8.1 Configure for CAPTEX Release #2


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Most of the essential HYSPLIT model parameters have been discussed in the previous sections. Now we will review in detail all the changes required to configure the model to simulate CAPTEX release number 2 and produce the animation shown in the introductory section.

  1. First press the center Reset button on the main GUI to clear all previous changes and then press Concentration / Setup Run to open the concentration setup menu. Make all the changes shown:

    • change the starting time to 83 09 25 17,
    • change the starting location to 39.90 -84.22 10.0,
    • make the total run time 68 hours, which is when the last air sample is collected,
    • and clear and set the meteorology file to captex2_wrf27uw.bin.

  2. Now press the large center button labeled Pollutant, Deposition, and Grids Setup to open the main selection menu. Start with the top left radio-button for species #1 to open the pollutant menu.

    • Enter the 4-character identification field, PMCH, for the material released (per fluro mono methyl cyclo hexane),
    • the hourly release rate, 67000 grams,
    • and the emission duration of 3.0 hours, which will result in a total release of 201 kg. The emission units are totally arbitrary as HYSPLIT only computes the dilution factor of any mass that is released. So if the emission units are grams then the air concentrations will be grams per cubic meter.
    • Leave the emission starting times as all zeros. When this field is zero, the emissions start at the beginning of the simulation. Save to close the menu.

  3. Now press the center column radio-button for grid #1 to open the menu to define the characteristics of concentration grid #1.

    • Start by defining the center of the concentration grid approximately centered over the sampling domain 42.0 -78.0. A zero in this field forces the grid center to be the release location.
    • Change the grid spacing to 0.25 in both directions. This should be sufficient for the large source to receptor distances of this experiment.
    • Change the grid span to 15.0 degrees latitude and 25.0 degrees longitude.
    • The output file will be written to the startup working directory (./) and give the binary concentration output file a unique name such as hysplit2.bin.
    • The concentration grid only needs one 100 m layer. When vertical particle dispersion is enabled, the heights represent layer tops, in this case from ground-level (0) to 100 m.
    • Now explicitly set the start (83 09 25 18 00) and stop (83 09 28 15 00)times for the integration time on the concentration grid. Leaving the field as zeros starts the summation at the start of the run. But in this case we want the concentration grid times to match the actual times air samples were collected, which started at 18Z rather than the start of the release at 17Z.
    • Air concentration samples were collected over 3 or 6 hours, therefore a 3 hour average covers all the possibilities (two 3h periods can be averaged together).

  4. Now press the right column radio-button for species #1 deposition options. The PMCH tracer released does not deposit and therefore all these fields will remain zero. The menu has some pre-set values which will be discussed in more detail in a later section.

  5. Now press the Advanced / Concentration Setup / Concentration menu tab to open the namelist selection menu. Only two menus need to be changed.

    • Open menu #4, the particle/puff release number limits and change the default particle release number from 2500 to 50000 and the maximum particle number from 10000 to 100000. Because the default mode is 3D particle, we know from the previous sections that the default is insufficient for a 3 day duration simulation.
    • Open menu #9, the input and output of particle files and change the first output time from 0 to 1 hour and repeat interval from 0 to 3 so that the particle output time will be at the same time as the concentration grid output times. The PARDUMP output file will be used for display purposes in the next section.
    • Save each menu and the selection menu to close out the Concentration Setup section.

  6. Now from the main menu select Concentration / Run Model and when the simulation completes continue on to the next section to review all the concentration display options.

After the simulation run has completed, it will take about 12 minutes, open the MESSAGE file to confirm that indeed 201 kg have been released and that concentrations (condsk) and particle positions (parout) were output every three hours. If satisfied, go back and save all the changes to the control and namelist file menus through Save As to captex_control.txt and captex_setup.txt for future examples.