How can I use fortran to read a Grads binary data file

[Heiner Körnich]

Hi,
so far, ok. But your data is byteswapped, which means the byte order is
reversed, which means, if you are on a PC, your data comes from a UNIX
workstation, or vice versa. It is the "little-endian, big-endian" problem.
Search this keyword on the Grads-list or use the program from here:
http://www.gfdl.noaa.gov/products/vis/utilities/GFDL_VG_Utilities.html#byteswap

Good luck,
Heiner

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 K�rnich 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 K�rnich
>>Dept. of Meteorology                    Tel:    +46 8 164333
>>Stockholms University
>>S-106 91 Stockholm, Sweden              Email:  heiner at misu.su.se
>>
>>
>>
>
>
>
>

--
Heiner Körnich
Dept. of Meteorology                    Tel:    +46 8 164333
Stockholms University
S-106 91 Stockholm, Sweden              Email:  heiner at misu.su.se