Re: overlaying gradient contours

[1]
These are *not* two-dimensional latitude or longitude arrays.
The variables u and vdiv are two-dimensiona BUT the
coordinate variables are classic netCDF one dimensional
coordinates.

By Unidata/netCDF definition a "coordinate variable"
is a one-dimensional array of monotonically {in/de}creasing
values"

Variable: u
Type: float
Total Size: 42048 bytes
            10512 values
Number of Dimensions: 2
Dimensions and sizes: [lat | 73] x [lon | 144]
Coordinates:
            lat: [90..-90] <=== coord variable
            lon: [ 0..357.5] <=== coord variable

Remove:
  lat2d = f->lat
  lon2d = f->lon
printVarSummary(lat2d)
printVarSummary(lon2d)

u_at_lon2d=lon2d
u_at_lat2d=lat2d
v_at_lon2d=lon2d
v_at_lat2d=lat2d

[2] Delete or comment the following

  res1_at_mpMinLonF = 0. ; select a subregion
  res1_at_mpMaxLonF = 360.
  res1_at_mpMinLatF = -90.
  res1_at_mpMaxLatF = 90.

The default is a global grid.

======================================
Good luck

Chris Fletcher wrote:
> Hi, question from a new user:
>
> I am trying to use gsn_csm_contour_map_overlay to display an NCEP/NCAR
> reanalysis wind field (shaded) and its meridional gradient (contour).
>
> However, the contour data won't plot correctly (it appears compressed
> into a smaller region in the top-right -- see attached). I believe the
> lon/lat2d variables and their "units" attribute are defined correctly
> (although the warnings suggest otherwise). The problem appears to be
> that the gradsf procedure modifies the coordinates somehow, because I
> can contour overlay the wind field with itself without a problem.
>
> Thanks in advance, all the output follows.
> Chris
>
>
>
> I see the following warnings from my script:
> (0) is_valid_latlon2d_attr: Warning: The 'lat2d' attribute must
> either be the same dimension sizes as the data, or one element larger in
> both directions. Your data will most likely not be overlaid on the map
> correctly.
> (0) is_valid_latlon2d_attr: Warning: The 'lon2d' attribute must
> either be the same dimension sizes as the data, or one element larger in
> both directions. Your data will most likely not be overlaid on the map
> correctly.
> (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'
>
>
>
> ;Here are the details from printVarSummary
> ;***********************************************
> Variable: lat2d
> Type: float
> Total Size: 292 bytes
> 73 values
> Number of Dimensions: 1
> Dimensions and sizes: [lat | 73]
> Coordinates:
> lat: [90..-90]
> Number Of Attributes: 3
> units : degrees_north
> actual_range : ( 90, -90 )
> long_name : Latitude
>
>
> Variable: lon2d
> Type: float
> Total Size: 576 bytes
> 144 values
> Number of Dimensions: 1
> Dimensions and sizes: [lon | 144]
> Coordinates:
> lon: [ 0..357.5]
> Number Of Attributes: 3
> units : degrees_east
> long_name : Longitude
> actual_range : ( 0, 357.5 )
>
>
> Variable: u
> Type: float
> Total Size: 42048 bytes
> 10512 values
> Number of Dimensions: 2
> Dimensions and sizes: [lat | 73] x [lon | 144]
> Coordinates:
> lat: [90..-90]
> lon: [ 0..357.5]
> Number Of Attributes: 15
> lat2d : <ARRAY of 73 elements>
> lon2d : <ARRAY of 144 elements>
> long_name : Monthly mean u wind
> actual_range : ( -66.37, 124.4 )
> valid_range : ( -125, 160 )
> units : m/s
> missing_value : 32766
> precision : 2
> least_significant_digit : 1
> var_desc : u-wind
> U
> dataset : CDC Derived NCEP Reanalysis Products
> AC
> level_desc : Multiple levels
> F
> statistic : Mean
> M
> parent_stat : Other
> -
> _FillValue : 32766
>
