HYSPLIT Forum: hysplitbbs.arl.noaa.gov

What does each color (red, blue, green) in the ensemble trajectory plot represent?

"The ensemble form of the model automatically starts multiple trajectories from the selected starting point. Each member of the trajectory ensemble is calculated by offsetting the meteorological data by a fixed grid factor as defined in the Advanced Trajectory Configuration tab. The default offset is one meteorological grid point in the horizontal and 0.01 sigma units in the vertical. This results in 27 members for all-possible offsets in X, Y, and Z."

I only found this, is there more information anywhere else?

Best regards,

Kristine

After the model calculation has completed, use the normal Trajectory
Display tab to view the results. Because the offset is computed
in both directions in the vertical from the starting location, a
starting location at the ground would not provide an optimal
configuration for this type of simulation. The default vertical
offset is about 250 m. Therefore this should be the minimum
starting height for ensemble trajectories, unless the default
offset is changed in the namelist file.

More information can be found here:
http://www.ready.noaa.gov/documents/Tut ... ensem.html

Also, the colors do not represent anything in particular. It is only to distinguish the trajectories.