2.2 Test Trajectory Calculation

From the top bar of the main menu select the Trajectory / Setup Run tab to open the setup menu. Press the Save button to close the menu, accepting the default settings. Then select the Trajectory / Run Model tab which immediately starts the trajectory model calculation. When it completes, press the Exit button to close the window. Then select the Trajectory / Display / Trajectory tab to open the display menu. Press the Execute Display button to show the test case trajectory result.

1. The Setup Run menu creates a file named CONTROL in the working directory with the starting time, location, meteorological data file name, and trajectory endpoints output file name.


2. The Run Model tab starts the trajectory model simulation which creates an ASCII output file called tdump with the endpoint locations.


3. The Display Trajectory tab runs the trajectory plotting program which reads the tdump endpoints file and creates the SVG graphics file called trajplot.html. Other graphical formats are available using Python display option, which will be discussed in more detail in a later section.


4. The SVG file is automatically displayed using the default browser. Multiple frame graphics can be advanced using the navigation buttons.


5. These files can all be found in the HYSPLIT working directory and in addition to the above named files the directory also contains diagnostic files such as MESSAGE, TRAJ.CFG, and if needed WARNING.

The display of the trajectory 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.

The display of the three-trajectory graphic means that all the HYSPLIT components have been correctly installed. In subsequent simulations, the three individual steps: configuring the model simulation, running the simulation, and converting the output to a graphical format will be explored in more detail individually. Many of the features available through the GUI apply to trajectory as well as air concentration calculations. After testing the air concentration simulation in the next section, we will continue with the trajectory calculations in more detail.