[ncl-talk] plot native rotated projection

[Mary Haley]

Dear Mark,

I don't think your "rot1_plot_good.ncl" is plotting the data in the correct
location.  I say this because it looks like your contours have a rough
outline of what's supposed to be the Tibetan Plateau, but it doesn't look
like that's where it is on the map.

Also, If I modify your code so that it actually uses the lat/lon arrays you
read off the file to do the plotting, then the plot looks different.  It
does take longer to draw, because now you have to do the map transformation
calculation behind the scenes, but the plot looks more correct to me. I
just plotted it in a standard lat/lon projection, because when I use the
parameters you provided, part of the contours go outside of the plot
boundary.

Please compare the attached "rotated.png" image, which is from your
original rot1_plot.ncl script, and the "non_rotated.png" image, which is
the non-native image plotted using lat/lon arrays. I've called the script
that generates the non-native plot "rot1_plot_good_mod.ncl" and attached it
here as well.

Are you certain that you have the rotated parameters correct? This is
usually the cause of why native data doesn't appear in the correct location.

--Mary

On Wed, Aug 5, 2015 at 4:16 AM, Mark Chan <cym263 at yahoo.com> wrote:

> Dear Mary,
>
> Thanks so much for your response to my question!
> The attached files are my ncl scripts and input data, and the script
> 'rot1_plot_good.ncl' works but 'rot2_plot_failed.ncl' always failed. Can
> you help to make the second script work?
>
> Actually I am trying to plot the rotated projection from WRF simulation (
> see the attached namelist.wps), and wondering how to use the rotated
> message (such as: pole_lat = 77.61, pole_lon = -64.78) in my plot, so the
> plot could be exactly same as the model simulation (same as the ncview
> shows).
>
> In addition, using the rotated message (77.61, -64.78), how is it possible
> to plot a global map, which shows the 'rotated map' looks like globally?
>
> Thanks very much!
> Mark
>
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