DKRZ NCL FESOM grid example

DKRZ NCL script:

;---------------------------------------------------------------
; DKRZ - NCL Example:   NCL_FESOM_grid.ncl
;
; Grid type:    unstructured grid
;
; Settings:     polygons filled with color yellow
;
; Data files:   FESOM_testmesh.convex.nc (nv=9)
;               FESOM_testmesh.exact.nc  (nv=18)
;
; NCL version:  requires 6.2.x for faster polygon drawing
;               uses resource gsSegments
;
; 2015-03-17  kmf
;---------------------------------------------------------------
begin
  start_date = toint(systemfunc("date +%s"))          ;-- computing start time

;-- define file name
  diri = "$HOME/data/FESOM/"                          ;-- can't be provided - sorry!

;-- choose data file
  fili  = "FESOM_testmesh.convex.nc"

;-- open file
  f =  addfile(diri + fili, "r" )

;-- define the cell polygon points
  vlon    =  f->lon_vertices                           ;-- cell longitude vertices
  vlon    =  where(vlon.lt.0, vlon + 360, vlon)        ;-- longitude: 0-360
  vlat    =  f->lat_vertices                           ;-- cell latitude vertices
  nv      =  dimsizes(vlon(0,:))                       ;-- number of points in polygon

;-- print some information to stdout
  print("")
  print("Data longitude Min:   " + min(vlon))
  print("               Max:   " + max(vlon))
  print("    Polygon points:   " + nv)
  print("")

;-- open workstation
  wks = gsn_open_wks("png","plot_FESOM_grid_convex")     ;-- open a workstation

;-- set resources
  mres                        =  True
  mres@gsnDraw                =  False
  mres@gsnFrame               =  False
  mres@gsnMaximize            =  True

  mres@tiMainString           =  "FESOM grid"

  mres@mpFillOn               =  True                    ;-- fill map grey
  mres@mpOutlineOn            =  True                    ;-- outline map
  mres@mpGridLineColor        = "grey60"                 ;-- grid line color
  mres@mpGridAndLimbOn        =  False                   ;-- draw grid lines
  mres@mpGeophysicalLineColor = "black"                  ;-- outline color
  mres@mpGeophysicalLineThicknessF = 1.5                 ;-- thickness of continental outlines
  mres@mpPerimOn              =  False                   ;-- don't draw the box around the plot
  mres@mpDataBaseVersion      = "MediumRes"              ;-- map resolution
  mres@mpGreatCircleLinesOn   =  False                   ;-- important: v6.2.0 False !!
  mres@mpOceanFillColor       = (/ 0.824, 0.961, 1.0 /)  ;-- light blue
  mres@mpInlandWaterFillColor = (/ 0.824, 0.961, 1.0 /)  ;-- light blue
  mres@mpLandFillColor        = (/ 0.7, 0.7, 0.7 /)      ;-- beige
  mres@mpPerimOn              =  False                   ;-- don't draw the box around the plot
  mres@mpMinLonF              =  88
  mres@mpMaxLonF              = 162
  mres@mpMinLatF              = -22
  mres@mpMaxLatF              =  22

;-- draw the map
  map = gsn_csm_map(wks,mres)                            ;-- create the map

;-- set polygon resources
  pres                      =  True
  pres@gsEdgesOn            =  True                      ;-- draw polygon edges
  pres@gsEdgeColor          = "grey20"                   ;-- polygon outline color
  pres@gsFillColor          = "yellow"                   ;-- polygon fill color
  pres@gsFillOpacityF       =  0.5                       ;-- polygon opacity
  pres@gsSegments           =  ispan(0,dimsizes(vlon(:,0))*nv, nv)

  gsid = gsn_add_polygon(wks,map,ndtooned(vlon),ndtooned(vlat),pres)

  draw(map)
  frame(wks)

  end_date = toint(systemfunc("date +%s"))               ;-- computing time
  print("-->  Used CPU time:  "+(end_date-start_date)+"s")

end

Result: