how to read the lon&lat from the dat file and use them to plot graph?

[Li Li <li.li@xxxxxxx>]

Hi there,
Now I have a dat form file for the longitude and latitude. I can access them
by ferret, but how can I use them to combine with the cdf file and make
graphs?
Actually, I have xlon,ylat, xdis, ydis in this dat file, x-distance is the
variable now in cdf file which goes with the right x-longitude.

Now I want to use the longitude to substitude the x-distance to make graphs,
how can I do it?
Thanks a lot!
Lily