Is it possible to overlay several trajectories onto one map?


You can plot multiple trajectories on one plot using the HYSPLIT program trajplot. On the Windows version it is c:\hysplit4\exec\trajplot.exe. You run this from the Command Prompt. If you only have a few files, say 3 files named tdump1, tdump2, and tdump3:

c:\hysplit4\exec\trajplot.exe -itdump1+tdump2+tdump3. [note the “-i” then the filenames].

If you have many files you can use notepad to make a text file listing the filenames, say named INFILE:

c:\hysplit4\exec\trajplot.exe -i+INFILE

INFILE would be as follows:
c:\hsyplit4\working\tdump1
c:\hysplit4\working\tdump2
c:\hysplit4\working\tdump3

c:\hysplit4\working\tdumpN

In both of these cases, the map is scaled based on the first tdump file. You can rearrange the order of the tdump files and/or change the zoom to get the desired map domain. Alternatively, you can merge the tdumps into one large tdump file, then the map domain will be set based on all the trajectories. To do this using the same INFILE:

c:\hysplit4\exec\merglist -i+INFILE

Output file is named mdump.

Other parameters such as zoom (-z) are described if you run trajplot without any parameters.

If you are running the trajectories on the web, save the endpoints files (typically named tdump) to run the PC plotting program to combine the trajectories.

Barbara Stunder