Parameterized Chemistry and Transport Model

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Archived Datasets

Exp. # Dates/Length Dynamics Constituents Archive Location
321 Begin: 0:00 UTC Wed 1 Jan 1997
End: 0:00 UTC Thu 1 Jan 1998 		GEOS1 CHBr3
Bry 		dirac:/u3/y3jen/ctm/chbr3/exp321
403 Begin: 0:00 UTC Wed 1 Jan 1997
End: 0:00 UTC Thu 1 Jan 1998 		GEOS1 CO2 dirac:/u3/y3jen/ctm/co2/exp403
405 Begin: 0:00 UTC Mon 7 Dec 1998
End: 0:00 UTC Tue 21 Dec 1999 		TRMM02 CO2 dirac:/u3/y3jen/ctm/co2/exp405
411 Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/srk03/zhu/exp411
411.new Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/ard01/zhu/exp411.new
413 Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 6 Jan 1999 		fvDAS SF6 /misc/ard01/zhu/exp413
413.new Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 6 Jan 1999 		fvDAS SF6 /misc/ard01/zhu/exp413.new
414 Begin: 0:00 UTC 1 Jan 0066
End: 0:00 UTC 6 Jan 0067 		fvGCM SF6 /misc/ard01/zhu/exp414
416 Begin: 0:00 UTC 1 Jan 1992
End: 0:00 UTC 13 Jul 1997 		UKMO SF6 /misc/ard01/zhu/exp416
411.veg Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/ard01/zhu/exp411.new/veg
411.ocn Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/ard01/zhu/exp411.new/ocn
411.fos Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/ard01/zhu/exp411.new/fos
417 Begin: 0:00 UTC 1 Jan 1998
End: 0:00 UTC 26 Dec 1999 		fvDAS CO2 /misc/ard01/zhu/biomass.burn/history_file

Dataset retrieval

The following set of commands retrieves one PCTM history dataset from Unitree and places the copy in the present working directory. An account on Unitree is a prerequisite.

ftp dirac 1021
cd /u3/y3jen/ctm/chbr3/exp321
get p321.chbr3.b19970526z00.e19970531z00
bye

Instructions for reading archived datasets with IDL

The following IDL procedure will read the PCTM history files. Before proceeding, place

/home/nielsen/tools/idl

in your IDL path. This routine calls

/home/nielsen/tools/idl/pctmr3d.pro.

Only a limited number of keywords are shown below, and the user is encouraged to review the in-line documentation for pctmr3d to become familiar with the complete list. There are three required parameters: the filename is supplied by the user, but lun, the logical unit number, and lenhdr, the length of the header record, are assigned by pctmr3d.

In general, several writes spanning several days comprise each history file. To find how many "steps" are on a file, use the beginning and ending dates from the history file name along with the keyword dthistory which tells how often the history file is appended. For each time stamp, there is (1) a header record which contains grid parameters, date and time stamps, and other useful information, (2) the surface pressure, and (3) the global data array.

The keyword configure controls opening the file, closing the file, and assigning a logical unit number. The accepted values are:

In the example below, the history file spans five simulated days and the write interval is six hours. There are thus 21 "steps." On the first pass through the for-loop, the file is opened, the logical unit number is assigned, and the first header, surface pressure, and CHBr3 records are read before returning. The next nineteen calls to pctmr3d require no action from configure. For the twenty-first read, configure is set to -1 so that the file will be closed and the logical unit number freed after the data is read.

filename='/misc/abc01/mydir/p321.chbr3.b19970526z00.e19970531z00'
nsteps=21

for n=0,nsteps-1 do begin

case n of
0: configure=1
nsteps-1: configure=-1
else: configure=0
endcase

pctmr3d,filename,lun,lenhdr,configure=configure,data=data,dthistory=dthistory,$
latitudes=latitudes,latsize=latsize,layers=layers,longitudes=longitudes,$
lonsize=lonsize,nowday=nowday,sfcprs=sfcprs

endfor
stop
end

A more complete example which prints out a selection of the keywords is found in
/home/nielsen/tools/idl/pctm_sample_read.pro

You can also use GrADS to view and treat the model output. We have developed a postprocessing procedure to read the history files using FORTRAN programs. The postprocessing can also do vertical interpolation to some standard pressure levelssi, and do daily mean, etc.. The postprocessed data can be then easily viewed and treated with GrADS, which is vey convenient.

If you are interested to use GrADS for the CTM output, please contact zhu@code916.gsfc.nasa.gov