[gradsusr] Fortran to Read in GrADS Binary File

Tue Jul 5 12:44:57 EDT 2016

Hi Lydia,

You have a couple problems.  First, you are reading in tmax, tmin, prcp 
then srad, but then you write out tmin, tmin prcp and srad (tmin 
twice).  Second, your program is reading and writing to the same 
variables, and then only the first 8x8 (lower left "corner" of the data 
sets).  Perhaps these are all missing ?

Finally, the record length is defined to be 464 by 224, then you only 
define (via read) and write the first 8 by 8, which should work ok, but 
recognize that the rest of the 464x224 array has not been defined.  So, 
if you want to use your control file with "xdef 8" and "ydef 8" you'll 
need to change your "open" statement for the output file to be 8*8*4 and 
not 464*224*4.  Alternately you could change the xdef/ydef lines.

Note as a quick check, your output file should be 8*8*10*4*4 (x*y*t*4) 
bytes large for that control file.

Jim

On 7/5/16 3:57 AM, Lydia Rill wrote:
> Hi all,
>
> I am a new grads user and I have never worked with binary files 
> before. I have a large binary file I created in grads (code shown 
> below). I want to split up the binary file by latitude and longitude 
> degree into smaller binary files. While this is possible in GrADS, it 
> is too slow for my needs, so I am trying to do it in Fortran 90.
>
> However, I am having problems reading the GrADS binary file in 
> Fortran. It gives me the missing value for each of my variables at 
> every time step and every location.
>
> The binary file contains NLDAS 2 forcing data, with 464 x steps, 224 y 
> steps, and 13688 daily time steps for 4 variables (only 1 Z level). It 
> is a large file at 22GB, and I can successfully display the variables 
> in GrADS from this binary file. This binary file was created from data 
> in Grib files.
>
> I have tried many various ways of reading in the binary data, using x 
> and y loops, or time loops, or looping through the 4 variables, but 
> nothing has been successful.
>
> I am working on a Mac (El Capitan).
>
> Here is the GrADS script I used to create the binary file:
>
> functionmain(args)
>
> counthr=subwrd(args,1)
>
> 'reinit'
>
> 'open /Volumes/WebData/NLDAS2/ProcessingFiles/24hours.ctl'
>
> 'set undef 9.999e20'
>
> 'set gxout fwrite'
>
> 'set fwrite -ap /Volumes/WebData/NLDAS2/DailyNLDAS/daily.bin'
>
>
> 'set t 1'
>
> t1=1+4
>
> t1p=1+5
>
> while(t1<=counthr+5-23)
>
> t2=t1+23
>
> t2p=t1p+23
>
> 'd (max(TMP2m,t='t1',t='t2')-273.15)'
>
> 'd (min(TMP2m,t='t1',t='t2')-273.15)'
>
> 'd sum(APCPsfc,t='t1p',t='t2p')'
>
> 'd (ave(DSWRFsfc,t='t1',t='t2')*24*3600/1000000)'
>
> t1=t1+24
>
> t1p=t1p+24
>
> endwhile
>
> 'quit'
>
>
> Here is the Fortran script to read the binary file
>
> ProgramReadbin
>
> implicitnone
>
> integer irec,i,j,t,days
>
> real tmin(464,224),tmax(464,224),prcp(464,224),srad(464,224)
>
> OPEN(17,file='/Volumes/WebData/NLDAS2/DailyNLDAS/daily.bin',&
>
> &STATUS='Old',FORM='UNFORMATTED',ACCESS='DIRECT',RECL=464*224*4)
>
>
> OPEN(18,file='/Volumes/WebData/NLDAS2/DailyNLDAS/testdaily.bin',&
>
> &STATUS='UNKNOWN',FORM='UNFORMATTED',ACCESS='DIRECT',RECL=464*224*4)
>
> days=10
>
> irec=1
>
> do t=1,days
>
> read(17,REC=irec) ((tmax(i,j),i=1,8),j=1,8)
>
> read(17,REC=irec+1) ((tmin(i,j),i=1,8),j=1,8)
>
> read(17,REC=irec+2) ((prcp(i,j),i=1,8),j=1,8)
>
> read(17,REC=irec+3) ((srad(i,j),i=1,8),j=1,8)
>
> write(18,REC=irec) ((tmin(i,j),i=1,8),j=1,8)
>
> write(18,REC=irec+1) ((tmin(i,j),i=1,8),j=1,8)
>
> write(18,REC=irec+2) ((prcp(i,j),i=1,8),j=1,8)
>
> write(18,REC=irec+3) ((srad(i,j),i=1,8),j=1,8)
>
>      irec=irec+4
>
> enddo
>
> end program
>
>
> The corresponding control file is:
>
> set ^testdaily.bin
>
> undef 9.999E+20
>
> title Daily NLDAS2 Data for00Z through 23Z
>
> xdef 8linear -124.93750.125
>
> ydef 8linear 25.06250.125
>
> tdef 10linear 00Z02Jan1979 1dy
>
> zdef 1linear 11
>
> vars 4
>
> TMAX 012,105,2**maximum temperature at 2m above surface [C]
>
> TMIN 011,105,2**minimum temperature at 2m above surface [C]
>
> PRCP 061,1,0**total precipitation backward accumulated [kg/m^2ormm]
>
> SRAD 0204,1,0**total surface downward shortwave radiation flux [mJ/m^2]
>
> ENDVARS
>
>
>
> Thanks,
>
> Lydia
>
> -- 
> Lydia D. Rill
> M.S., Michigan State University 2016
> B.S., Valparaiso University 2014
> (224) 406-5130
> Lydia.D.Rill at gmail.com <mailto:Lydia.D.Rill at gmail.com>
>
>
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