[ncl-talk] questions about time-height contour plot

Mary Haley haley at ucar.edu
Mon Jul 31 15:07:55 MDT 2017

Dear Ying Song,

The gsn_csm_pres_hgt function assumes that you have a 1D array of levels
that represents the levels across each X value, so yes, in this case, you
would need to interpolate your various levels to the same 1D array.

I think the correct thing to do is create the nlev x ntimes array and
populate it yourself, and then use gsn_csm_contour to simply draw a filled
contour plot.  Of course, you won't get the "nice" pressure/height values
on the Y axis, but this isn't going to be possible anyway, if these are
different for every X value.

If you really want a pressure/height axis, then you will need to vertically
interpolate your pressure levels to a common set of pressure levels for
each set of daily values. If this is the route you want to go, then go to
our "interpolation functions" page:


and search for words like "vertical" and "pressure" to see what routines
have to do with vertical or pressure interpolation.


On Tue, Jul 25, 2017 at 2:02 PM, Ying Song <ysong4 at slu.edu> wrote:

> Hello,
> I has a question about plot daily vertical profiles over time in NCL. I
> have one month daily ozonesonde from flight in .ict format and hope to plot
> the daily profiles over time. (just like the left picture on the webpage:
> http://ozone.met.psu.edu/dev/research/discover2014/
> quicklooks_ozonesondes.php )
> The My thought is to define a new array (/nlev, ntimes/), write the 30
> days' ozonesonde into one array, use "gsn_csm_pres_hgt" to plot. However,
> the nlev are different among my daily profiles. Do I have to preprocess my
> profiles to get uniform vertical level or NCL can handle it directly? Do
> you have an example that I can check?
> Thank you very much!
> --
> Ying Song, PhD, Post Doctoral Fellow
> Department of Earth and Atmospheric Sciences
> Saint Louis University
> ysong4 at slu.edu
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