CDO

Hi Joseph,

have you read the documentation about import_binary? https://code.mpimet.mpg.de/projects/cdo/embedded/index.html#x1-7120002.14.1

-Karin

Hi Karin,

Yes, I read through the documentation on import_binary. I think I will need NCL for converting this particular type of CMORPH binary data.

Thanks kindly for your response.

Joseph

If you have the information which are needed to create the GrADS description file you should be able to use the import_binary operator.

Example grads_description_file.ctl:

DSET ^CMORPH_V1.0_ADJ_8km-30min_2018013123
OPTIONS sequential
UNDEF −9e+33
XDEF  360 LINEAR −179.5 1
YDEF  180 LINEAR −89.5 1
ZDEF  1 LINEAR 1 1
TDEF  1 LINEAR 00:00Z15jun1989 12hr
VARS  1 
param 1 99 description of the variable
ENDVARS

cdo import_binary grads_description_file.ctl outfile.bin

-Karin

Hi Karin,

Yes, there is a single ctl file:

ftp://ftp.cpc.ncep.noaa.gov/precip/CMORPH_V1.0/CTL/CMORPH_V1.0_CRT_8km-30min.ctl

and the CMORPH binaries are located here:

ftp://ftp.cpc.ncep.noaa.gov/precip/CMORPH_V1.0/CTL/CMORPH_V1.0_CRT_8km-30min.ctl

I ran the command:

cdo -b nc import_binary CMORPH_V1.0_CRT_8km-30min.ctl outfile.nc

That command produces an nc file with the lat-lon dimensions, but no other variables. I think I may be missing a step that merges the outfile.nc with the CMORPH binaries, but so far, I do not understand the next step, assuming there is one.

Other research that I've read suggests that I may need to use NCL or MATLAB to process the CMORPH binaries, but I would also like to learn how to accomplish this with CDO, if it's possible.

Thanks kindly for any assistance or ideas you may have. I'm finding CDO very useful so far, but I'm stumbling on this CMORPH binaries issue for now.

Joseph

Correction. I meant to post:

...and the CMORPH binaries are located here:

ftp://ftp.cpc.ncep.noaa.gov/precip/CMORPH_V1.0/CRT/8km-30min/2017/

The GrADS descriptor file is wrong for the given 744 files containing 2 timesteps each.

DSET ^CMORPH_V1.0_ADJ_8km-30min_%y4%m2%d2%h2
OPTIONS template little_endian
UNDEF  -999.0
TITLE  Precipitation estimates
XDEF 4948 LINEAR   0.036378335 0.072756669
YDEF 1649 LINEAR -59.963614    0.072771377
ZDEF   1 LEVELS 1
TDEF 1488 LINEAR 00Z01dec2017 30mn
VARS 1
cmorph   1  99  cmorph [ mm/hr ]
ENDVARS

After unpacking the files into a separate directory (where the descriptor file is copied, too) the following command do what it should to do

cdo -r -f nc -setreftime,2017-12-01,00:00:00,minutes -import_binary descriptor.ctl outfile.nc

Note: Take a look at the description of a GrADS descriptor file and know your data. The file names already gives you the time information you need.

-Karin

Hi Karin,

Thank you for the explanation and solution. I'm still in the process of learning the CDO commands, and your solution had not occurred to me.

Joseph