[gradsusr] Multiple netcdf files in one control file

mehwish ramzan mehwish.ramzan at gmail.com
Tue May 13 01:28:38 EDT 2014


Dear Jim and Charles,

Thank you so much for your kind reply and help.
Based upon Jim's suggestions, I prepared the following control file by
using %ch template to use multiple files like below;

dset ^cru_ts3.21.%ch.tmp.dat.nc
chsub   1  120 1971.1980
chsub 121  240 1981.1990
chsub 241  360 1991.2000
options template
title cru_ts3.21 near-surface temperature
undef -9.99+08
xdef  720 linear 0.0     0.5
ydef  360 linear -89.75  0.5
zdef    1 levels 0  0
tdef  480 linear jan1971 1mo
vars    1
 tmp 0 -999  near-surface temperature
endvars


Also based upon Charles kind suggestion I checked for dtype netcdf but as I
just followed the this link *http://www.iges.org/grads/gadoc/templates.html
<http://www.iges.org/grads/gadoc/templates.html> *when first prepared the
control file so I am not sure whether dtype option is needed or not? (sorry
for my poor understanding)

But when I exclude the dtype option from control file, it opened in GrADS
but the output image was incorrect.

The correct output from original netcdf file as well as the one prepared
using above ch. ctl  is attached.
Kindly guide me further in this regards or suggest me an alternate method
(such as using fwrite script etc.)

I will be grateful

Thank you

With Best Regards,

Mehwish





On Tue, May 13, 2014 at 7:22 AM, Charles Seman - NOAA Federal <
charles.seman at noaa.gov> wrote:

