shown below). Save the setup, but do not rerun the model. This creates a new CONTROL file with the proper base name cdump. Now select Ensemble from the Concentration / Display Options menu. Three display options are available on this menu: the Number of Members, the Probability of Concentration (probability of exceeding a given concentration), and the Concentration at Percentile (concentration at different probability levels). Selecting the 1% of the maximum, results in a probability plot at the 10-11 level.
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