;***********************
; coneff_8.ncl
;
; Concepts illustrated:
;   - Drawing pressure/height contours
;   - Selectively coloring between contour levels (using an old method)
;
;***********************
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
;===========================
begin
;*************************
; get data
;*************************
 f     = addfile("atmos.nc","r") 
 u     = f->U(0,:,:,:)       
;*************************
; convert to pressure levels
;*************************
  hyam   = f->hyam
  hybm   = f->hybm
  ps     = f->PS 
  p0     = 1000.
  pres3d      = (/1000,950,800,700,600,500,400,300,200/)
  pres3d@units= "mb"

  uint=(/vinth2p(u,hyam,hybm,pres3d,ps(0,:,:),2,\
              p0,2,False)/)
  uint!0    = "plev"
  uint&plev = pres3d
  uint!1    = "lat"
  uint&lat  = u&lat
  uint!2    = "lon"
  uint&lon  = u&lon
  uint@long_name = "Zonal Wind"
 
  uzon=uint(:,:,0)
  uzon=dim_avg(uint)
 
;===========================
; plot parameters
;===========================
 wks   = gsn_open_wks ("ps", "coneff" )           ; open workstation
 res   = True                                     ; plot mods desired
 res@gsnDraw         = False                      ; do not draw  
 res@gsnFrame        = False                      ; do not advance frame
 res@cnLevelSpacingF = 4.0                        ; contour level spacing
 res@cnInfoLabelOn   = False                      ; turn off contour label
 
 plot = gsn_csm_pres_hgt(wks, uzon, res ) 
 plot = ColorShadeLeGeContour(plot,10.,"salmon",20.,"cyan")

 draw(plot)
 frame(wks)

end