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Trajectory info

Posted: November 11th, 2016, 2:56 am
by jonhsame
I want to plot trajectories for some episode. I have few queries.
1) At what GMT I should plot my trajectories?
2) I am plotting the back air trajectories so how many days I should select . At present I am checking for dust and selecting 5 days.
3) At present I am trying to plot at 3 altitudes , 500 m AGL , 2000 and 3000 m AGL, which is random at present , what height I should plot and whether AGL or AMSL heights.

I shall be very thankful to you.


Re: Trajectory info

Posted: November 15th, 2016, 1:10 am
by Ntwali

Please I need some help from you:

1. I can't access archive data using Hysplit unregistered version, what should be the reason?

2. How to run seasonal trajectories as the archive data are not organized by seasons?

Hope to hear from you



Re: Trajectory info

Posted: November 15th, 2016, 9:14 am
by glenn.rolph
We need more information on what archive data sets and what dates you cannot access from the GUI (provide screen prints if possible).

In order to run seasons, you will need to download the data files and add them to the CONTROL file either manually or through the GUI for the season you are interested in (multiple files are allowed).

Re: Trajectory info

Posted: December 26th, 2016, 9:36 am
by Ntwali
Thanks for your help.

I will try accordingly.

Re: Trajectory info

Posted: January 10th, 2017, 9:03 pm
by Ntwali
Dear Glenn Rolph,

I have tried to run seasonal backward trajectories but still I just keep getting the trajectory of the last month not the all season.

E.g. I have put NCEP data of 3 months (201103, 201104, 201105) in Hysplit GUI to run MAM (March-April-May) seasonal backward trajectories and I got the output trajectory of only May.

Please can you guide me and tell me where I made a mistake? I have tried to attach a picture of trajectory setup but I got a message saying ''invalid file extension''!

Hope to hear from you.

Kind regards

Ntwali Didier

Re: Trajectory info

Posted: January 11th, 2017, 8:27 am
by glenn.rolph
You can only run 1 month at a time if you are using the Special Runs/Daily option in the HYSPLIT GUI (for details on how to run this see: ... _freq.html ). If you want to run more than one month at a time you can use the trajectory restart option in the Advanced/Trajectory menus, however you won't be able to use the trajectory frequency plotting program as each trajectory needs to be in its own file.

For the trajectory frequency program, you will need to set it up for each month you are interested in (traj1.png and traj2.png) and run them all with the same output file extension such as fdump. Once you run all three months you can display the trajectory frequency by choosing Trajectory/Display/Frequency, create the file of trajectory filenames (fdump) and set the other options (traj3.png) as you please and you will get a trajectory frequency plot for all your trajectories in the 3 months (freqplot.gif).

An example is shown in the attached images. (you should have been able to add image attachments to your post.

Re: Trajectory info

Posted: January 12th, 2017, 12:01 pm
by Ntwali
Dear Glenn Rolph,

Thank you so much for your kind help and your time. I really appreciate your guidance.

I have followed your advices step by steps and now it works.

Kind regards.