[ncl-talk] Plotting Lat/Lon Points on a map

Tim Melino melino33 at gmail.com
Sat May 27 07:20:21 MDT 2017


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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