Grib with 3.12 grid not loading

[Karl De Vine]

Hi,

Am fairly new to iris and have some grib2 files with 3.12 transverse mercator projection which I'm unable to load:

iris.exceptions.TranslationError: Grid definition section 3 contains unsupported source of grid definition [12]

This is with Iris 2.2.0 . Similar error occurs with iris_grib.

Can someone please point me in the right direction with these files. Not keen on building a custom loader.

Thanks
Karl

[Klaus Zimmermann]

Hi Karl,

could you share the whole stacktrace with us?

That would really help pin it down.

Cheers
Klaus

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[Karl De Vine]

thanks for looking

 

>>> levels=iris.load("201902251200_u1096_ng_umqv_Wholesale1.grib")

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/root/miniconda3/lib/python2.7/site-packages/iris/__init__.py", line 343, in load

    return _load_collection(uris, constraints, callback).merged().cubes()

  File "/root/miniconda3/lib/python2.7/site-packages/iris/__init__.py", line 313, in _load_collection

    result = iris.cube._CubeFilterCollection.from_cubes(cubes, constraints)

  File "/root/miniconda3/lib/python2.7/site-packages/iris/cube.py", line 145, in from_cubes

    for cube in cubes:

  File "/root/miniconda3/lib/python2.7/site-packages/iris/__init__.py", line 300, in _generate_cubes

    for cube in iris.io.load_files(part_names, callback, constraints):

  File "/root/miniconda3/lib/python2.7/site-packages/iris/io/__init__.py", line 210, in load_files

    for cube in handling_format_spec.handler(fnames, callback):

  File "/root/miniconda3/lib/python2.7/site-packages/iris/fileformats/rules.py", line 429, in load_cubes

    user_callback_wrapper=loadcubes_user_callback_wrapper):

  File "/root/miniconda3/lib/python2.7/site-packages/iris/fileformats/rules.py", line 350, in _load_pairs_from_fields_and_filenames

    cube, factories, references = _make_cube(field, converter)

  File "/root/miniconda3/lib/python2.7/site-packages/iris/fileformats/rules.py", line 293, in _make_cube

    metadata = converter(field)

  File "/root/miniconda3/lib/python2.7/site-packages/iris_grib/_load_convert.py", line 2515, in convert

    grib2_convert(field, metadata)

  File "/root/miniconda3/lib/python2.7/site-packages/iris_grib/_load_convert.py", line 2464, in grib2_convert

    grid_definition_section(field.sections[3], metadata)

  File "/root/miniconda3/lib/python2.7/site-packages/iris_grib/_load_convert.py", line 1247, in grid_definition_section

    raise TranslationError(msg)

[Klaus Zimmermann]

Hi Karl,

thanks, that helps to locate the problem.

In general, iris always reads grib data via iris_grib, the two are not
separate projects.

Unfortunately, I think what you are looking for actually is a missing
feature of iris_grib.

I saw that you opened the new issue #140 and I think that is exactly the
right thing to do. Let's hope somebody can find the time to implement it.

One tip for the issue: if you surround the header with a leading blank
line and a triple backtick(`) ala

```
Grib header is:
#============== MESSAGE 1 ( length=434207 ) ==============
GRIB {
# Meteorological products (grib2/tables/4/0.0.table)

discipline = 0;
editionNumber = 2;
# U.K. Met Office - Exeter (common/c-11.table)
...
```

the formatting is much clearer.

Let's continue the discussion in the ticket.

Cheers
Klaus