[ncl-talk] map question

[Dave Allured - NOAA Affiliate]

It looks like NCL example topo_4 does what you want.  Here is my suggestion
for debugging.  Start with the original code for example topo_4.  Change
only one thing at a time, moving toward your code version, until you find
something that causes the unwanted perimeter lines.  Change that back to
original.  Then continue stepping through all the rest of your changes
until you have a reduced set of changes that causes the perimeter lines.

In this way, you will reduce the problem to something that is easier to
understand.


On Mon, Oct 16, 2023 at 9:35 AM lzl lai via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> I have a problem deleting those thin lines in my map (the red arrow
> pointed area)
> . Could you please help me to remove them? Thanks a lot!
>
> I use "ETOPO_2022_v1_60s_N90W180_bed.nc"  ,for drawing topography,
> and "gadm41_TWN_0.shp" , for drawing coastline in Taiwan
> and also set res at cnMissingValPerimOn = False
>
> my scrip is below :
> ========================================
> ;---Read data
> ;  topo_file = "../topo/ETOPO_2022_v1_60s_N90W180_geoid.nc"
>   topo_file = "../topo/ETOPO_2022_v1_60s_N90W180_bed.nc"
>   f  = addfile(topo_file,"r")
>   elev  = f->z
> ;
> ; Set all values below -100 to missing, hence removing all
> ; the ocean elevation values. The ocean will be filled in
> ; a light blue (see mpOceanFillColor below).
> ;
>   elev = where(elev.lt.-100.,elev at _FillValue,elev)
>
> ;;file --- 2
>   shpdir = "/home/lzl/data2/lzl/CWBtrend/topo/TW/"
>   filename ="gadm41_TWN_0.shp"
> ;----plot-----------------------------------------------------
>   wks = gsn_open_wks("pdf","./pic/TW_topo")           ; send graphics to
> PNG file
>   gsn_define_colormap(wks,"WhiteBlueGreenYellowRed")
>
>   res                    = True
>   res at gsnMaximize        = True     ; maximize plot in frame
>
>   res at cnFillOn           = True     ; turn on contour fill
>   res at cnLinesOn          = False    ; turn off contour lines
>   res at cnLineLabelsOn     = False    ; turn off line labels
>   res at cnInfoLabelOn      = False    ; turn off info label
>   res at lbBoxLinesOn       = False    ; turn off labelbar box lines
>   res at cnFillMode         = "MeshFill"   ; for faster draw
>
>  res at cnLevelSelectionMode = "ManualLevels"
>   res at cnMinLevelValF       = 100.
>   res at cnMaxLevelValF       = 3600.
>   res at cnLevelSpacingF      = 200.
>   res at cnMissingValPerimOn = False
>   res at cnMissingValPerimGridBoundOn =False
>   res at gsnAddCyclic         = False           ; don't add longitude cyclic
> point
>
> ;---color bar----
>   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      = 0.5               ; default is shorter
>   res at pmLabelBarHeightF     = 0.1               ; default is taller
>   res at lbLabelFontHeightF    = .018              ; default is HUGE
>   res at lbPerimOn             = False             ; default has box
>   res at lbBoxLinesOn       =   True  ; turn on labelbar box lines
>   res at lbBoxEndCapStyle = "TriangleBothEnds"
>
> ;---Zoom in on map
>   res at mpLimitMode           = "LatLon"
>   res at mpMinLatF            = 21.5
>   res at mpMaxLatF            = 25.5
>   res at mpMinLonF            = 119.5
>   res at mpMaxLonF            = 122.5
>
>   res at mpFillOn             = True
>   res at mpGeophysicalLineColor      = "transparent"       ; color of cont.
> outlines
>   res at mpOceanFillColor     = "transparent"
>   res at mpLandFillColor      = "transparent"
>
>   res at mpFillDrawOrder      = "PostDraw"
>   res at mpDataBaseVersion = "MediumRes"
>
>   res at mpOutlineOn           = False
>   res at pmTickMarkDisplayMode       = "Always"
>   res at mpGeophysicalLineThicknessF = 2
>   plot = gsn_csm_contour_map(wks,elev,res)
>
>   nres                  = True
>   lnres at gsLineColor = "black"
>   lnres at gsLineThicknessF = 2.0
>   dum  = gsn_add_shapefile_polylines(wks,plot,shpdir+filename,lnres)
> ;---Generate random lat/lon locations and dummy text strings
>   lont  = (/121.513,120.684,120.197,120.746,121.613,121.154/)
>   latt  = (/25.049,24.12,23.07,22.013,24.05,22.765/)
>   lons  = (/121.513,120.684,120.197,120.746,121.613,121.154/)
>   lats  = (/25.037,24.145,22.995,22.003,23.975,22.752/)
>   text  = (/"Taipei","Taichung","Tainan","Hengchun","Hualian","Taitung"/)
>
>
> ;---Attach some dummy text strings
>   txres               = True
>   txres at txFontHeightF = 0.02
>   txres at txJust        = "BottomCenter"
>
>   text_id = gsn_add_text(wks,plot,text,lont,latt,txres)
> ;
>   mkres               = True
>   mkres at gsMarkerIndex = 16     ; Filled circle
>   mkres at gsMarkerSizeF = 0.01
>
>   locations = gsn_add_polymarker(wks,plot,lons,lats,mkres)
> ;====================================================
>   draw(plot)   ; This will draw the map and the shapefile outlines.
>   frame(wks)
> _______________________________________________
>
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