;----------------------------------------------------------------------
; vector_4.ncl
;
; Concepts illustrated:
;   - Coloring vectors based on temperature data
;   - Drawing curly vectors
;   - Thinning vectors using a minimum distance resource
;   - Changing the length of the smallest vector as a fraction of the reference vector
;----------------------------------------------------------------------

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

begin

;---Read in netCDF file
  a = addfile("uwnd.mon.mean.nc","r")
  b = addfile("vwnd.mon.mean.nc","r")
  
 ;---Read in zonal [u] and meridional [v] winds 
  u = a->uwnd 
  v = b->vwnd
  ;u1 = u(1,:,:)    ;dimension reduction
  ;v1 = v(1,:,:)  
  time =a->time
  time :=b->time
  ntim =dimsizes(time)
  U =a->uwnd(0:803,:,:)
  V =b->vwnd(0:803,:,:)
  printVarSummary(U)
  printVarSummary(V)
    
  mnU=clmMonTLL(U)

  mnV=clmMonTLL(V)

  wspdAv=sqrt(mnU^2+mnV^2)

  ;  printMinMax(wspdAV,0)
  printMinMax(mnU,0)
  printMinMax(mnV,0)
  printVarSummary(mnU)
  printVarSummary(mnV)
  printVarSummary(time)
  
  
  months = (/"Jan", "Feb", "Mar", "April" \
            ,"May", "June", "July", "August"\
            ,"Sept", "Oct", "Nov"      \
            ,"Dec" /)


;---Create plot
  wks = gsn_open_wks("x11","vector")                       ; open a ps file

  cmap = read_colormap_file("BlAqGrYeOrReVi200")

  vcres                     = True      ; plot mods desired
  vcres@lbLabelStride       = 2         ; plot every other colar bar label
  vcres@vcRefMagnitudeF         = 5.0              ; make vectors larger
  vcres@vcRefLengthF            = 0.050            ; ref vec length
  vcres@vcGlyphStyle            = "CurlyVector"    ; turn on curly vectors
  vcres@vcMinDistanceF          = 0.017            ; thin out vectors
  vcres@vcLevelPalette      = cmap(6:193,:)

  vcres@tiMainString            = "Zonal and Meriodanal Flows 1948-2015"
  ;****************ZOOM INTO YOUR LOCATION*********************
  
  vcres@mpLimitMode           = "LatLon"
 ;res@mpOutlineOn		  =True
 ;res@mpOutlineSpecifiers     =True
  vcres@mpMinLonF            = 21.               ; select a subregion
  vcres@mpMaxLonF            = 54.
  vcres@mpMinLatF            = -12. 
  vcres@mpMaxLatF            = 22.5
  
  
  ;res@mpLandFillColor      = "background"       ; color of land
  
  ;*********************Masking*********************************
 

  vcres@mpFillDrawOrder = "Postdraw"  
    
  vcresMap= True 
  vcresMap@mpPerimOn = False 
  vcresMap@mpGridAndLimbOn = False 
  vcresMap@gsnTickMarksOn = False 
  vcresMap@mpDataSetName = "Earth..3" 
  vcresMap@mpOutlineOn = True 
  
  vcres@mpFillOn               = False        ; turn off gray fill
  vcres@mpOutlineBoundarySets  = "National"   ; turn on country boundaries
   
  vcresMap@mpFillOn = True 

  vcresMap@mpOceanFillColor = "transparent" 
  vcresMap@mpLandFillColor = "transparent" 
  vcresMap@mpInlandWaterFillColor = "transparent" 
   
   vcres@mpDataBaseVersion = "MediumRes"            ; choose higher resolution
   delete(U@units)
  delete(U@long_name)
  delete(V@units)
  delete(V@long_name)
  vcres@gsnCenterString = "" 
  vcres@gsnLeftString = "" 
  
  ;************************************************
; create panel plots
;*************************************************
  plot   = new (12 , graphic)                    ; create graphical array

   
  vcresP                      = True               ; plot options desired
     
 i = 0                                        ; wind Climatologies
 do nmo=0,11,1                                 ; loop over the months
 

  vcres@gsnCenterString   = months(nmo)+":"+time(0)/100 +"-"+ time(ntim-1)/100
  
   plot(i)= gsn_csm_vector_scalar_map_ce(wks,mnU(i),mnV(i),wspdAV(i),vcres)  ; create plot
  
   
  i = i+1
   gsn_panel(wks,plot,(/3,4/),vcresP)

 end do
  end