Re: map shifting

From: Mary Haley <haley_at_nyahnyahspammersnyahnyah>
Date: Thu Jan 06 2011 - 10:10:02 MST

Ahmed,

Thanks for providing your file.

In order to do an overlay of contours on a map with tfDoNDCOverlay set to True, you must have the
*exact* map projection that the data are on. I think the reason why you are seeing the shift is partly
because you don't have the correct projection.

You can get around this problem by not setting tfDoNDCOverlay to True, and instead using your
lat2d/lon2d values to get your projection correct.

Also, instead of using mpMin/MaxLat/LonF resources, I would use mpRight/LeftCornerLat/LonF resources
with an "mpLimitMode" set to "corners"

Finally, you don't need to hard-code the values for mpCenterLatF and mpCenterLonF. Since they are
provided on your file, you can set them by referencing the CEN_LAT and CEN_LON global attributes:

  res@mpCenterLatF = a@CEN_LAT
  res@mpCenterLonF = a@CEN_LON

Please see the attached modified script and image.

--Mary

On Jan 6, 2011, at 1:46 AM, ahmed lasheen wrote:

> Hello
> I have uploaded the data file to the ftp server. about the center values
> i got them from the wrf namelist ref_lat and ref_lon which indicate the center in which the domain is rotated.
> thanks in advance
> ahmed
>
> On Wed, Jan 5, 2011 at 1:41 PM, David Brown <dbrown@ucar.edu> wrote:
> Hi Ahmed,
>
> Where did you get the values for the center lat and lon? Are they part of the metadata for the file? It would help if you can upload your data file to our ftp server. See the directions at
> http://www.ncl.ucar.edu/report_bug.shtml. Thanks,
> -dave
>
>
> On Jan 5, 2011, at 10:44 AM, ahmed lasheen wrote:
>
>> Hello
>> I trying to plot the terrain of the NMM-WRF ,but the map is being shifted from the terrain (or reverse) , the projection of data is rotated lat lon .
>> i have used the CylindricalEquidistant projection ,as i read from the ncl-talk archive that is like the rotated lat lon.
>> here is the code i wrote
>>
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>> ;******************************************************
>> begin
>> ;****************** Open file and get variables *************
>> a = addfile("../../data/wrf_10111200//geo_nmm_nest.l01.nc","r")
>> ter = a->HGT_M (0,:,:)
>> lat2d = a->XLAT_M (0,:,:)
>> lon2d = a->XLONG_M(0,:,:)
>> ;*******************make the graphics ***********************
>> wks = gsn_open_wks("pdf" ,"terrain") ; ps,pdf,x11,ncgm,eps
>> gsn_define_colormap(wks,"gui_default") ; select color map
>>
>> res = True ; plot mods desired
>> res@cnFillOn = True ; turn on color
>> res@cnLinesOn = False ; turn contour lines
>> res@mpMaxLatF = max(lat2d)
>> res@mpMinLatF = min(lat2d)
>> res@mpMaxLonF = max(lon2d)
>> res@mpMinLonF = min(lon2d)
>> res@gsnSpreadColors = True
>> res@lbLabelStride = 2
>> res@mpLimitMode = "latlon" ; use lat/lon coordinates to limit area
>> res@mpProjection = "CylindricalEquidistant"
>> res@mpGreatCircleLinesOn = True
>> res@gsnCenterString = res@mpProjection+" Projection"
>> res@tfDoNDCOverlay = True
>> res@mpOutlineBoundarySets = "National"
>> res@mpCenterLatF = 37
>> res@mpCenterLonF = 22
>> plot = gsn_csm_contour_map_ce(wks,ter(:,:),res)
>> end
>>
>> thanks in advance
>>
>> --
>> ===============
>> Ahmed Lasheen
>> Egyptian Meteorological Authority(EMA)
>> Cairo,Egypt
>> ===============
>>
>> _______________________________________________
>> ncl-talk mailing list
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>
>
>
> --
> ===============
> Ahmed Lasheen
> Egyptian Meteorological Authority(EMA)
> Cairo,Egypt
> ===============
>
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> ncl-talk mailing list
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> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

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Received on Thu Jan 6 10:10:11 2011

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