[ncl-talk] overlaying map on WRF region
Mary Haley
haley at ucar.edu
Thu Oct 8 11:32:00 MDT 2015
I think the issue may be with the resolution of the map outlines, and not
with the map projection.
Dennis provided me with your sample WRF output file, and I created a script
that shows three plots, each with different map resolutions:
- the "MediumRes" one (the one you are currently using)
- "HighRes" (a high-res coastal outline that you have to download; see
http://www.ncl.ucar.edu/Document/Graphics/rangs.shtml)
- Using shapefile outlines downloaded from gadm.org/country
See the attached script, and the final image from this script, which draws
all three plots in a panel so you can see the difference.
If you run this script, you will also see a frame that draws the actual WRF
lat/lon grid. This helps you see that the map projection on the file is
correct, because your WRF lat/lon lines would be crooked if not.
The medium resolution map database, which is part of NCL, is not as
accurate as the RANGS or shapefile databases.
--Mary
On Thu, Oct 8, 2015 at 4:30 AM, <Solange.Fermepin at lmd.jussieu.fr> wrote:
> Hi Mary,
>
> thank you for your answer.
>
> I was aware that I used a mix of things, but in the end it was the script
> that gave better solutions.
>
> I tried your way, without using any WRF specifics, but I still got the map
> shifted (see the attached new figure).
>
> As Dave suggested, this is probably a more 'WRF-help' problem, so I will
> write to that list.
>
> Thanks again!
>
> All the best,
> Solange
>
> > It looks like you are trying to mix and match the use of
> wrf_map_overlays,
> > wrf_map_resources, and overlay. Also, you have a "map_res" variable which
> > never gets used and is not needed for anything, so all references to it
> > should be removed.
> >
> > Since you are calling wrf_map_resources and overlay, you don't need to
> > call
> > wrf_map_overlays, because it actually calls wrf_map_resources and overlay
> > under the hood
> >
> > Really, though, you should just use gsn_csm_contour_map, so you don't
> have
> > to do the overlay yourself.
> >
> > I think you can replace all the code after you read in tc2 with the
> > following code (UNTESTED):
> >
> > res = True
> > res at cnFillOn = True
> > res at cnLinesOn = False
> > res at cnLevelSelectionMode = "ExplicitLevels"
> > res at cnLevels = (/
> > 0.,2.,4,5,6,7,8,9,10,11,12,13,14,15,20/)
> > res at lbLabelStride = 1.
> > res at lbLabelFontHeightF = 0.015
> > res at lbOrientation = "Horizontal"
> > res at pmLabelBarOrthogonalPosF = -0.005
> >
> > res at tiMainString = "2 m Temperature - "+date
> > res at gsnLeftString = "Temperature (" + tc2 at units + ")"
> > res at gsnRightString = ""
> >
> > res = wrf_map_resources(a,mpres)
> > res at gsnAddCyclic = False
> > res at tfDoNDCOverlay = True
> >
> > plot = gsn_csm_contour_map(wks,tc2,res)
> >
> > Note that I only have one resource list, and that I'm calling
> > gsn_csm_contour_map, which calls "overlay" for me.
> >
> > --Mary
> >
> >
> >
> > On Wed, Oct 7, 2015 at 4:17 PM, <Solange.Fermepin at lmd.jussieu.fr> wrote:
> >
> >> Hello everybody!
> >>
> >> I am using NCL to plot fields from a WRF simulation. I am having
> >> problems
> >> overlaying the map on the contour plot: the boundary of the country is
> >> not
> >> right placed (I checked with ferret).
> >>
> >> I think there might be a projection problem, even though the function
> >> wrf_map_resources gets the right projection (mercator in this case).
> >>
> >> I am lost. If anybody has any ideas, I will be really grateful.
> >>
> >> Below there is my script and I have also attached the figure so you get
> >> an
> >> idea. For instante, see the problem at around 0.5W:45.5N).
> >>
> >> Thanks a lot!
