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Description

For the projects like projects  TIGGE, S2S or and UERRA the exact data format, WMO compliant GRIB2 in those cases,  is required to allow easy data processing and intercomparison. To check that the encoding is as requested, one can use tigge_check tool which is a part of ecCodes package.

The tigge_check can do also very some basic quality control by checking the allowed value ranges for each parameter (with -v option) . Some allowed ranges can become obsolete at some point e.g. due to model upgrade to higher resolution meaning in general different values of some parameters.  if they were defined. There is another newer better maintainable tool doing similar basic quality check called grib_check.py. Read more information about both tools in Data quality checking tools (python source code is available there).

There is a further tool grib_enc_check.py which is used for data encoding check of more recent project LC-WFV  (Lead Centre for Wave Forecast Verification). The encoding checking is not as comprehensive as in tigge_check e.g. geometry checks are missing completely.

Examples of tigge_check usage

tigge_check options

$ tigge_check
tigge_check [options] grib_file grib_file ...
   -l: check local area model fields
   -v: check value ranges
   -w: warnings are treated as errors
   -g: write good gribs
   -b: write bad  gribs
   -z: return 0 to calling shell
   -s: check s2s fields
   -r: check s2s reforecast fields
   -u: check uerra fields

Checking UERRA data

Checking S2S reforecast data

Examples of grib_enc_check.py usage

grib_enc_check.py options

# BIN=/home/ma/emos/def/lcwfv/bin
python $BIN/grib_enc_check.py         
usage: grib_enc_check.py [-h] [-v VERBOSITY] [-d DEFS]
                         [inp_file [inp_file ...]]

positional arguments:
  inp_file              enter input file name(s)

optional arguments:
  -h, --help            show this help message and exit
  -v VERBOSITY, --verbosity VERBOSITY
                        increase output verbosity [0-2]
  -d DEFS, --defs DEFS  path to definition files

Checking LC-WVF data

$BIN/grib_enc_check.py lw.grib2
 field 223(Mean wave direction) key: dataRepresentationTemplateNumber expected: <0..2> encoded: 40
 field 224(10 metre U wind component) key: dataRepresentationTemplateNumber expected: <0..2> encoded: 40
Number of error(s) found: 2

Performance tip to speed up checking big files 

There is a new tool  (ecCodes v>=2.6.0) called codes_split_file which is useful for parallellising decoding/checking tasks like tigge_check.

NAME    codes_split_file
DESCRIPTION
        Split an input file (GRIB, BUFR etc) into chunks of roughly the same size.

        The output files are named input_1, input_2 etc. This is much faster than grib_copy/bufr_copy.
USAGE
        codes_split_file [-v] nchunks input
OPTIONS
        -v  Print the count of messages and files created

If one has a very large input file with 1000s of messages, instead of running one process which sequentially checks each message in the file, one can split the file into 8 chunks and run the checking code in parallel on the 8 output files.

set -e

# Assume you have 8 cores
codes_split_file 8 my_big.grib

# Now you will have my_big.grib_01, my_big.grib_02, ... my_big.grib_08
for f in my_big.grib_*; do
  # Run check in the background. Now multiple processes are running in parallel
  tigge_check $f &
done

# With the 'wait' command you can force the execution of the script to pause until a
# all background jobs have finished executing before continuing the execution
# of your script
wait

# Now clean up the split files
rm -f my_big.grib_*

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