Re: projection squeezing

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Sat Jan 08 2011 - 12:27:36 MST

The file dump says that only grid defined in the file is a standard lat-lon grid (Cylindrical Equidistant Projection Grid -- GRIB GDS grid type 0) not a rotated grid. However the plot definitely looked like rotation was involved. If you can upload the data file to our ftp server we could look into this further. (Instructions at http://www.ncl.ucar.edu/report_bug.shtml if you need them.)
 -dave

On Jan 8, 2011, at 12:18 AM, ahmed lasheen wrote:

> Hello
> i haven't found those two attributes in the grib file .i have attached the output of the ncl_filedump in the mail. but i found these two attributes in the WPS(wrf preprocessing )
> POLE_LAT : 90
> POLE_LON : 0
> and when i used them in the scripts nothing changed.
> thanks in advance
>
> On Fri, Jan 7, 2011 at 8:38 PM, David Brown <dbrown@ucar.edu> wrote:
> Hi Ahmed,
>
> You need to specify the center lat and lon (mpCenterLatF and mpCenterLonF). You can get the correct values from the coordinate attributes 'Latitude_of_southern_pole' and 'Longitude_of southern_pole' in the grib file. Add 90 to the latitude value and use the longitude as is to get the projection center. Also you may need to set pmTickMarkDisplayMode to "always" to get the correct tickmarks and labels.
> -dave
>
> On Jan 7, 2011, at 9:45 AM, ahmed lasheen wrote:
>
>> Hello
>> I am trying to plot a rotated lat lon grib file , but at southeast and south the image is squeezed , i have used the native grid and also the corner resource limit mode to adjust the corners but the problem still exist.
>>
>> the code and the output are attached .
>>
>> 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.
>> dir = "../../../data/wrf_10111200/"
>> f1 = addfile(dir + "10121100.GrbF153.grb","r") ;opening the file
>> geo = f1->HGT_GDS0_ISBL_10(:,:,:) ;reading the geopotential height at all levels(gpm)
>> t = f1->TMP_GDS0_ISBL_10(:,:,:) ;reading the temperature at all levels (K)
>> u = f1->U_GRD_GDS0_ISBL_10(:,:,:) ;reading the u-wind at all levels (m/s^2)
>> v = f1->V_GRD_GDS0_ISBL_10(:,:,:) ;reading the v-wind at all levels (m/s^2)
>> lat = f1->g0_lat_0(:) ;reading the latitude
>> lon = f1->g0_lon_1(:) ;reading the longitude
>> lev = f1->lv_ISBL3(:)
>>
>> t=t-273.15 ;Converting from kelvin to celsius
>> ;*************printing some information***************************
>> ;print("these are the levels")
>> ;print(lev)
>> print ("at level "+lev(9)+"mb==> min(T)="+min(t(9,:,:))+", max(T)="+max(t(9,:,:)) )
>> ;************opening the workstation*******************************
>> wks = gsn_open_wks("png" ,"../output/upper") ; ps,pdf,x11,ncgm,eps
>> gsn_define_colormap(wks,"BlueRed") ; choose color map
>> ;gsn_reverse_colormap(wks)
>> ;gsn_draw_colormap(wks)
>> ;**************************************************************
>> ;************************************************************
>> ;=========>>>>>>>gsn_csm_map
>> resm = True
>> resm@tfDoNDCOverlay = True ; do not transform data(native grid)
>> resm@mpProjection = "CylindricalEquidistant"
>> resm@mpLimitMode = "Corners"
>> resm@mpLeftCornerLatF = min(lat)
>> resm@mpLeftCornerLonF = min(lon)
>> resm@mpRightCornerLatF = max(lat)
>> resm@mpRightCornerLonF = max(lon)
>> resm@mpOutlineOn = True ; enables the map area outline
>> resm@mpOutlineBoundarySets = "AllBoundaries" ; turn on country boundaries
>> resm@mpGeophysicalLineColor = "black" ;color of cont. outlines
>> resm@mpGeophysicalLineThicknessF = 1. ;double the thickness of geophysical boundaries
>> resm@mpNationalLineThicknessF = 1. ;double the thickness of national boundaries
>> resm@mpFillOn = False
>> ;resm@vpWidthF = 1.0 ;width of the image
>> ;resm@vpHeightF = 1.0 ;Height of the image
>> ;resm@mpGridAndLimbOn =True
>> resm@gsnDraw = False ;do not draw the plot
>> resm@gsnFrame = False ;do not advance the frame
>> plot_m = gsn_csm_map(wks,resm)
