New Parameter entries in Code table 4.2 for Copernicus and Destination Earth projects.

[sebvi]

Initial request

[to be added]

Amendment details

ADD in Code Table 4.2, in the correct disciplines and categories:

discipline 0, category 1

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Column integrated divergence of total water mass flux	0	1	165	kg m-2 s-1
Column integrated water vapour flux	0	1	166	kg m-1 s-1
Total column supercooled liquid water	0	1	167	kg m-2

discipline 0, category 2

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Natural logarithm of surface roughness length for heat	0	2	54	Numeric
Natural logarithm of surface roughness length for moisture	0	2	55	Numeric
u-component of neutral wind	0	2	56	m s-1
v-component of neutral wind	0	2	57	m s-1
Magnitude of turbulent surface stress	0	2	58	N m-2

discipline 0, category 3

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Standard deviation of filtered subgrid orography	0	3	38	m
Column integrated mass of atmosphere	0	3	39	kg m-2
Column integrated eastward geopotential flux	0	3	40	W m-1
Column integrated northward geopotential flux	0	3	41	W m-1
Column integrated divergence of water geopotential flux	0	3	42	W m-2
Column integrated divergence of geopotential flux	0	3	43	W m-2
Height of zero-degree wet-bulb temperature	0	3	44	m
Height of one-degree wet-bulb temperature	0	3	45	m

discipline 0, category 4

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
UV visible albedo for diffuse radiation	0	4	55	%
UV visible albedo for direct radiation	0	4	56	%
UV visible albedo for direct radiation, geometric component	0	4	57	%
UV visible albedo for direct radiation, isotropic component	0	4	58	%
UV visible albedo for direct radiation, volumetric component	0	4	59	%
Photosynthetically active radiation flux, clear sky	0	4	60	W m-2
Direct short-wave radiation flux, clear sky	0	4	61	W m-2

discipline 0, category 5

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Near IR albedo for diffuse radiation	0	5	9	%
Near IR albedo for direct radiation	0	5	10	%
Near IR albedo for direct radiation, geometric component	0	5	11	%
Near IR albedo for direct radiation, isotropic component	0	5	12	%
Near IR albedo for direct radiation, volumetric component	0	5	13	%

discpline 0, category 6

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Sunshine duration fraction (see Note)	0	6	51	Proportion

Note: This parameter is the amount of sunshine in seconds over a given length of time in seconds. Sunshine is defined as a radiation intensity above 120 W m-2

discipline 0, category 19

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Duct base height (see Note 1)	0	19	41	m
Trapping layer base height (see Note 1)	0	19	42	m
Trapping layer top height (see Note 1)	0	19	43	m
Mean vertical gradient of refractivity inside trapping layer (see Note 1)	0	19	44	m-1
Minimum vertical gradient of refractivity inside trapping layer (see Note 1)	0	19	45	m-1

Note 1: A duct layer is an atmospheric layer with a refractivity which leads to a trapping of electromagnetic waves. In a trapping layer the refractivity leads to a bending of EM waves, which is stronger than the earth’s curvature.

discipline 0, category 21

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Column integrated eastward heat flux	0	21	19	W m-1
Column integrated northward heat flux	0	21	20	W m-1
Column integrated potential+internal+latent energy	0	21	21	J m-2

discipline 2, category 0

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Skin reservoir content	2	0	50	kg m-2
Surface runoff rate	2	0	51	kg m-2 s-1
Sub-surface runoff rate	2	0	52	kg m-2 s-1
Low vegetation cover	2	0	53	Proportion
High vegetation cover	2	0	54	Proportion
Leaf area index, low vegetation	2	0	55	m2 m-2
Leaf area index, high vegetation	2	0	56	m2 m-2
Type of low vegetation	2	0	57	Code table 4.234
Type of high vegetation	2	0	58	Code table 4.234
Net ecosystem exchange flux (see Note 1)	2	0	59	kg m-2 s-1
Gross primary production flux (see Note 1)	2	0	60	kg m-2 s-1
Ecosystem respiration flux (see Note 1)	2	0	61	kg m-2 s-1

Note 1: This parameter can be used with templates for chemical constituents to specify a chemical species if needed, for instance: Net ecosystem CO2 exchange flux or Net ecosystem CH4 exchange flux

discipline 3, category 1

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Reflectance in 0.4 micron channel	3	1	30	%

discipline 10, category 0

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Mean wave period based on first moment	10	0	74	s
Mean wave period based on first moment for swell	10	0	75	s
Mean wave period based on first moment for wind waves	10	0	76	s
Mean wave period based on second moment for swell	10	0	77	s~~
Mean wave period based on second moment for wind waves	10	0	78	s
Mean direction of total swell	10	0	79 74	degrees
Mean direction of wind waves	10	0	80 75	degrees
Charnock (see Note 1)	10	0	81 76	Numeric
Wave Spectral Skewness	10	0	82 77	Numeric
Wave energy flux magnitude	10	0	83 78	W m-1
Wave energy flux mean direction	10	0	84 79	Degree true
Ratio of wave angular and frequency width	10	0	85 80	Numeric
Free convective velocity over the oceans	10	0	86 81	m s-1
Air density over the oceans	10	0	87 82	kg m-3
Normalized energy flux into waves (see Note 2)	10	0	88 83	Numeric
Normalized stress into ocean (see Note 2)	10	0	89 84	Numeric
Normalized energy flux into ocean (see Note 2)	10	0	90 85	Numeric
Surface elevation variance due to waves (over all frequencies and directions)	10	0	91 86	m2 s rad-1

Note 1: The Charnock parameter accounts for increased aerodynamic roughness as wave heights grow due to increasing surface stress. It depends on the wind speed, wave age and other aspects of the sea state and is used to calculate how much the waves slow down the wind.
Note 2: Parameters are normalised by being divided by the product of air density and the square of the friction velocity.

discipline 10, cateogry 3

Parameter	Product Discipline	Parameter Category	proposed Parameter number	Units
Deviation of sea level from mean with inverse barometer correction	10	3	20	m

Comments

No response

Requestor(s)

Matthew Griffith, Robert Osinski and Sebastien Villaume (all ECMWF)

Stakeholder(s)

ECMWF
Copernicus program
Destination Earth program

Publication(s)

Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.2

Expected impact of change

No response

Collaborators

No response

References

No response

Validation

No response

[sebvi]

This proposal is particularly long, I could split it into smaller chunks.

