[ncl-talk] Data projected in a Wrong Location on Map
Mansur Ali Jisan
jisan.mansur at gmail.com
Mon Dec 3 13:29:57 MST 2018
Dear Mary,
Thank you for the suggestions. I made modifications according to the
suggestion but now the storm center is not showing in the domain (figure
attached). It looks to me that the lat long values are still not attached
with the variable u that I'm trying to plot. I also looked at the example
plots in the NCL website but couldn't able to figure it out.
The *PrintVarSummary* for *u *variable is:
Variable: u
Type: float
Total Size: 560583952 bytes
140145988 values
Number of Dimensions: 3
Dimensions and sizes: [time | 97] x [lat | 1202] x [lon | 1202]
Coordinates:
time: [ 0.. 0]
lat: [ 1..1202]
lon: [ 1..1202]
Number Of Attributes: 1
units : m/s
The *PrintVarSummary *for *lat *is:
Variable: lat
Type: float
Total Size: 4808 bytes
1202 values
Number of Dimensions: 1
Dimensions and sizes: [1202]
Coordinates:
The *PrintVarSummary *for *lon *is:
Variable: lon
Type: float
Total Size: 4808 bytes
1202 values
Number of Dimensions: 1
Dimensions and sizes: [1202]
Coordinates:
And here's the *modified code*:
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
begin
;---Read data
f1 = addfile("boundary_parametric.nc","r")
u = f1->u10 ; 97 x 1202 x 1202
lat = fspan(13,47,1202)
lon = fspan(-95,-48,1202)
printVarSummary(lat)
printVarSummary(lon)
u!1="lat"
u!2="lon"
u&lat at units = "degrees_north"
u&lon at units = "degrees_east"
printVarSummary(u)
;---Start the graphics
wks = gsn_open_wks("png","irma-u10")
gsn_define_colormap(wks,"matlab_jet")
;---Set some resources
res = True
res at gsnMaximize = True ; maximize plot in frame
res at gsnAddCyclic = False
res at cnFillOn = True ; turn on contour fill
res at cnLinesOn = False ; turn off contour lines
res at cnLineLabelsOn = False ; turn off contour line labels
res at gsnScalarContour = True ; contours desired
res at tiMainString = "Hurricane Irma"
res at trGridType = "TriangularMesh"
res at gsnScalarContour = True
res at cnLevelSelectionMode = "ManualLevels"
res at cnMinLevelValF = 0
res at cnMaxLevelValF = 40
res at cnLevelSpacingF = 5
res at mpProjection = "CylindricalEquidistant" ;
projection
res at mpDataBaseVersion = "MediumRes"
res at mpLimitMode = "LatLon"
res at mpMinLatF = 13.0
res at mpMaxLatF = 47.0
res at mpMinLonF = -95.0
res at mpMaxLonF = -48.0
plot = gsn_csm_contour_map(wks,u(3,:,:),res)
end
On Mon, Dec 3, 2018 at 11:10 AM Mary Haley <haley at ucar.edu> wrote:
> Dear Mansur,
>
> There are a couple of issues with your script.
>
> The first is that you are setting:
>
> res at tfDoNDCOverlay = True ; do not
> transform data
>
> This tells NCL to ignore any lat/lon information attached to your data,
> and to instead assume that the map resources (res at mpXXXX) have been set
> up exactly to match the projection of your data. Remove that line.
>
> The second is that you are providing conflicting information to the
> plotting program by adding too much lat/lon information to your data
> variable. You have:
>
> lat2d = fspan(13,47,1202)
> lon2d = fspan(-95,-58,1202)
> printVarSummary(u)
> printVarSummary(lat2d)
> printVarSummary(lon2d)
> u!1="lat2d"
> u!2="lon2d"
>
> u at lat2d=lat2d
> u at lon2d=lon2d
>
> u&lat2d at units = "degrees_north"
> u&lon2d at units = "degrees_east"'
>
> The first issue is that these two lines should NOT be set at all:
>
> u at lat2d=lat2d
> u at lon2d=lon2d
>
> They are only to be used in the case where you have curvilinear data,
> which is data represented by two-dimensional lat/lon arrays. The way you
> are setting up your lat/lon arrays is for rectilinear data, which means you
> have one-dimensional latitudes for all your Y locations, and
> one-dimensional longitudes for your X locations.
