[ncl-talk] Plotting Lat/Lon Points on a map
Barry Lynn
barry.h.lynn at gmail.com
Sat May 27 22:48:37 MDT 2017
Hi:
When the data is skewed, it is often because the projection you're reading
is not the one your plotting.
Do you know the projection of the data you're using?
If you print(a) where a is the file you specify from addfile, you can see
the variables (and hopefully projection) indicated within.
Barry
On Sat, May 27, 2017 at 4:20 PM, Tim Melino <melino33 at gmail.com> wrote:
> Hi,
>
> I am attempting to plot a subset of the MRMS data from NCEP. The latitude
> and longitude I am plotting is :
>
> LAT: 36.5459089
> LON: -79.4585847
>
> I attached an image of the output along with the grib file I am using for
> input. I am noticing a couple things first the data appears to be skewed,
> so I am not sure if it is an issue with the map projection. Second the
> point which should be plotted in Virginia is actually plotted in North
> Carolina, the only thing that I have been able to do if offset the marker
> to compensate for the issue. Does anyone have any ideas on how to fix these
> issues? Any ideas would be greatly appreciated!
>
> Thanks!
> Tim
>
> Code:
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>
> begin
>
> lati=LAT
> loni=LON
> date=DATE
> address=ADDRESS
>
>
> ; Convert the Lat/Lon to a Float
> latc= stringtofloat(lati)
> lonc = stringtofloat(loni)
>
> ; Set the Map Bounds
> minlat = latc - .12
> maxlat = latc + .12
> minlon = lonc - .15
> maxlon = lonc + .15
>
>
> ;========================
> ; get list of all files and open as "one big file"
> ;========================
> a = addfile( "./" + lati + "_" + loni + ".grib2","r")
>
> type = "png"
> wks = gsn_open_wks(type,"./" + lati + "" + loni + ".png")
>
> ; Set some Basic Plot options
> res = True
> res at gsnDraw = False ; do not draw the plot
> res at gsnFrame = False ; do not advance the frame
> pltres = True
> pltres at NoTitles = True
> pltres at CommonTitle = True
> pltres at PlotTitle = ""
> pltres at PanelPlot = True
> pltres at FramePlot = False
>
> ; Set the Colormap
> gsn_define_colormap(wks,"hail")
> lat = a->lat_0
> lon = a->lon_0
> water = a->VAR_209_3_34_P0_L102_GLL0(:,:)
> hail = water *0.0393701;
>
>
> ; Plotting options for Hail
> res at gsnMaximize = True
> res at mpGeophysicalLineThicknessF = 4.0
> ;res at mpProjection = "LambertConformal"
> res at mpGridLineThicknessF = 0.5
> res at mpLimbLineThicknessF = 4.0
> res at mpNationalLineThicknessF = 4.0
> res at mpUSStateLineThicknessF = 4.0
> res at mpProvincialLineThicknessF = 4.0
> res at mpOutlineBoundarySets = "AllBoundaries"
> res at mpDataBaseVersion = "Ncarg4_1"
> res at mpDataSetName = "Earth..4"
> res at mpFillOn = False ; fill continents
> res at mpPerimOn = False ; no box around map
> res at tiMainOn = True
> res at tiMainFontColor = "Black"
> res at tiMainString =""
> res at tiXAxisString = ""
> res at tiYAxisString = ""
> res at gsnLeftString = "Date: " + date ; add the gsn titles
> res at gsnRightString = ""
> res at gsnStringFontHeightF = 0.016
> res at cnInfoLabelOrthogonalPosF = 0.07 ; offset second label information
> res at gsnContourLineThicknessesScale = 0.001
> res at cnFillOn = True
> res at lbTitleOn = True ; remove field
> name from label bar
>
> ; Set the Map Bounds
> res at sfYArray = lat
> res at sfXArray = lon
> res at mpLimitMode = "LatLon"
> res at mpMinLatF = minlat
> res at mpMaxLatF = maxlat
> res at mpMinLonF = minlon
> res at mpMaxLonF = maxlon
> res at tmXBOn = False
> res at tmYLOn = False
> res at tmXTOn = False
> res at tmYROn = False
> res at gsnAddCyclic = False
> res at tfDoNDCOverlay = False ; do not
> transform data
> res at cnLevelSelectionMode = "ExplicitLevels" ; set explicit
> contour levels
> res at cnLevels = (/ 0.5,0.75, 1.00, 1.25, 1.50, 1.75, 2.00,
> 2.50, 3.00, 3.50, 4.00, 4.50, 5.00/) ; set levels
> res at tiMainFontHeightF = 0.018 ; font height of
> title
> res at lbAutoManage = False ; we control label
> bar
> res at pmLabelBarDisplayMode = "Always" ; turns on label bar
> res at lbOrientation = "Horizontal" ; ncl default is
> vertical
> res at pmLabelBarSide = "Bottom" ; default is right
> res at lbLabelStride = 1 ; skip every other
> label
> res at pmLabelBarWidthF = 0.7 ; default is shorter
> res at pmLabelBarHeightF = 0.1 ; default is taller
> res at lbLabelFontHeightF = .012 ; default is HUGE
> res at lbPerimOn = False ; default has box
> res at lbTitleString = "Hail Size (Inches)"
> res at lbTitleFontHeightF = 0.012
> plot = gsn_csm_contour_map(wks,hail,res)
>
> ; Setup the point
> mstring1 = "z"
> fontnum1 = 35
> xoffset1 = .4
> yoffset1 = .7
> ratio1 = 0.0
> size1 = 1.0
> angle1 = 0.0
>
> Tm_index = NhlNewMarker(wks, mstring1, fontnum1, xoffset1, yoffset1,
> ratio1, size1, angle1)
>
> ; Plot the sites and label them
> gres = True
> gres at gsMarkerIndex = Tm_index ; 16
> gres at gsMarkerSizeF = 0.015 ; .009
> gres at gsMarkerColor = "black"
> gres at txFont ="helvetica-bold"
> gres at txFontHeightF = "25"
>
> site = (/address/)
> lats = (/latc/)
> lons = (/lonc/)
>
> dot = gsn_add_polymarker(wks,plot,lons,lats,gres)
> tlats =lats + .03
> tlons =lons
> text = gsn_add_text(wks,plot,site,tlons,tlats ,gres)
>
> ; Draw the graphics
> draw(plot)
> frame(wks)
>
> end
>
>
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--
Barry H. Lynn, Ph.D
Senior Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
Givat Ram, Jerusalem 91904, Israel
Tel: 972 547 231 170
Fax: (972)-25662581
C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525
US 914 432 3108
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