How can I use fortran to read a Grads binary data file
Xiaofeng Gong
xgong at IRI.COLUMBIA.EDU
Thu Sep 15 11:34:27 EDT 2005
In addition to byteswapped problem, I think the fortran segment is also
wrong in reading the binary file. the i,j loops are put in a wrong place.
it should be something like: read(17,REC=irec) berg
On Thu, 15 Sep 2005, Ming Yang wrote:
> Hi,
> Thank you for your help. I still cannot figure out how to read it. Here
> is the descriptor file
>
> DSET ^topo-ice5g.t21.bin
> UNDEF -9.99e+33
> options byteswapped
> XDEF 64 LINEAR 0 5.6250
> YDEF 32 LEVELS
> -85.761 -80.269 -74.745 -69.213
> -63.679 -58.143 -52.607 -47.070
> -41.532 -35.995 -30.458 -24.920
> -19.382 -13.844 -8.307 -2.769
> 2.769 8.307 13.844 19.382
> 24.920 30.458 35.995 41.532
> 47.070 52.607 58.143 63.679
> 69.213 74.745 80.269 85.761
> ZDEF 1 LINEAR 1 1
> TDEF 1 LINEAR JAN1960 1MO
> VARS 1
> TOPO 1 99 Ice
> ENDVARS
>
> And here is my fortran program
>
> program readbin
> integer nlat,nlon,irec
> parameter (nlon=64, nlat=32)
> real*4 berg(nlat,nlon)
>
> OPEN(17,file='topo-ice5g.t21.bin',
> &STATUS='UNKNOWN',
> &FORM='UNFORMATTED',ACCESS='DIRECT', RECL=64*32)
>
>
> irec=1
> do i=1,nlat
> do j=1,nlon
>
> read(17,REC=irec) berg(i,j)
> irec=irec+1
> write(*,*) berg(i,j)
>
> enddo
> enddo
>
> end
>
>
> Here is what I got after run this fortran program
>
> -2.8802414E-11
> 3.4926203E-10
> 3.3586933E-22
> -1.3897608E-11
>
> ****** FORTRAN RUN-TIME SYSTEM ******
> Error 1066: record not in file
> Location: the READ statement at line 15 of "readbin.f"
> Unit: 17
> File: topo-ice5g.t21.bin
> Abort
>
> The print out number is definetely wrong according the display of the
> data in Grads. But I don't know how to fix it.
>
>
> Best,
> Ming
>
>
> On Thu, 15 Sep 2005, [ISO-8859-1] Heiner Körnich wrote:
>
> > Hi Ming,
> >
> > GrADS is using standard binary data. Depending on your option in .ctl,
> > you read it with direct access for no option and sequential acces for
> > "sequential" option. do you mean sequential with stream?
> > Details to fortran are here:
> > http://www.geocities.com/Athens/Olympus/5564/prof77.htm
> >
> > Cheers,
> > Heiner
> >
> > Ming Yang wrote:
> >
> > > Hi, guys
> > > I have a Grads binary file and I want to use a fortran program to
> > > read it
> > > and write to an ASCII file. Do you know how can I do that. I know the
> > > binary
> > > file is a "stream" file and I am supposed to use direct access to read
> > > it,
> > > right? Thank you for your attention.
> > >
> > > Best,
> > > Ming
> > >
> > > Ming Yang
> > > Department of Geological Sciences
> > > University of North Carolina at Chapel Hill
> > > myang at email.unc.edu
> > > 919-843-5846
> > >
> > >
> >
> > --
> > Heiner Körnich
> > Dept. of Meteorology Tel: +46 8 164333
> > Stockholms University
> > S-106 91 Stockholm, Sweden Email: heiner at misu.su.se
> >
>
--
_______________________________________________________
Xiaofeng Gong
International Research Institute for climate prediction
The Earth Institute at Columbia University
229 Monell, 61 Route 9W, Palisades, NY 10964
-------------------------------------------------------
Phone: (845)680-4431 Fax:(845)680-4865
Email: xgong at iri.columbia.edu
WWW: http://iri.columbia.edu/~xgong
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