>> ;************************************************************
>> ;***********************************************************
>> ;========>>>>>>gsn_csm_contour geopotential height
>> resc = True
>> resc@cnMaxLevelValF = max(geo(9,:,:))
>> resc@cnMinLevelValF = min(geo(9,:,:))
>> ;;;;Line or shaded contour
>> resc@cnFillOn = False
>> resc@cnLinesOn = True
>> ;;;;;properties of the lines
>> resc@cnLineThicknessF = 1
>> resc@cnLineColor = "black"
>> ;;;;;Titles
>> resc@tiMainFont ="triplex_italic"
>> resc@gsnStringFont ="triplex_italic"
>> resc@gsnRightString = geo@units ;right string
>> resc@gsnLeftString = geo@long_name ;left string
>> resc@gsnCenterString = ""
>> resc@gsnLeftStringOrthogonalPosF = 0.1 ;left string vertical pos
>> resc@gsnRightStringOrthogonalPosF = 0.1 ;right string vertical pos
>> ;;;;;infolabel
>> resc@cnInfoLabelString = "MSL contours from $CMN$ to $CMX$ by $CIU$"
>> resc@cnInfoLabelFontColor = "black" ;;red font color
>> resc@cnInfoLabelPerimOn = False ;;not to draw abox arount information bar
>> resc@cnInfoLabelParallelPosF = 1.0 ;;position in x axis
>> resc@cnInfoLabelOrthogonalPosF = 0.1 ;;position in y axis
>> resc@cnInfoLabelFont = "triplex_italic"
>> resc@cnInfoLabelFontAspectF = 2
>> resc@cnInfoLabelFontHeightF = 0.012
>> ;;;;;LineLabel
>> resc@cnLabelMasking = True ;; not to overlay the label and contour line
>> resc@cnLineLabelAngleF = 0.0;make the labelline label horizontal
>> resc@cnLineLabelFontColor = "black"
>> resc@cnLineLabelPerimOn = True ;; draw box around the label
>> resc@cnLineLabelFont = "triplex_italic"
>> resc@cnLineLabelFontAspectF = 2
>> resc@cnLineLabelFontHeightF = 0.011
>>
>> ;;;;;Donot draw know
>> resc@gsnDraw = False ; do not draw the plot
>> resc@gsnFrame = False ; do not advance the frame
>> plot_c=gsn_csm_contour(wks,geo(9,:,:),resc)
>> ;******************************************************************
>> ;=======>>>>>>gsn_csm_contour Temperature
>> rest = True
>> ;;;;Line or shaded contour
>> rest@cnFillOn = True
>> rest@cnLinesOn = False
>> ;;;;spreading the color
>> rest@gsnSpreadColors = True
>> ;;;;;Titles
>> rest@tiMainFont ="triplex_italic"
>> rest@gsnStringFont ="triplex_italic"
>> rest@gsnRightString = "C" ;right string
>> rest@gsnLeftString = t@long_name ;left string
>> rest@gsnCenterString = ""
>> rest@gsnLeftStringOrthogonalPosF = 0.05 ;left string vertical pos
>> rest@gsnRightStringOrthogonalPosF = 0.05 ;right string vertical pos
>> ;;;;label bar
>> rest@lbLabelsOn = True
>> rest@lbLabelStride = 2
>> rest@lbLabelFont = "triplex_italic"
>> rest@lbLabelFontAspectF = 2
>> rest@lbLabelFontHeightF = 0.01
>> rest@lbTopMarginF = 0.7
>> rest@lbTitleOn = True
>> rest@lbTitleFont = "triplex_italic"
>> rest@lbTitleString = "Temperature in Celsius"
>> rest@lbTitleFontAspectF = 2
>> rest@lbTitleFontHeightF = 0.01
>> ;;Donot draw know
>> rest@gsnDraw = False ; do not draw the plot
>> rest@gsnFrame = False ; do not advance the frame
>> plot_t=gsn_csm_contour(wks,t(9,:,:),rest)
>> ;******************************************************************
>> ;======>>>>>>> overlay all plots
>> overlay(plot_m,plot_t) ;; put the line contor(geopotential height) first
>> overlay(plot_m,plot_c) ;; put the shaded contour(the temperature) second
>> draw(plot_m)
>> frame(wks)
>>
>> end
>>
>> --
>> ===============
>> Ahmed Lasheen
>> Junior researcher at Cairo Numerical Weather Prediction Center (CNWPC)
>> Egyptian Meteorological Authority(EMA)
>> Cairo,Egypt
>> ===============
>>
>> <upper.000001.png><upper_air.ncl>_______________________________________________
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>
>
>
>
> --
> ===============
> Ahmed Lasheen
> Junior researcher at Cairo Numerical Weather Prediction Center (CNWPC)
> Egyptian Meteorological Authority(EMA)
> Cairo,Egypt
> ===============
>
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Received on Sat Jan 8 12:27:45 2011

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