[gradsusr] Fortran to Read in GrADS Binary File
Lydia Rill
lydia.d.rill at gmail.com
Tue Jul 5 13:41:04 EDT 2016
Thanks Chuck! I double checked the record length and it is indeed 4.
Thank you Jim! Sorry my code was a little messy, I have tried many
different methods.
Good point about the lower left hand corner, that was one of the issues
here.
When I use 32 x steps, 32 y steps, and 10 time steps I use a record length
of 4096 for the output file and I get a file size of 160K, which roughly
matches 32*32*10*4*4 = 16385
I am now getting realistic numbers for my output! However, when I display
the data in GrADS for one time I get only parts of the 4x4 degree box, by
latitude, for each variable, instead of getting the data for each variable
for the whole box. For example in the middle of the box I get tmax for
43.5-44N, tmin for 43-43.5N, prcp around 43N, and srad around 42.5N. Any
ideas on why this is happening?
Here is the updated code:
integer irec,i,j,t,days
character(len=100) infile,outfile
real tmin(464,224),tmax(464,224),prcp(464,224),srad(464,224)
infile='/Volumes/WebData/NLDAS2/DailyNLDAS/daily.bin'
outfile='/Volumes/WebData/NLDAS2/Fortran/testdaily.bin'
open(17,file=infile,form="unformatted",access="direct",recl=32*32*4,status=
"old")
open(18,file=outfile,form="unformatted",access="direct",recl=32*32*4,status=
"unknown")
days=10
irec=1
do t=1,days
read(17,REC=irec) ((tmax(i,j),i=129,160),j=129,160)
read(17,REC=irec+1) ((tmin(i,j),i=129,160),j=129,160)
read(17,REC=irec+2) ((prcp(i,j),i=129,160),j=129,160)
read(17,REC=irec+3) ((srad(i,j),i=129,160),j=129,160)
write(18,REC=irec) ((tmax(i,j),i=129,160),j=129,160)
write(18,REC=irec+1) ((tmin(i,j),i=129,160),j=129,160)
write(18,REC=irec+2) ((prcp(i,j),i=129,160),j=129,160)
write(18,REC=irec+3) ((srad(i,j),i=129,160),j=129,160)
irec=irec+4
enddo
Here is the updated control file:
dset ^testdaily.bin
undef 9.999E+20
title Daily NLDAS2 Data for 04Z through 03Z
xdef 32 linear -108.9375 0.125
ydef 32 linear 41.0625 0.125
tdef 10 linear 00Z02Jan1979 1dy
zdef 1 linear 1 1
vars 4
TMAX 0 12,105,2 ** maximum temperature at 2m above surface [C]
TMIN 0 11,105,2 ** minimum temperature at 2m above surface [C]
PRCP 0 61,1,0 ** total precipitation backward accumulated [kg/m^2 or mm]
SRAD 0 204,1,0 ** total surface downward shortwave radiation flux [mJ/m^2]
ENDVARS
Thank you both so much for your help,
Lydia
On Tue, Jul 5, 2016 at 12:44 PM, James T. Potemra <jimp at hawaii.edu> wrote:
> 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:
>
> function main(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
>
> Program Readbin
>
> implicit none
>
> 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 for 00Z through 23Z
>
> xdef 8 linear -124.9375 0.125
>
> ydef 8 linear 25.0625 0.125
>
> tdef 10 linear 00Z02Jan1979 1dy
>
> zdef 1 linear 1 1
>
> vars 4
>
> TMAX 0 12,105,2 ** maximum temperature at 2m above surface [C]
>
> TMIN 0 11,105,2 ** minimum temperature at 2m above surface [C]
>
> PRCP 0 61,1,0 ** total precipitation backward accumulated [kg/m^2 or mm]
>
> SRAD 0 204,1,0 ** 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
>
>
> _______________________________________________
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>
>
>
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>
--
Lydia D. Rill
M.S., Michigan State University 2016
B.S., Valparaiso University 2014
(224) 406-5130
Lydia.D.Rill at gmail.com
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