Code Table 4.1 and 4.2: new category for thermodynamical properties in discipline "land surface" and associated parameters

[sebvi]

Initial request

ECMWF is proposing a new category under discipline 2 - Land surface to encode various thermodynamical properties (heat fluxes). This requires a new entry in Code table 4.1 for the new category and a new sub-table 4.2 discipline 2, category 7

Additional, ECMWF is requesting a new parameter in code table 4.2, discipline 0, category 4

Amendment details

ADD new Category in Code Table 4.1 discipline 2 Thermodynamic properties

Code	Name
7	Thermodynamic properties

ADD new entries in Code table 4.2 discipline 2 category 7

Parameter number	name	Unit
0	Heat net flux (see Note)	[W m-2]
1	Latent heat net flux	[W m-2]
2	Sensible heat net flux	[W m-2]

Note: Heat net flux is the sum of latent heat net flux and sensible heat net flux.

ADD new entry in Code table 4.2 discipline 0 category 4

Parameter number	name	Unit
62	Direct normal short-wave radiation flux, clear sky (see note)	[W m-2]

Note: Normal flux is on a surface lifted to be normal to sun rays

ADD new entry in Code Table 4.2 discipline 0 category 19

Parameter number	name	Unit
51	Visibility through precipitation	[m]

Add new entry in Code Table 4.2 discipline 3 category 1

Parameter number	name	Unit
24	Cosine of the solar zenith angle	[Numeric]

ADD new entries to Code Table 4.2 discipline 0 category 2

Parameter number	name	Unit
68	Convective gust	[m s-1]
69	Turbulent gust	[m s-1]

Comments

No response

Requestor(s)

Sebastien Villaume (ECMWF)
Matthew Griffith (ECMWF)

Stakeholder(s)

ECMWF
EU - Destination Earth programme

Publication(s)

Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.1 (update)
Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 0, category 4 (update)
Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 2, category 7 (new subtable)

Expected impact of change

LOW

Collaborators

No response

References

No response

Validation

No response

[sebvi]

I have just added parameters that were forgotten

[sebvi]

branch created and updated

[amilan17]

https://github.com/wmo-im/CCT/wiki/Teleconference.2.July.2024 notes:
Sebastien introduced the proposal; there was discussion about the "Cosine of the SZA" parameter, but team agrees to proposal in general; @sebvi and @SibylleK check with colleagues on the requirements for cosine;

[amilan17]

@sebvi the note is missing - it is referenced in Code table 4.2 discipline 2 category 7, but I don't see a note in the proposal nor the branch

[SibylleK]

Maybe note (1) "By convention, the flux sign is positive if downwards" of Code table 4.2 is meant here.

In any case, I received a corresponding note from my colleague, that it would be good to clarify, that this note is also valid for these surface fluxes.

Another comment is, to consider to define these new entries as ".. total flux", as in future you might be able to diffferentiate between e.g. "due to exaporation" and "due to sublimation".

[mjg41]

Apologies the Note got lost somewhere along the way, it was intended to be:

Note: Heat net flux is the sum of latent heat net flux and sensible heat net flux

The new entry 62 in Code table 4.2 discipline 0 category 4 should also be linked to Note ID 69.

Many thanks.

[amilan17]

@sebvi @mjg41 Is this the correct note for entry 62?

Parameter number	name	Unit
62	Direct normal short-wave radiation flux, clear sky	[W m-2]

69,Normal flux is on a surface lifted to be normal to sun rays.

[amilan17]

Another comment is, to consider to define these new entries as ".. total flux", as in future you might be able to diffferentiate between e.g. "due to exaporation" and "due to sublimation".

@SibylleK @sebvi does this need discussion? if so -- we cannot include this proposal in FT2024-2.

[sebvi]

parameters in Code Tables 4.2..0.4 and 4.2.0.5 don't specify "total" when it is assumed total so I would not make these parameters different for consistency.

[amilan17]

it was determined through email that it's not necessary to revise this proposal further.