>
> Variable: vdiv
> Type: float
> Total Size: 42048 bytes
> 10512 values
> Number of Dimensions: 2
> Dimensions and sizes: [lat | 73] x [lon | 144]
> Coordinates:
> lat: [90..-90]
> lon: [ 0..357.5]
> Number Of Attributes: 15
> _FillValue : 32766
> parent_stat : Other
> -
> statistic : Mean
> M
> level_desc : Multiple levels
> F
> dataset : CDC Derived NCEP Reanalysis Products
> AC
> var_desc : v-wind
> V
> least_significant_digit : 1
> precision : 2
> missing_value : 32766
> units : m/s
> valid_range : ( -125, 160 )
> actual_range : ( -66.65, 66.39 )
> long_name : Monthly mean v wind
> lon2d : <ARRAY of 144 elements>
> lat2d : <ARRAY of 73 elements>
>
>
>
> Here is my script:
> ;***********************************************
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> ;*************************************************
> begin
> ;*************************************************
> dir = "/home/cgf/projects/"
> f = addfile (dir+"uwnd200.nc", "r")
> u = f->uwnd ; (lat,lon)
> lat2d = f->lat
> lon2d = f->lon
> f2 = addfile (dir+"vwnd200.nc", "r")
> v = f2->vwnd
> printVarSummary(lat2d)
> printVarSummary(lon2d)
>
> u_at_lon2d=lon2d
> u_at_lat2d=lat2d
> v_at_lon2d=lon2d
> v_at_lat2d=lat2d
> udiv=u
> vdiv=v
> gradsf(u,udiv,vdiv)
> ;
> ; ************
> ; plotting
> ;
> ;
> wks = gsn_open_wks("ps","wind") ; open a workstation
> gsn_define_colormap(wks,"BlWhRe")
> ;************************************************
> ; resource list for first data array
> ;************************************************
> res1 = True
> res1_at_gsnDraw = False ; don"t draw
> res1_at_gsnFrame = False ; don"t advance frame
>
> res1_at_cnLevelSelectionMode = "ManualLevels" ; set manual contour levels
> res1_at_cnMinLevelValF = -5. ; set min contour level
> res1_at_cnMaxLevelValF = 45. ; set max contour level
> res1_at_cnLevelSpacingF = 2 ; set contour spacing
>
> res1_at_lbOrientation = "Vertical" ; vertical label bar
> res1_at_lbLabelAutoStride = True ; optimal label stride
> res1_at_gsnSpreadColors = True ; use full range of colors
> res1_at_gsnSpreadColorEnd = -3 ; don"t use added gray
>
> ; res1_at_mpCenterLonF = 180. ; center plot at 180
>
> res1_at_mpMinLonF = 0. ; select a subregion
> res1_at_mpMaxLonF = 360.
> res1_at_mpMinLatF = -90.
> res1_at_mpMaxLatF = 90.
>
> ;************************************************
> ; resource list for second data array
> ;************************************************
> res2 = True
> res2_at_cnLevelSelectionMode = "ManualLevels" ; set manual contour levels
> res2_at_cnMinLevelValF = -10. ; set min contour level
> res2_at_cnMaxLevelValF = 10. ; set max contour level
> res2_at_cnLevelSpacingF = 0.5 ; set contour spacing
> res2_at_cnLineLabelsOn = True
> res2_at_gsnContourZeroLineThicknessF = 2. ; doubles thickness of
> zero contour
> res2_at_gsnContourNegLineDashPattern = 1 ; sets negative contours
> to dash pattern 1
>
> printVarSummary(u)
> printVarSummary(vdiv)
>
> plot=gsn_csm_contour_map_overlay(wks,u,vdiv*1e5,res1,res2)
> draw(plot)
> frame(wks)
> end
>
>
>
>
>
>
>
>
>
>
> -----------------------------------------------
> Chris Fletcher, Research Associate
> + Dept. of Physics, U. of Toronto, 60 St. George St.,Toronto, ON, M5S
> 1A7, Canada.
> + Tel: +1-416-946-0344
> + Home page: http://www.atmosp.physics.utoronto.ca/people/cgf/
> -----------------------------------------------
>
>
>
>
> ------------------------------------------------------------------------
>
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Received on Fri Aug 14 2009 - 08:07:28 MDT