Ploting Hurricane track from GFS ensembles

[Jennifer Adams]

On Aug 19, 2009, at 2:27 PM, PiotrD wrote:
>
> Does anybody have script that can make hurricane track from GFS
> ensembles?
>

I wrote the script below to use TIGGE forecasts to draw forecasted
hurricane tracks when Ike was entering the Gulf of Mexico in September
2008. An example of the final product is here:

http://iges.org/grads/Ike_2008090912_12z09sep2008_ecmf.png
http://iges.org/grads/Ike_2008090912_12z09sep2008_kwbc.png

You'll have to modify the script a bit to allow for your data layout.
Basically, the script take the minimum of SLP over a small area, using
minloc to find the grid location, converting it to x,y coordinates,
drawing a dot for each forecast interval, then connecting all the dots
for each ensemble member. If you compare the two images, you'll see
what a difference grid resolution can make. The ECMWF (ecmf) grid is
~0.45 degrees, NCEP (kwbc) is 1.0.


function main(arg)
'reinit'
*initdate='2008090912'
initdate=subwrd(arg,1)
firsttime = '12z09sep2008'
lasttime  = '00z13sep2008'
path='/put_your_path_here/ctl/'initdate
models='ammc babj cwao ecmf egrr kwbc rksl sbsj'
colors='2    6    8    14   4    11   3    13'
nmodels=8
models='kwbc babj cwao ecmf sbsj'
colors='11   2    8    3    14  '
nmodels=4


minlat=20
maxlat=31
minlon=261
maxlon=281

'set rgb 98 66 110 44'
'set rgb 99 60 60 60'

verb=0
threshold=1008
marksize=0.04

'set warn off'
cnt=0
m=1
while(m<=nmodels)
  model=subwrd(models,m)
  color=subwrd(colors,m)
  'open 'path'/'model'/sl.ctl'
  'set dfile 'm
  'set t 2'
  'set lon 'minlon' 'maxlon
  'set lat 'minlat' 'maxlat
  'q file 'm
  sizes = sublin(result,5)
  esize = subwrd(sizes,15)
  if (cnt=0)
   'clear'
   'set clab off'
   'set gxout contour'
   'set ccolor 0'
   'set grads off'
   'set grid on'
   'set map 1'
   'set xlint 3'
   'set ylint 2'
   'set mpdset hires'
   'd msl(e=1)'
   'basemap L 99 98 hires'
   'printim bg0.png x1100 y850'
   'q gxinfo'
   xlims=sublin(result,3)
   ylims=sublin(result,4)
   gxmin=subwrd(xlims,4)
  endif
  if (1)
   'clear'
   'set clab off'
   'set gxout contour'
   'set ccolor 0'
   'set grads off'
   'set grid off'
   'set annot 0'
   'set map 0'
   'd msl(e=1)'
  endif
  e=1
  while (e<=esize)
   'set dfile 'm
   'set e 'e
   'set time 'firsttime' 'lasttime
   'q dims'
   times=sublin(result,5)
   t1=subwrd(times,11)
   t2=subwrd(times,13)
   t=t1
   slp='maskout(msl/100,'threshold'-msl/100)'
   cmd='draw line'
   while (t<=t2)
     'set t 't
*   get the grid locations of the slp minimum
     'd
minloc(min('slp',lon='minlon',lon='maxlon'),lat='minlat',lat='maxlat')'
     line1=sublin(result,1)
     line2=sublin(result,2)
     word1=subwrd(line1,1)
     if (word1="Notice:")
       yloc=subwrd(line2,4)
     else
       yloc=subwrd(line1,4)
     endif
     'd
minloc(min('slp',lat='minlat',lat='maxlat'),lon='minlon',lon='maxlon')'
     line1=sublin(result,1)
     line2=sublin(result,2)
     word1=subwrd(line1,1)
     if (word1="Notice:")
       xloc=subwrd(line2,4)
     else
       xloc=subwrd(line1,4)
     endif
     if (xloc < 9.999e+20 & yloc < 9.999e+20 & xloc > -9.999e+30 &
yloc > -9.999e+30)
*     convert these to world coordinates
       'q gr2xy 'xloc' 'yloc
       line1=sublin(result,1)
       line2=sublin(result,2)
       word1=subwrd(line1,1)
       if (word1="Notice:")
        xpos = subwrd(line2,3)
        ypos = subwrd(line2,6)
       else
         xpos = subwrd(line1,3)
         ypos = subwrd(line1,6)
       endif
       if (xpos != gxmin)
         'set line 'color
         'draw mark 3 'xpos' 'ypos' 'marksize
         cmd = cmd' 'xpos' 'ypos
         if (verb); say 'm='m' xloc='xloc' yloc='yloc'  xpos='xpos'
ypos='ypos; endif
       endif
       cnt=cnt+1
     endif
     t=t+2
   endwhile
   cmd ;* draw the line
   e=e+1
  endwhile
  'printim Ike_'initdate'_'firsttime'_'model'.png -t 0 -b bg0.png
x1100 y850'
  m=m+1
endwhile
say 'cnt='cnt


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