2022-11-30 ODE DT output portfolio SURFEX to GRIB2

Date

30 Nov 2022

Attendees

Matthew Griffith
Sebastien Villaume
Søren Borg Nielsen (DMI)
Ulf Andrae (SHMI)

Apologies

Richard Mladek

Goals

Meeting to discuss how to implement SURFEX tile variables in GRIB2 (see Tiles handling in GRIB 2 for some background)

Discussion items

Item	Who	Notes
Current state of play	All	The current WMO templates proposed by DWD (Code Template 4.55, Code Template 4.59) "spatio-temporal changing tiles" are not really ideal for SURFEX tile classifications - they rely on a local nomenclature for tile numbering. But these could be useful for an initial prototyping and to help discover how this type of GRIB2 template works. Other WMO templates which accomplish this tile division (Code Template 4.53, Code Template 4.54) "partitioned parameters" require a fixed set of tiles which cannot vary in time and must always have a corresponding GRIB message.
Timelines	All	Apr 2024 deadline for outputting SURFEX variables for DestinE, with pre-operational testing required in Nov 2023. If we want a new WMO template we should have this by March 2023 for WMO proposal, which should be in place by end of Q2 in pre-production and then published officially in November 2023.
Future	All	The ideal would be to have some fusion of the two types of templates above, where (for example) Code Table 4.243 is used to classify the tiles rather than a local nomenclature. We agreed that in the first instance, it would be good to look over output files which use Code Template 4.55 to get an idea for what we might want to propose as a new template. Matt will provide an example of data which uses Template 4.55.

After some investigation, I found some DWD output which uses Code Template 4.53 - see attached grib2 file here. Hopefully this is useful while I look to see if I can find something for Code Template 4.55

As well as this, I attach the Annex to the WMO Manual on Codes which describes the Code Template 4.55/4.56 and its difference to Code Template 4.53/4.54 - see the attached pdf file here.

Update: I have found a sample file which uses Code Template 4.55 - see attached grib2 file here. I got this by chatting with Sebastian Borchert. He says this template is rather cumbersome and would create significant support overhead, so it is good that we are investigating an alternative.

Action items

Give a sample GRIB2 file which uses Code Template 4.55: Matthew Griffith
Decide on what types of tiles are needed within SURFEX: Søren Borg Nielsen & Ulf Andrae
Schedule next meeting: 14/12/2022, 9am GMT: Matthew Griffith

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