Adding station ident to columns in SYNOP and TEMP readers

[martin-janousek-ecmwf]

Is your feature request related to a problem? Please describe.

BUFR data archived at ECMWF have a station attribute "ident" which is either a "traditional" 7-character numeric string (e.g. 11520) or (for newer stations which have only WIGOS ids) a fake-ID, assigned by ECMWF, typically starting with the underscore. We have been using the ident for internal software systems (verification) and it would be therefore vital pdbufr.read_bufr also provide it.

Describe the solution you'd like

A new column "ident" (or any other name) to be implemented in read_bufr.

Describe alternatives you've considered

No response

Additional context

As a reference the geopoints object retruned by metview.bufr_filter returns in the station id column the content of "ident" attribute.

Organisation

ECMWF

[sandorkertesz]

@martin-janousek-ecmwf, thanks for this proposal. Can I assume that context is the "synop" reader only?

[martin-janousek-ecmwf]

@sandorkertesz, at this point yes, we are trying to use pdbufr for decoding SYNOP. But if in the future we move to pdbufr from metview.bufr_filter with TEMP data decoding as well, we will need "ident" column for "temp" as well. Thank you.

[sandorkertesz]

At the moment the stnid parameter for a given BUFR message/subset in the synop and temp readers are generated from the following keys. They are all tried in the given order and the first one that has a value will be the stnid.

• WMO_station_id
• WIGOS_station_id
• shipOrMobileLandStationIdentifier
• station_id
• icaoLocationIndicator
• stationOrSiteName

Option 1

One idea is to add a new kwarg e.g. stnid_keys to these readers, which would define all the BUFR keys that should be tried in the given order to generate the stnid. The default would be the list above. E.g. using `stnid_keys="ident" would only use the "ident" key alone.

Option 2

Add "ident" as an optional station parameter like "name". Could be used like this e.g.

read_bufr(data, reader="synop", columns=["station", "ident", "t2m"])

Result:

      stnid       lat            lon             elevation          time            ident              t2m 
0  91948  -23.13017    -134.96533       91.0      2020-03-15    91948           300.45
...

[martin-janousek-ecmwf]

For my use case the option 1 seems optimal as I will even get the station ID in the column named the same way as by metview. The only disadvantage of this option is could see would be when someone would like to see both ident and e.g. WIGOS_station_id.

[sandorkertesz]

@martin-janousek-ecmwf, "ident" is now the first key to try to generate "stnid" and the "stnid_keys" option was also added (see: #98)

These are already available in version 0.14.0.