Code Table 4.2: new entries requested by Norway

[rmla-cz]

Branch

https://github.com/wmo-im/GRIB2/tree/issue85

Stakeholder

• MetNorway
• ECMWF

Summary and purpose

This document proposes new GRIB2 Code Table 4.2 parameters.

Action proposed

The Team is requested to review the proposed new parameter and approve it for implementation.

Discussions

The tables in this proposal contain parameters that will be of crucial importance for the Copernicus Arctic Regional Reanalysis project which has already started its production in 2020. These parameters have been widely used as GRIB1 local parameters in the HIRLAM numerical weather prediction community, and we thus believe they will be of high relevance outside the aforementioned reanalysis project.

Final Proposal

Parameter	Product Discipline	Parameter Category	Parameter number	Units
Snow evaporation rate  (see Note 8)	0	1	148	kg m-2 s-1
Surface roughness for heat (see Note 1)	0	2	47	m
Surface roughness for moisture (see Note 2)	0	2	48	m

• 0-1, 62: Snow evaporation
  • Note 8: It is recommended to use parameter 148.
• 0-1, 148: Snow evaporation rate
  • Note 9: Snow evaporation is the accumulated amount of water that has evaporated from snow from within the snow covered area of a grid-box.
• 0-2, 47: Surface roughness for heat
  • Note 1: Surface roughness for heat is a measure of the surface resistance to heat transfer.
• 0-2, 48: Surface roughness for moisture
  • Note 2: Surface roughness for moisture is a measure of the surface resistance to moisture transfer.

Initial proposal

Proposed new entry for Code Table 4.2:

Parameter	Product Discipline	Parameter Category	Parameter number	Units
Snow evaporation rate 1)	0	1	To be decided	kg m-2 s-1
Surface roughness for heat 2)	0	2	To be decided	m
Surface roughness for moisture 3)	0	2	To be decided	m

Comments:

1. Snow evaporation is the accumulated amount of water that has evaporated from snow from the snow-covered area of a grid-box. The existing parameter 62 Snow evaporation [kg m-2] should be deprecated
2. Surface roughness for heat is a measure of the surface resistance to heat transfer. It is a component of surface roughness.
3. Surface roughness for moisture is a measure of the surface resistance to moisture transfer. It is a component of surface roughness.

[sebvi]

I have been in Contact with the proposer to help them formulate their request so I assigned the issue to myself to review/validate

[sebvi]

branch updated

[jitsukoh]

@sebvi @amilan17 I confirm that this proposal is finalized and the branch is updated, and move this issue to "Validated" status.

[jitsukoh]

@sebvi sorry I should have asked you before I moved this issue to "Validated";

• could you update the original post of this issue with the parameter numbers that you used to updated the branch? This small step would save time for the Secretariat when they compile all the proposals into one document...
• could you confirm that the comments attached to the parameters will not be included in the Manual? Or are they intended to be "notes" on the PDF version on the Manual?

[amilan17]

@sebvi These are my suggestions for notes in Code Table 4.2. If these notes are intended to be published and you agree with the suggestion, please update the note_en column ("see Note X") in branch and update the original proposal with final solution. (If you cannot update the original proposal, I will do this for you.)

• 0-1, 62: Snow evaporation
  • Note 6: It is recommended to use parameter 147. 
• 0-1, 147: Snow evaporation rate 
  • Note 7: Snow evaporation is the accumulated amount of water that has evaporated from snow from within the snow covered area of a grid-box.
• 0-2, 47: Surface roughness for heat
  • Note 1: Surface roughness for heat is a measure of the surface resistance to heat transfer. It is a component of surface roughness.
• 0-2, 48: Surface roughness for moisture
  • Note 2: Surface roughness for moisture is a measure of the surface resistance to moisture transfer. It is a component of surface roughness.

[sebvi]

@amilan17 I am happy with your suggestions