Re: a question about color for overlapped plot

Hi Xianglei,

When you set your colormap to the BlueRed colormap, and then ask NCL to
grab the color green, NCL will try to get the color in your colormap
closest to green. In your case that would be black. There are two
possible solutions to this:
1) Use the function NhlNewColor to add the color green to your colormap.
gsn_define_colormap(wks,"BlueRed")
newcolor = NhlNewColor(wks,0.,1.0,0.)

http://www.ncl.ucar.edu/Document/Functions/Built-in/NhlNewColor.shtml

2) Merge another colormap that has green in it with the BlueRed colormap
using gsn_merge_colormaps:

http://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_merge_colormaps.shtml

Specifically, refer to the first example. Instead of specifiying gray
colors specify a green color or two. Remember that NCL has a 256 color
limit, so in your case you can only add 2 colors to your colormap..

Good luck,
Adam

Xianglei Huang wrote:
> Hi All,
>
> I am trying to use gsn_csm_streamline_contour_map_ce to creat a
> color contour plot overlapped with a streamline vector plot. I found
> that, after I choose colormap for contour plot, I cannot set the color
> of the streamlines as I want. For example, if I set
> gsn_define_colormap(wks,"BlueRed")
>
> And then if I try to plot streamlines in green by
> res@stLineColor = "green1"
>
> It will only plot out the streamlines in black. I tried other named
> color as well, the only color working as named is "white". All others
> cannot be plotted as named.
>
> Anyone know how I can go around this? Your help will be highly
> appreciated. Thanks.
>
> Xianglei
>
> -------------------------------------------------
> Xianglei Huang
> Princeton AOS Postdoctoral Research Associate
> NOAA Geophysical Fluid Dynamics Laboratory
> Princeton University Forrestal Campus
> 201 Forrestal Road
> Princeton, NJ 08540
>
> xianglei.huang_at_noaa.gov, xianglei_at_princeton.edu
> 609-452-6500 extension 6951 (office)
> 609-987-5063 (fax)
> http://www.princeton.edu/~xianglei
> -------------------------------------------------
>
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-- 
--------------------------------------------------------------
Adam Phillips			             asphilli_at_ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000	  http://www.cgd.ucar.edu/cas/asphilli
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