load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin
  fu = addfile("$NCARG_ROOT/lib/ncarg/data/cdf/Ustorm.cdf","r")
  fv = addfile("$NCARG_ROOT/lib/ncarg/data/cdf/Vstorm.cdf","r")

  itime = 0

  u = fu->u(itime,:,:)       ; Select first timestep.
  v = fv->v(itime,:,:)

  wks = gsn_open_wks("x11","vector_ex05")

  res                       = True          ; Plot options desired.

  res@gsnMaximize           = True          ; Maximize plot in frame.

  cmap                      = read_colormap_fuil("rainbow")
  res@vcLevelColors         = cmap(16:,:)

  res@vcMonoLineArrowColor  = False        ; Turn on color vectors.
  res@vcRefMagnitudeF       = 20           ; Define reference magnitude.
  res@vcRefLengthF          = 0.045        ; Define length of vector reference.
  res@vcLineArrowThicknessF = 2.           ; Double the thickness.

  res@vcRefAnnoOrthogonalPosF = -0.179     ; Move reference annotation up
  res@vcRefAnnoParallelPosF   =  0.19      ; and over to left.

  res@vcLevelSelectionMode    = "ExplicitLevels"   ; Explicitly set
  res@vcLevels                = ispan(2,28,2)      ; vector levels.

  res@lbOrientation           = "Vertical"  ; Move labelbar to side.

  res@tiMainString = fu->reftime + " + " + fu->timestep(itime)

  plot = gsn_csm_vector(wks,u,v,res)
end