2.4 Test Air Concentration Calculation


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From the top bar of the main menu select the Concentration / Quick Start / Run Example menu tabs. The Run Example tab initiates a windows only program that displays a source selection menu. A left-click resets the source location, while a right-click closes the selection window. For the purposes of this test, just right-click to accept the default location, which then results in window termination message. Select Yes and then ...

  1. A CONTROL file is created which contains the starting time, location, name of the meteorological data file, details of the pollutant emission, concentration grid, and output file name.

  2. The concentration model is then run which creates a binary gridded concentration output file called cdump.

  3. A concentration plotting program is run which reads the binary air concentration cdump file to create the Postscript graphics file concplot.ps.

  4. The final plume Postscript graphic is displayed using Ghostview.

  5. All the output files are written to the HYSPLIT working directory and in addition to the above named files the directory also contains diagnostic files such as MESSAGE, VMSDIST, CONC.CFG, and if needed WARNING.

  6. The Quick Start menu is the easiest way to enter the latititude-longitude of a new location from a map if no other detailed source information is available. The model simulation will use all the other settings from the last simulation.

The display of the air concentration plume graphic means that all the HYSPLIT components have been correctly installed. In the unlikely event that the installation failed and the graphic was not displayed suggests that there may be issues requiring system administrator support. Consider the following:

  • You have permission to install software.
  • You have write permission to the directories in which the software was installed.
  • You are not installing on top of a previous version of HYSPLIT.

Because a plume simulation may consist of thousands of individual trajectories but with an additional turbulent component to the motion to account for atmospheric dispersion, the simpler trajectory calculation will be explored first in more detail in the next few sections.