[ncl-talk] basic contour plot

[Mary Haley]

Olivier,

There's not enough information here for us to help you. First, it's
important that you "look at your data" and understand what you are
plotting.

Use "printVarSummary" to look at your data:

   printVarSummary(data)    ; "data" should be replaced by the variable you
are trying to plot

Does "data" contain lat/lon coordinate arrays, or do you have to read
lat/lon separately off the file?  Usually, if your data is not showing up
on a map it's because the lat/lon arrays have not been correctly specified.

You can read this description that explains how to correctly overlay data
on a map:

http://www.ncl.ucar.edu/Document/Graphics/overlays_on_map.shtml

Also, sometimes it's a "draw order" issue.  Your contours may be getting
draw under a filled map. If this is the case, you can try setting:

   res at cnFillDrawOrder = "postdraw"


It would help if we could see your script, and also the output from
"printVarSummary" of your variable.

Also, please take a look at the numerous plotting examples we have at:

http://www.ncl.ucar.edu/Applications/

Some simple "contour over a map" ones include:

http://www.ncl.ucar.edu/Applications/cylineq.shtml
http://www.ncl.ucar.edu/Applications/proj.shtml
http://www.ncl.ucar.edu/Applications/overlay.shtml

If you post more questions to ncl-talk, please review our posting
guidelines first:

http://www.ncl.ucar.edu/Support/posting_guidelines.shtml

These guidelines give you some pointers about where to look for help, and
how to best phrase your questions so that we can provide better answers.

Good luck,

--Mary




On Tue, Aug 4, 2015 at 1:23 PM, Olivier AMMON <ammonavis at hotmail.com> wrote:

> hello ncl users
>
>
> i did not manage to plot a contour and a map on the same plot that do not
> have contour color filled over the land on the map.
>
> i have to plot my contour area only over the sea on my plot.
>
> thanks
>
> regards
>
> olivier
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