[ncarg-talk] NCL Contour Plotting

[Neil Weston - NOAA Federal]

NCL Users,

I have a netcdf file with 'z' data that ranges from 0 to 1.76. The NCL
script below overlays contours on a map of North America.  However, I have
noticed that data from 0.5 to 1.2 are not plotted even though measurements
with values in that range do exist in the netcdf dataset.  I verified this
by plotting the 'z' values in the dataset using Generic Mapping Tools (GMT)
as well as using ncdump to look at the data.

I may have overlooked something but if you have any suggestions to plot
these values, I would sincerely appreciate them.  The short NCL script is
below.

Kind regards,
Neil
----------
ncdump header and NCL script below

netcdf horizontal-high {
dimensions:
        x = 4601 ;
        y = 3001 ;
variables:
        double x(x) ;
                x:long_name = "x" ;
                x:actual_range = -170., -55. ;
        double y(y) ;
                y:long_name = "y" ;
                y:actual_range = 5., 80. ;
        float z(y, x) ;
                z:long_name = "z" ;
                z:_FillValue = NaNf ;
                z:actual_range = 0.000674999959301203, 1.76100623607635 ;

// global attributes:
                :Conventions = "COARDS, CF-1.5" ;
                :title = "" ;
                :history = "grdsample horizontal.nc -Ghorizontal-high.nc
-I0.025/0.025" ;
                :description = "" ;
                :GMT_version = "5.3.2 (r17593) [64-bit]" ;

----------------

begin

   cdf_file = addfile("horizontal-high.nc","r")
   ;cdf_file = addfile("vertical-high.nc","r")
   shift = cdf_file->z(:,:)
   lat = cdf_file->y
   lon = cdf_file->x
   shift at long_name = ""
   lat at long_name = ""
   lon at long_name = ""

   wks = gsn_open_wks("x11","overlay")

   ; define resources
   mpres = True
   mpres at gsnDraw = False
   mpres at gsnFrame = False
   res = mpres
   cnres = mpres

   ; contour
   cnres at cnFillOn = True
   cnres at cnLinesOn = False
   cnres at cnInfoLabelOn = False
   cnres at cnFillPalette = "MPL_jet"
   ;cnres at cnFillPalette = "BkBlAqGrYeOrReViWh200"
   ;cnres at cnFillPalette = "horizontal"
   cnres at lbOrientation = "Vertical"
   ;cnres at lbTitleString = "Horizontal Shift"
   cnres at lbTitlePosition = "Left"
   cnres at lbBoxLinesOn = False
   cnres at lbTitleFontHeightF = 0.015
   cnres at lbLabelFontHeightF = 0.01


   cnres at sfXArray = lon
   cnres at sfYArray = lat
   cnres at cnLevelSelectionMode = "ManualLevels"
   cnres at cnMinLevelValF = 0.0
   cnres at cnMaxLevelValF = 2.0
   cnres at cnLevelSpacingF = 0.1
   cnres at cnLineLabelsOn = False

   ; make sure contours are drawn in "predraw" phase
   cnres at cnFillDrawOrder = "Predraw"

   ; map
   mpres at tiMainString = "Horizontal Shift (m)"
   mpres at mpFillOn = False
   mpres at mpMaxLatF = 80
   mpres at mpMinLatF = 5
   mpres at mpMinLonF = -170
   mpres at mpMaxLonF = -55
   mpres at mpOutlineOn = True
   mpres at mpOutlineDrawOrder = "PostDraw"

   ; create but don't draw contours, maps, vectors etc.
   cnid = gsn_csm_contour(wks,shift,cnres)
   mpid = gsn_csm_map(wks,mpres)

   ; overlay contour, streamline and vector plots on the map plot
   overlay(mpid,cnid)

   draw(mpid)
   frame(wks)

end
------------------------------------------------------------
------------------------------------------------------------------------
Dr. Neil D. Weston

Technical Director
OCS, National Ocean Service, NOAA
SSMC3, Rm 7806
1315 East West Hwy, Silver Spring, MD 20910

301-713-2801 <(301)%20713-2801>     240-278-7194 <(240)%20278-7194>
301-713-4501 <(301)%20713-4501>      neil.d.weston at noaa.gov
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