; ===========================================
; coneff_1.ncl
;
; Concepts illustrated:
;   - Drawing Hovmueller plots
;   - Drawing the zero contour line thicker
;
; ===========================================
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin
;=============================================
; data processing
;=============================================
 fili  = "chi200_ud_smooth.nc"                 ; filename
 
 f     = addfile (fili , "r")                  ; add file

 chi   = f->CHI                                ; get chi
 chi   = chi/1.e6                              ; scale for convenience
; ===========================
; create plot
; ===========================
 wks   = gsn_open_wks ("ps", "coneff")       ; open ps file
 gsn_define_colormap(wks,"gui_default")        ; choose color map

 res                 = True                    ; plot mods desired
 res@gsnDraw         = False                   ; don't draw yet
 res@gsnFrame        = False                   ; don't advance frame yet

 res@tiMainString    = "Pacific Region"        ; title
 res@cnLevelSpacingF = 2.                      ; contour interval

 res@cnFillOn        = True                    ; turn on color

;---This resource not needed in NCL V6.1.0
 res@gsnSpreadColors = True                    ; use full colormap

 res@gsnContourZeroLineThicknessF = 2.	       ; doubles thickness of zero contour
 plot = gsn_csm_hov(wks, chi(:,{100:220}), res) 

 draw(plot)
 frame(wks)
end