[ncl-talk] Lambert Conformal coordinate issue

[Rick Brownrigg]

Hi Forrest,

I think the issue was that the variables to be plotted did not have
coordinates associated with them.  I added the highlighted lines to your
script:

  u     = f->UGRD_P0_L7_GLC0

  v     = f->VGRD_P0_L7_GLC0

  refc  = f->REFC_P0_L200_GLC0

  lat2d = f->gridlat_0

  lon2d = f->gridlon_0

  rot   = f->gridrot_0                   ; (lat,lon)



  refc at lat2d = lat2d

  refc at lon2d = lon2d

  u at lat2d = lat2d

  u at lon2d = lon2d

  v at lat2d = lat2d

  v at lon2d = lon2d

This is all described at:

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

I'll send you two plots offline.  The one with the _fullextent suffix is
what I initially got. The coordinates do indeed range across the entire
CONUS, but there are many missing values in the "refc" variable.  I
eyeballed these coordinates to get the "_zoomed" plot:

  cnres at mpLeftCornerLatF  = 35.; lat2d at corners(0)

  cnres at mpLeftCornerLonF  = -85. ;lon2d at corners(0)

  cnres at mpRightCornerLatF = 47.; lat2d at corners(2)

  cnres at mpRightCornerLonF = -62. ;lon2d at corners(2)

There are still a few issues that hopefully you can resolve:

i) the center of projection is not appropriate for the zoomed in plot;
 more likely it should be the center latitude of the zoomed in area

ii) the vectors should probably be scaled

iii) I don't know why the "reference vector" does not appear on the zoomed
plot???

I hope that helps...
Rick


On Thu, Sep 22, 2016 at 8:13 AM, Black, Forrest (LARC-D318)[UNIVERSITIES
SPACE RESEARCH ASSOCIATION] <forrest.black at nasa.gov> wrote:

> Hello fellow NCL users,
>
>
>
> I am using a script in version 6.3.0 to overlay wind data from onto a
> reflectivity contour plot. I am using RAP data which uses a lambert
> conformal projections. When I just plot the wind on a vector plot there is
> no issue. However, when I overlay the vector plot onto a contour plot the
> following error message appears:
>
>
>
>
>
> (0)     check_for_y_lat_coord: Warning: Data either does not contain a
> valid latitude coordinate array or doesn't contain one at all.
>
> (0)     A valid latitude coordinate array should have a 'units' attribute
> equal to one of the following values:
>
> (0)         'degrees_north' 'degrees-north' 'degree_north' 'degrees north'
> 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg north'
>
> (0)     check_for_lon_coord: Warning: Data either does not contain a valid
> longitude coordinate array or doesn't contain one at all.
>
> (0)     A valid longitude coordinate array should have a 'units' attribute
> equal to one of the following values:
>
> (0)         'degrees_east' 'degrees-east' 'degree_east' 'degrees east'
> 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
>
> warning:ContourPlotDraw: out of range coordinates encountered; standard
> AreaFill rendering method may be unreliable;
>
> consider setting the resource trGridType to "TriangularMesh" if
> coordinates contain missing values
>
>
>
> The data plots, but the reflectivity does not to be georeferenced
> correctly. If you have any clue on what to fix please let me know. The data
> used is on the ftp site under “fblack_sample.grb 2”.
>
>
>
> Thanks for any assistance you can provide.
>
>
>
> -        Forrest Black
>
>
>
>
>
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