Phenomenon translation

iris-grib attempts to translate between CF phenomenon identities (i.e. ‘standard_name’ and possibly ‘long_name’ attributes), and GRIB parameter codes, when converting cubes to or from the GRIB format.

A set of tables define known CF translations for GRIB1 and GRIB2 parameters, and can be interrogated with the functions in iris_grib.grib_phenom_translation.

Parameter loading record

All cubes loaded from GRIB have a GRIB_PARAM attribute, which records the parameter encodings present in the original file message.

Examples :

• "GRIB2:d000c003n005" represents GRIB2, discipline=0 (“Meteorological products”), category=3 (“Mass”) and indicatorOfParameter=5 (“Geopotential height (gpm)”).

  • This translates to a standard_name and units of “geopotential_height / m”

• "GRIB1:t002c007n033" is GRIB1 with table2Version=2, centre=7 (“US National Weather Service - NCEP (WMC)”), and indicatorOfParameter=33 (“U-component of wind m s**-1”).

  • This translates to a standard_name and units of “x_wind / m s-1”.

Parameter saving control

When a cube has a GRIB_PARAM attribute, as described above, this controls what the relevant message keys are set to on saving. (N.B. at present applies only to GRIB2, since we don’t support GRIB1 saving)