> >> Solange
> >>
> >> ;----------------------------------------------------------------------
> >> ; NCL script to plot fields from a WRF simulation
> >> ;----------------------------------------------------------------------
> >> 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/wrf/WRFUserARW.ncl"
> >> ;----------------------------------------------------------------------
> >> begin
> >> ;---Open WRF output file
> >> frun
> >>
> >>
> ="/home/sfermepin/WRF/SNCF/FR2/RUNS/mpWSM3-raRRTM-blYSU-cuKF/20141023_00/wrfout_d01_2014-10-23_00:00:00"
> >> a = addfile(frun,"r")
> >> date="20141023"
> >> dom="03"
> >> ;---Read several WRF variables at first time step
> >> it = 0 ; first record
> >> tc2 = wrf_user_getvar(a,"T2",5);
> >> tc2 = tc2-273.15
> >>
> >> ;---Change the metadata
> >> tc2 at description = "2m Temperature"
> >> tc2 at units = "degC"
> >>
> >> ;---Set common resources for all plots
> >> res = True
> >> res at gsnFrame = False
> >> res at gsnDraw = False
> >> res at gsnLeftString = ""
> >> res at gsnRightString = ""
> >>
> >> ;---Necessary for contours to be overlaid correctly on WRF projection
> >> res at tfDoNDCOverlay = True
> >>
> >> ;---Overlay plots on map and draw.
> >> pltres = True
> >> pltres at gsnFrame = False
> >> pltres at gsnDraw = False
> >>
> >> mpres = True
> >> mpres at gsnFrame = False
> >> mpres at gsnDraw = False
> >> mpres at mpGeophysicalLineColor = "black"
> >> mpres at mpLimitMode = "Corners"
> >> mpres = wrf_map_resources(a,mpres)
> >>
> >> ;---Map plot
> >> map_res = True
> >> map_res at gsnFrame = False
> >> map_res at gsnDraw = False
> >>
> >> ; Output file: temp
> >> wks = gsn_open_wks("pdf","try")
> >> gsn_define_colormap(wks,"precip2_17lev")
> >> ;---Temperature filled contour plot
> >> tc_res = res
> >> tc_res at cnFillOn = True
> >> tc_res at cnLinesOn = False
> >> tc_res at cnLevelSelectionMode = "ExplicitLevels"
> >> tc_res at cnLevels = (/
> >> 0.,2.,4,5,6,7,8,9,10,11,12,13,14,15,20/)
> >> ;tc_res at cnLevels = (/
> >> 0.,1.,2.,2.5,5.,6.,7.,8.,09.,10.,11.,12.,13.,14.,15.,16.,20./)
> >> tc_res at lbLabelStride = 1.
> >> tc_res at lbLabelFontHeightF = 0.015
> >> tc_res at lbOrientation = "Horizontal"
> >> tc_res at pmLabelBarOrthogonalPosF = -0.005
> >> tc_res at gsnLeftString = "Temperature (" + tc2 at units + ")"
> >> tc_res at gsnAddCyclic = False
> >>
> >> mpres at tiMainString = "2 m Temperature - "+date
> >>
> >> contour_tc = gsn_csm_contour(wks,tc2,tc_res)
> >> plot = wrf_map_overlays(a,wks,(/contour_tc/),pltres,mpres)
> >> overlay(plot,contour_tc)
> >> draw(plot) ; This will draw all overlaid plots and the map
> >> frame(wks)
> >> end
> >>
> >>
> >> --
> >> Solange Fermepin, PhD
> >> Laboratoire de Météorologie Dynamique - CNRS/IPSL
> >> Tour 45-55, 3ème étage
> >> 4 place Jussieu
> >> 75252 Paris cedex 05
> >> France
> >>
> >> Tel: +33 (0) 1 44 27 52 55
> >> E-mail: solange.fermepin at lmd.jussieu.fr
> >> _______________________________________________
> >> ncl-talk mailing list
> >> ncl-talk at ucar.edu
> >> List instructions, subscriber options, unsubscribe:
> >> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
> >>
> >>
> >
>
>
> --
> Solange Fermepin, PhD
> Laboratoire de Météorologie Dynamique - CNRS/IPSL
> Tour 45-55, 3ème étage
> 4 place Jussieu
> 75252 Paris cedex 05
> France
>
> Tel: +33 (0) 1 44 27 52 55
> E-mail: solange.fermepin at lmd.jussieu.fr
>
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