;This ncl script will plot the DEC SO2 data
;
begin
;************************************
       f = "50-21-0002-SO2-1990-2012.Final.out"

       data = asciiread(f,(/11323,17/),"double")

        x =  data(:,0)
        x@long_name = "Date/Time"

        y = data(:,14)
        y@long_name = "SO2 concentration (ppb)"
       y@_FillValue=integertoshort(-999)
        y=where(y.lt.0,y@FillValue,y)
;************************************
; Plotting parameters
;************************************
        plot = new (1, "graphic")
        wks = gsn_open_wks ("png","50-021-0002-SO2-1990-2019")
        ntStrt = 1990
        ntLast = 2020
        res = True
        res@tiMainString = "" ; Title
        res@trXMinF         = 1990  ; set minimum X-axis value
        res@trXMaxF         = 2020      ; set maximum X-axis value
        txres                   =  True
        txres@txFontHeightF     =  0.02
        txres@txJust            = "CenterLeft"
        txres@txFontThicknessF  =  2.0      ; default=1.00
        txres@txFontHeightF     =  0.025    ; default=0.05



        p = trend_manken(y(ntStrt:ntLast), False, 0)

        res@tmXBMode        = "Explicit"
        plot = gsn_csm_xy (wks,x,y,res) ; create plot
        text = "trend="+sprintf("%5.3f",p(1))
        txt_winter = gsn_add_text(wks,plot(0),text, 1990, 40,txres)
end