> Mehwish,
>
> from http://grads.iges.org/grads/gadoc/descriptorfile.html#VARS
> ---
> units
> (DTYPE netcdf,
> hdfsds, or hdf5_grid)
>
> (GrADS version 1.9) For DTYPE netcdf or hdfsds or hdf5_grid (GrADS
> version 2.0.a7+) , the units field is a comma-delimited list of the
> varying dimensions of the variable. Dimensions expressed as x, y, z, or
> t correspond to the four axes defined by XDEF, YDEF, ZDEF and TDEF. For
> example, a surface variable such as sea level pressure might look like
> this:
>
>      presSFC=>psfc   0   y,x   Surface Pressure
> ---
>
> would the above apply since you are using "dtype netcdf"?
>
> Hope this helps,
> Chuck
>
> On 05/12/2014 03:11 PM, James T. Potemra wrote:
> > Mehwish,
> >
> > I think the problem is your file names contain different decades, so in
> > your .ctl file where you have:
> >
> > DSET  cru_ts3.21.%x31.%x30.tmp.dat.nc
> >
> > the %x3 will be the same.  For example, the first time through the
> > substitution will be 197, or
> >
> > DSET cru_ts3.21.1971.1970.tmp.dat.nc
> >
> > One way around this would be to instead use chsub:
> >
> > DSET ^cru_ts3.21.%ch.tmp.dat.nc
> > CHSUB     1 120 1971.1980
> > CHSUB 121  240 1981.1990
> > CHSUB 241  360 1991.2000
> > OPTIONS template
> > DTYPE netcdf
> >
> > More details at http://www.iges.org/grads/gadoc/templates.html
> >
> > Jim
> >
> > On 5/11/14 9:02 PM, Malleswararao Maguluri wrote:
> >> Hi,
> >>
> >>    Better to use cdo for calculating climatology. otherwise you can
> >> combine your decadal files as a single file using cat command in cdo
> >> and use it as input to grads.
> >>
> >> Thanks & regards,
> >>
> >>
> >> On Mon, May 12, 2014 at 12:18 PM, mehwish ramzan
> >> <mehwish.ramzan at gmail.com <mailto:mehwish.ramzan at gmail.com>> wrote:
> >>
> >>     Dear GrADS community,
> >>
> >>     I am trying to merge multiple netcdf files into one control file
> >>     so that i can calculate the climatology of 25 years. The data is
> >>     available in decadal format like this;
> >>
> >>     cru_ts3.21.1971.1980.tmp.dat.nc
> >>     <http://cru_ts3.21.1971.1980.tmp.dat.nc>
> >>     cru_ts3.21.1981.1990.tmp.dat.nc
> >>     <http://cru_ts3.21.1981.1990.tmp.dat.nc>
> >>     cru_ts3.21.1991.2000.tmp.dat.nc
> >>     <http://cru_ts3.21.1991.2000.tmp.dat.nc>
> >>     cru_ts3.21.1991.2000.tmp.dat.nc
> >>     <http://cru_ts3.21.1991.2000.tmp.dat.nc>
> >>
> >>     while the information of one .nc file is as;
> >>
> >>     File 1 : CRU TS3.21 Mean Temperature
> >>
> >>     Descriptor: cru_ts3.21.1971.1980.tmp.dat.nc
> >>     <http://cru_ts3.21.1971.1980.tmp.dat.nc>
> >>
> >>     Binary: cru_ts3.21.1971.1980.tmp.dat.nc
> >>     <http://cru_ts3.21.1971.1980.tmp.dat.nc>
> >>
> >>     Type = Gridded
> >>
> >>     Xsize = 720Ysize = 360Zsize = 1Tsize = 120
> >>
> >>     Number of Variables = 1
> >>
> >>     tmp 0 -999 near-surface temperature
> >>
> >>     By following some previous posts regarding same issue, according
> >>     to my understanding i prepared one ctl file which can be used as a
> >>     combination of above four separate files. The .ctl file is as
> follows;
> >>
> >>     DSETcru_ts3.21.%x31.%x30.tmp.dat.nc <http://x30.tmp.dat.nc>
> >>
> >>     OPTIONS template
> >>
> >>     DTYPE netcdf
> >>
> >>     XDEF 720 linear -89.75 89.75
> >>
> >>     YDEF 360 linear 0 360
> >>
> >>     ZDEF1 linear 1000
> >>
> >>     TDEF 480 linear jan1971 1mo
> >>
> >>     vars 1
> >>
> >>     tmp 099 near-surface temperature
> >>
> >>     endvars
> >>
> >>
> >>     But when i tried to open this control file. It give error message;
> >>
> >>     Invalid variable record
> >>
> >>     --> The invalid description file record is:
> >>
> >>     --> tmp 0 -999 near-surface temperature
> >>
> >>     The data file was not opened.
> >>
> >>     I know i am making mistake in preparing ctl file but i don't know
> >>     how to put right information ?
> >>
> >>     Please help me in solving this issue.
> >>
> >>
> >>     Thank You
> >>
> >>
> >>     With Best Regards,
> >>
> >>
> >>     Mehwish
> >>
> >>
> >>
> >>
> >>
> >>
> >>     _______________________________________________
> >>     gradsusr mailing list
> >>     gradsusr at gradsusr.org <mailto:gradsusr at gradsusr.org>
> >>     http://gradsusr.org/mailman/listinfo/gradsusr
> >>
> >>
> >>
> >>
> >> --
> >> M. MALLESWARA RAO
> >> M.Tech (Atmospheric Science) & M.Sc (Physics)
> >>
> >>
> >>
> >> _______________________________________________
> >> gradsusr mailing list
> >> gradsusr at gradsusr.org
> >> http://gradsusr.org/mailman/listinfo/gradsusr
> >
> >
> >
> > _______________________________________________
> > gradsusr mailing list
> > gradsusr at gradsusr.org
> > http://gradsusr.org/mailman/listinfo/gradsusr
> >
>
> --
>
> Please note that Charles.Seman at noaa.gov should be considered my NOAA
> email address, not cjs at gfdl.noaa.gov.
>
> ********************************************************************
>   Charles Seman                                Charles.Seman at noaa.gov
>   U.S. Department of Commerce / NOAA / OAR
>   Geophysical Fluid Dynamics Laboratory         voice: (609) 452-6547
>   201 Forrestal Road                              fax: (609) 987-5063
>   Princeton, NJ  08540-6649            http://www.gfdl.noaa.gov/~cjs/
> ********************************************************************
>
> "The contents of this message are mine personally and do not reflect any
> official or unofficial position of the United States Federal Government,
> the United States Department of Commerce, or NOAA."
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