[ncl-talk] Trying to plot streamlines using WRF data, streamlines are not in the correct part of the plot
Craig Tierney - NOAA Affiliate
craig.tierney at noaa.gov
Thu Apr 16 14:51:34 MDT 2015
Mary,
Thanks for your help on this. I was at a conference since I sent in my
help requests and hadn't had time to look at all of this. After installing
NCL 6.3 and changing my script to use gsn_csn_streamline_scalar_map, I was
able to get the plot I expected.
Thanks,
Craig
On Thu, Apr 9, 2015 at 10:51 PM, Mary Haley <haley at ucar.edu> wrote:
> Hi Craig,
>
> You are using the generic "gsn_streamline_scalar_map" function, which
> doesn't look for the special lat2d/lon2d attributes.
>
> If you have NCL V6.3.0 installed, then you can use
> gsn_csm_streamline_scalar_map, which should recognize these special
> attributes.
>
> I created a simple example for you. See example wrf_gsn_8.ncl at:
>
> http://www.ncl.ucar.edu/Applications/wrfgsn.shtml#ex8
>
> --Mary
>
> On Thu, Apr 9, 2015 at 3:17 PM, Craig Tierney - NOAA Affiliate <
> craig.tierney at noaa.gov> wrote:
>
>> Hello,
>>
>> After some good help from some list members, I believe that I am setting
>> up the resources for plotting WRF data without the WRF functions.
>> However, I still get no streamlines in my plot, or at least not in the
>> correct place.
>>
>> I am using NCL 6.1.2. My WRF domain is close to CONUS. The domain is
>> LambertConformal and I am setting the mapping properties stored in the
>> Global section of the NetCDF file to the appropriate variables for the LC
>> mapping. To draw the streamlines, I am basing my code off of the example
>> here:
>>
>> https://www.ncl.ucar.edu/Applications/Scripts/gsn_stream_4.ncl
>>
>> I read in the data, massage it, then try and plot it. When I plot the
>> speed, u1, or v1 arrays with contour:
>>
>> contour = gsn_csm_contour_map(wks,speed,res)
>>
>> I get what I would want, a contour of that variable with the bounds of
>> the plot that of my domain. When I try the same thing to create a
>> streamline plot:
>>
>> plot = gsn_streamline_scalar_map(wks,u1,v1,speed,res)
>>
>> I get nothing. When I remove setting the Corners of the domain by
>> commenting out the following:
>>
>> res at mpRightCornerLatF = lat2d(0,0)
>> res at mpRightCornerLonF = lon2d(0,0)
>> res at mpLeftCornerLatF = lat2d(nlat-1,nlon-1)
>> res at mpLeftCornerLonF = lon2d(nlat-1,nlon-1)
>> res at mpLimitMode = "Corners"
>>
>> I get streamlines, but they are between 0E and 225E and 0N to 90N. For
>> the CONUS domain I am using the corners are about (138W,21N) and
>> (298W,47N). Something is being calculated, but not what I was expecting.
>>
>> Any ideas are appreciated.
>>
>> Thanks,
>> Craig
>>
>> 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.
>> dir =
>> "/scratch2/portfolios/BMC/winds/Craig.Tierney/theia/wrf/windswrf/trunk/conusplus-wrf-6day/201308010000/nowfp-nocu/wrf/"
>> filename = "wrfout_d01_2013-08-04_00:00:00"
>> a = addfile(dir + filename + ".nc","r")
>>
>> ;---Read terrain height and lat/lon off file.
>> it = 0 ; first time step
>> du1 = wrf_user_getvar(a,"U10",it) ; Terrain elevation
>> dv1 = wrf_user_getvar(a,"V10",it) ; Terrain elevation
>> dlon2d=wrf_user_getvar(a,"XLONG",it)
>> dlat2d=wrf_user_getvar(a,"XLAT",it)
>>
>> ; Down sample hack
>> d=dimsizes(du1)
>> nx=d(0)
>> ny=d(1)
>> s=8
>> u1=du1(0:nx-1:s,0:ny-1:s)
>> v1=dv1(0:nx-1:s,0:ny-1:s)
>> lat2d=dlat2d(0:nx-1:s,0:ny-1:s)
>> lon2d=dlon2d(0:nx-1:s,0:ny-1:s)
>>
>> u1 at lon2d=lon2d
>> u1 at lat2d=lat2d
>> v1 at lon2d=lon2d
>> v1 at lat2d=lat2d
>>
>> speed=sqrt(u1*u1+v1*v1)
>> speed at lat2d=lat2d
>> speed at lon2d=lon2d
>>
>> wks = gsn_open_wks("png","wrf_gsn")
>>
>> ;---Set some basic plot options
>> res = True
>>
>> res at gsnMaximize = True ; maximize plot in frame
>>
>> res at tiMainString = filename
>>
>> ;res at mpProjection = "CylindricalEquidistant"
>> res at mpProjection = "LambertConformal"
>>
>> res at mpLambertParallel1F = a at TRUELAT1 ; two parallels
>> res at mpLambertParallel2F = a at TRUELAT2
>> res at mpLambertMeridianF = a at STAND_LON ; central meridian
>> res at mpCenterLonF = a at CEN_LON
>> res at mpCenterLatF = a at CEN_LAT
>>
>> d=dimsizes(u1)
>> nlat=d(0)
>> nlon=d(1)
>>
>> ;;;; Comment this section out, and we get streamlines, but in the wrong
>> place
>> ;;;; This is why they don't show up in the zoomed in plot
>> ; res at mpRightCornerLatF = lat2d(0,0)
>> ; res at mpRightCornerLonF = lon2d(0,0)
>> ; res at mpLeftCornerLatF = lat2d(nlat-1,nlon-1)
>> ; res at mpLeftCornerLonF = lon2d(nlat-1,nlon-1)
>> ; res at mpLimitMode = "Corners"
>>
>> ;---Additional resources desired
>> res at pmTickMarkDisplayMode = "Always" ; nicer tickmarks
>>
>> res at mpDataBaseVersion = "MediumRes" ; better and more map
>> outlines
>> res at mpDataSetName = "Earth..4"
>> res at mpOutlineBoundarySets = "AllBoundaries"
>> res at mpOutlineOn = True
>>
>> res at lbOrientation = "Vertical"
>> res at tiMainOffsetYF = -0.03 ; Move the title down
>>
>> ;; This is where we decide what to plot
>> ptype="contour"
>> ; ptype="streamline"
>>
>> if (ptype .eq. "contour") then
>> print("Plotting: "+ptype)
>> res at cnFillOn = True
>> res at cnFillPalette = "OceanLakeLandSnow"
>> res at cnLinesOn = False
>> ;contour = gsn_csm_contour_map(wks,speed,res)
>> ;contour = gsn_csm_contour_map(wks,u1,res)
>> contour = gsn_csm_contour_map(wks,v1,res)
>> else
>> if (ptype .eq. "streamline") then
>> print("Plotting: "+ptype)
>> res at pmTickMarkDisplayMode = "Always"
>> res at pmLabelBarDisplayMode = "Always"
>> res at pmLabelBarOrthogonalPosF = -0.02
>> res at pmLabelBarWidthF = 0.1
>> res at lbPerimOn = False
>>
>> plot = gsn_streamline_scalar_map(wks,u1,v1,speed,res)
>> else
>> print("Unable to plot either contour or streamline: "+ptype)
>> exit
>> end if
>> end if
>>
>> end
>>
>>
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>>
>
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