New parameters in Code Table 4.2

[sebvi]

Initial request

The parameter “Live fuel moisture content” (discipline=2, parameter category=4, parameter number =31) can be subdivided into a component for low and high vegetation. We propose to add these two additional entries.

The Obukhov Length (L) is a well-established parameter in boundary layer meteorology. We propose to add the reciprocal Obukhov length (1/L) because L can be infinite in certain cases of neutral stability.

ECMWF is also requesting a set of ocean parameters needed for our latest development so that more of the ocean output portfolio can be made available in GRIB. Note that due to the organisation of the oceanography discipline, we need to request the same parameter in 3 different categories.

Amendment details

ADD to code table 4.2: Product discipline 2 , parameter category 4

Code	Description	Unit
37	Live fuel moisture content in low vegetation	kg kg-1
38	Live fuel moisture content in high vegetation	kg kg-1

ADD to code table 4.2: Product discipline 0 , parameter category 7

Code	Description	Unit
21	Reciprocal Obukhov length	m-1

ADD to Code table 4.2: Product discipline 0, parameter category 4

Code	Description	Unit
63	Diffuse short-wave radiation flux, clear sky	W m-2

ADD to code table 4.2: Product discipline 10, parameter category 2

Code	Description	Unit
30	Downward short-wave radiation flux	W m-2

ADD to code table 4.2: Product discipline 10, parameter category 3

Code	Description	Unit
22	Downward short-wave radiation flux	W m-2

ADD to code table 4.2: Product discipline 10, parameter category 4

Code	Description	Unit
52	Sea water upward volume transport	m3 m-2 s-1
53	Sea water upward mass transport	kg m-2 s-1
54	Sea water age since surface contact	s
55	Sea water downward short-wave radiation flux	W m-2

Comments

No response

Requestor(s)

Sebastien Villaume (ECMWF) 
Robert Osinski (ECMWF) 
Matthew Griffith (ECMWF) 

Stakeholder(s)

ECMWF

Publication(s)

Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 2, category 4 (update) 
Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 0, category 7 (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 10, category 3 (update)
Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 10, category 3 (update)
Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2, discipline 10, category 4 (update)

Expected impact of change

None

Collaborators

No response

References

No response

Validation

No response

[amilan17]

https://github.com/wmo-im/tt-tdcf/wiki/2024.11.12.tt.tdcf notes:

• Sebastien introduced the proposal
• these parameters have been encoded in NetCDF and the NEMO ocean model at ECMWF
• Sibylle suggested adding a new category under discipline 10 instead of repeating parameters in multiple categories

[amilan17]

https://github.com/wmo-im/tt-tdcf/wiki/2024.11.12.tt.tdcf notes:
Matthew explained the problem with adding a new category would require deprecation of the other parameters; Sibylle noted that it would be better to add a note to use the values in the new category instead because this would set a better practice; Jeff noted that the combination of discipline/category/parameter defines the uniqueness of the parameter;

• need comments from the ocean community on the repetition of parameters across different 4.2 tables before 20 December: @david-i-berry and Matthew will reach out to NEMO