>
> While it's not wrong, I suggest not using "lat2d" and "lon2d" for your lat
> / lon variable names, because this is misleading. Instead, I suggest:
>
> lat = fspan(13,47,1202)
> lon = fspan(-95,-58,1202)
> printVarSummary(u)
> printVarSummary(lat)
> printVarSummary(lon)
> u!1="lat"
> u!2="lon"
>
> u&lat at units = "degrees_north"
> u&lon at units = "degrees_east"'
>
> To learn more about rectilinear versus curvilinear, you might want to see
> the "plotting data on a map" examples page:
>
> http://www.ncl.ucar.edu/Applications/plot_data_on_map.shtml
>
> Regards,
>
> --Mary
>
>
> On Sun, Dec 2, 2018 at 9:28 PM Mansur Ali Jisan <jisan.mansur at gmail.com>
> wrote:
>
>> Dear NCL Community,
>>
>> I'm facing some problems in projecting my data properly on a map. I'm
>> working with a NetCDF file from a parametric wind model for the case of
>> Hurricane Irma. The variable that I'm trying to plot is u10. The problem is
>> that it doesn't have any coordinate values attached to it. But from the
>> input data, I know the extent of latitude and longitude. So, I defined that
>> in the NCL script but from the visualization, the location of the center
>> position was shown in a wrong position.
>>
>> Following is the script that I tried:
>>
>> *load *"$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> *load* "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>> begin
>> ;---Read data
>> f1 = addfile("boundary_parametric.nc","r")
>> u = f1->u10 ; 97 x 1202 x 1202
>> lat2d = fspan(13,47,1202)
>> lon2d = fspan(-95,-58,1202)
>> printVarSummary(u)
>> printVarSummary(lat2d)
>> printVarSummary(lon2d)
>> u!1="lat2d"
>> u!2="lon2d"
>>
>> u at lat2d=lat2d
>> u at lon2d=lon2d
>>
>> u&lat2d at units = "degrees_north"
>> u&lon2d at units = "degrees_east"
>>
>> printVarSummary(u)
>>
>>
>> ;---Start the graphics
>> wks = gsn_open_wks("png","irma-u10")
>> gsn_define_colormap(wks,"matlab_jet")
>> ;---Set some resources
>> res = True
>> res at gsnMaximize = True ; maximize plot in frame
>> res at gsnAddCyclic = False
>> res at cnFillOn = True ; turn on contour fill
>> res at cnLinesOn = False ; turn off contour lines
>> res at cnLineLabelsOn = False ; turn off contour line labels
>> res at gsnScalarContour = True ; contours desired
>> res at tiMainString = "Hurricane Irma"
>> res at trGridType = "TriangularMesh"
>> res at gsnScalarContour = True
>> res at cnLevelSelectionMode = "AutomaticLevels"
>> res at mpProjection = "CylindricalEquidistant" ;
>> projection
>> res at mpDataBaseVersion = "MediumRes" ; use more
>> detailed maps
>> res at mpLimitMode = "LatLon"
>> res at mpMinLatF = 13.0
>> res at mpMaxLatF = 47.0
>> res at mpMinLonF = -95.0
>> res at mpMaxLonF = -58.0
>> res at tfDoNDCOverlay = True ; do not
>> transform data
>>
>> plot = gsn_csm_contour_map(wks,u(3,:,:),res)
>>
>> end
>>
>> *NCL_Filedump* for the input file is the following:
>>
>> Variable: f
>> Type: file
>> filename: boundary_parametric
>> path: boundary_parametric.nc
>> file global attributes:
>> time-units : start time: 2017-09-10 00:06:00 +00:00
>> dimensions:
>> y_axis = 1202
>> x_axis = 1202
>> time = 97 // unlimited
>> variables:
>> double y_axis ( y_axis )
>> units : unit-less
>>
>> double x_axis ( x_axis )
>> units : unit-less
>>
>> float time ( time )
>> units : hours
>>
>> float utx ( time )
>> units :
>>
>> float uty ( time )
>> units :
>>
>> float rmax ( time )
>> units :
>>
>> float wsmax ( time )
>> units :
>>
>> float u10 ( time, y_axis, x_axis )
>> units : m/s
>>
>> float v10 ( time, y_axis, x_axis )
>> units : m/s
>>
>> float utop ( time, y_axis, x_axis )
>> units : m/s
>>
>> float vtop ( time, y_axis, x_axis )
>> units : m/s
>>
>> Please let me know if any additional information needed.
>>
>> Thanks in advance!
>>
>> Mansur
>>
>> --
>> *Mansur Ali Jisan*
>> Ph.D. Student
>> URI Graduate School of Oceanography, RI 02882
>>
>> <hasancee at iut-dhaka.edu>
>> _______________________________________________
>> ncl-talk mailing list
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>>
>
--
*Mansur Ali Jisan*
Ph.D. Student
URI Graduate School of Oceanography, RI 02882
http://jisan-mansur.com/
<hasancee at iut-dhaka.edu>
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