[gradsusr] GFS With Climatology

[Jennifer M Adams]

Hi, Stuart —
There is an example for creating a monthly climatology in the documentation for the ‘modify’ command — http://cola.gmu.edu/grads/gadoc/gradcomdmodify.html. Write out the defined climo to disk (using fwrite instead of sdfwrite so there is no time metadata attached to the file) and create a new data set (an example descriptor is copied below). The script sample is taken from what I use to create the temperature anomaly plots in the climate outlooks at  http://wxmaps.org/pix2/clim.html. Most of this code is for figuring out weights (fac1 and fac2) for the monthly climatology values in order to match the time period of the 8-day average from the GFS forecast; that may be more complicated than necessary, you could probably just as easily use the climatology for the current month.
—Jennifer



'open /data/gfs0p25/ctl/latest.gfs'
'open /data/tclim.ctl'
setcols()
chrmon     = 'JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC'
julian     = '  0  31  59  90 120 151 181 212 243 273 304 334'
julian_mid = ' 15  45  74 105 135 166 196 227 258 288 319 349 380'

tlast=65
'set dfile 1'
'set t 'tlast
'q time'
txtdat = subwrd(result,3)
txtday = substr(txtdat,4,2)
txtmon = substr(txtdat,6,3)
imon = 1
while(imon<13)
  lmon = imon - 1
  monmon = subwrd(chrmon,imon)
  if (monmon = txtmon)
    if (imon > 1)
      res = subwrd(julian,imon)
    else
      res = 0
    endif
    mrfjul = res + txtday
    break
  endif
  imon = imon + 1
endwhile
midjul = subwrd(julian_mid,imon)
if(mrfjul < midjul)
  mon1 = imon - 1
  mon2 = imon
  if (mon1 = 0)
    jul1 = -15
    mon1 = 12
  else
    res = subwrd(julian_mid,mon1)
    jul1 = res
  endif
  jul2 = midjul
  fac1 = (jul2-mrfjul)/(jul2-jul1)
  fac2 = (mrfjul-jul1)/(jul2-jul1)
else
  mon1 = imon
  mon2 = imon + 1
  res = subwrd(julian_mid,mon2)
  jul2 = res
  jul1 = midjul
  fac1 = (jul2-mrfjul)/(jul2-jul1)
  fac2 = (mrfjul-jul1)/(jul2-jul1)
  if (mon2 = 13)
    mon2 = 1
  endif
endif
time1 = mon1
time2 = mon2

* Define mean temperature
'set dfile 1'
'set t 1'
'tfcst = ave(t2m.1-273.16,t=2,t='tlast')'

* Define the climatological temperature for this period
'set dfile 2'
'set t 1'
'tclim = t(t='time1')*'fac1'+t(t='time2')*'fac2

* Draw the anomaly
'd tfcst-lterp(tclim,tfcst)'

p.s. The contents of the descriptor file (tclim.ctl) look like this:

DSET ^tclim.dat
UNDEF -9.99e+33
TITLE CRU mean surface temperature climatology 1901-2000 Regridded
XDEF 360 linear 0 1
YDEF 181 linear -90 1
ZDEF   1 LEVELS 1
TDEF  12 LINEAR JAN1979 1mo
VARS 1
t 0 0 mean temperature [C]
ENDVARS

On Apr 14, 2016, at 5:50 AM, Chorley Weather <weatherstu at chorleyweather.com<mailto:weatherstu at chorleyweather.com>> wrote:


Hi all,

I've wanted to create anomaly charts for some time now using data from the GFS along side climatology data, say from 1981-2010, perhaps using CFSR. However I'm unsure where to start with this really, is there anybody who could throw some advice or perhaps an old script that I could teach myself. Any help would be greatly appreciated.

Best regards,

--

Stuart Markham

[http://www.chorleyweather.com/forecast-charts/SampleDatasets/logo%20450x100.PNG]

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--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University



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