Re: setting cnLevelSelectionMode

From: Adam Phillips <asphilli_at_nyahnyahspammersnyahnyah>
Date: Wed, 04 Mar 2009 14:01:05 -0700

Hi Gina,

If you do not set cnLevelSelectionMode, NCL will determine what contour
levels to use *for each panel plot separately*... The label bar drawn at
the bottom of the panel plot will be representative of the contour
levels chosen in the last plot. Thus, each panel may have different
contour levels, even though a single label bar is drawn.

If, however, you do set cnLevelSelectionMode, then each panel plot is
drawn with the same contour levels, and the labelbar correctly applies
to each plot.

You can see what I mean by setting lbLabelBarOn = True, and by not
setting cnLevelSelectionMode.. Each panel will have different

Gina Henderson wrote:
> Hi there,
> I have a question about setting manual contour intervals in ncl. I am
> concerned because I created a panel plot for data using the "RasterFill"
> mode and added a common color bar. I then wanted to change the contour
> interval on the color bar and when I set my own contour values, the data
> values seemed to change. To check I set the manual levels to the same as
> what the default values had been (same max and min and breaks) and the
> two plots vary greatly.
> What I am concerned about is, how does the manual contour value option
> in ncl really work and why should setting this value manually (to the
> same value as the default) change the plot so drastically? I have
> attached two plots showing the difference between when I set the manual
> levels and when I do not.
> Any insight into this problem I would really appreciate,
> thanks, Gina.
> --
> Gina Henderson
> Graduate Student
> Department of Geography
> 215 Pearson Hall
> University of Delaware
> Newark DE
> 19718-2541
> Email: <>
> Ph: 302-831-2344
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Adam Phillips			   
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
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Received on Wed Mar 04 2009 - 14:01:05 MST

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