[amilan17]

https://github.com/wmo-im/CCT/wiki/Teleconference-1-and-2.11.2022 notes:

@SibylleK provided comments. Add notes for sunshine duration fraction, duct base and trapping layer. Add hypen to high/low vegetation. Rephrase 'Charnock' to something more meaningful. Add note for normalized * (normalized by what?). Clarify meaning of 'over the oceans' or is it needed?

[amilan17]

https://github.com/wmo-im/CCT/wiki/Teleconference-21.11.2022 notes:
(@sebvi) reviewing comments and will update issue and branch

[sebvi]

!!! REMOVED. the following parameters from the proposal: !!!
Mean wave period based on first moment 10 0 74 s
Mean wave period based on first moment for swell 10 0 75 s
Mean wave period based on first moment for wind waves 10 0 76 s
Mean wave period based on second moment for swell 10 0 77 s
Mean wave period based on second moment for wind waves 10 0 78 s

"Mean wave period based on first moment" is already defined as "inverse mean wave frequency"
"Mean wave period based on second moment" is already defined as "mean zero-crossing period"
These are alternative naming definitions that make sense if you are dealing with waves according to our in-house expert so the parameters we were proposing are already defined in

Inverse mean wave frequency 10 0 25 s
Inverse mean frequency of wind waves 10 0 26 s
Inverse mean frequency of total swell 10 0 27 s
Mean zero-crossing period of wind waves 10 0 29 s
Mean zero-crossing period of total swell 10 0 30 s

[sebvi]

Response to comments formulated by @SibylleK and DWD:

• Maybe a more “orthogonal” and flexible alternative to entries:
  “Height of zero-degree wet-bulb temperature 0 3 44 m”
  “Height of one-degree wet-bulb temperature 0 3 45 m”

could be already existing:

“Geometric height 0 3 6 m”
and a new entry in Code Table 4.5 – Fixed surface types and units:
“Level of specified web-bulb temperature K (or °C instead?)”

After discussing with our expert, it does not seem that we will ever produce this with other values of wet bulb temperature so it feels a bit overkill to create a new type of Fixed surface for this purpose. Instead of 2 parameters in code tables, we would have 1 parameter in it and 1 entry in Code table 4.5 .

-Regarding New entry:
“Sunshine duration fraction 0 6 51 Proportion”
The following entries do already exist:
“Sunshine 0 6 24 Numeric”
“Sunshine duration 0 6 33 s”

Maybe one could add a Note for the new entry to explain: “fraction” of what?
For instance: “Note xyz: Sunshine duration fraction of local length of day(?)“.

This sunshine concept is tricky. Strictly speaking the sunshine duration parameter in seconds is the amount of seconds over a period of time when the radiation intensity is above 120 W/m2 . My understanding is that 0/6/24 is the instantaneous radiation: at a given time t, if the downward radiation is above 120 W/m-2 then the parameter is 1 otherwise it is 0. Then if you accumulate this over a period a time, and your delta t is 1 seconds, it is the number of seconds in the time interval where radiation is over or equal to 120 W/m-2. Strictly speaking 0/6/33 could be encoded as 0/6/24 + accum key and should then be deprecated. Now our new parameter is different, it is a fraction so in a sense it is the accumulation in seconds I just described divided by the overall size of the accumulation window in seconds. For instance 2468 seconds of sunshine during the last hour is 2468/3600 = 0.6855555 . Does it makes sense?

• New entries in discipline 0, category 19: What do “Duct” and “Trapping layer” mean? Maybe add a Note for non-experts?

A duct layer is an atmospheric layer with a refractivity which leads to a trapping of electromagnetic waves. In a trapping layer the refractivity leads to a bending of EM waves, which is stronger than the earth’s curvature.

• How does the new entry:
  “Surface runoff rate 2 0 51 kg m-2 s-1”
  compare with the existing entry:
  “Water runoff and drainage rate 2 0 42 kg m-2 s-1”?

"Water runoff and drainage rate” includes the drainage rate while “surface runoff rate” does not.

• The description of the following new entry:
  “Charnock 10 0 81 Numeric”
  could be a bit more detailed. Maybe “Charnock xyz parameter/coefficient”?

Not sure I understand the comment. Charnock is roughness over water, what else should be specify?

• The new entries containing “… over the oceans”: What does that mean? Does it refer to an air layer directly above the water surface, which has to be specified by first and second fixed surfaces?

Parameters containing "over the oceans" are only calculated over water bodies represented in the ocean wave model. It is interpolated from the atmospheric model horizontal grid onto the horizontal grid used by the ocean wave model.

• The new entries containing “Normalized …”: Should there be a Note to clarify the question: “Normalized” by what?

Parameters are normalised by being divided by the product of air density and the square of the friction velocity.

[amilan17]

https://github.com/wmo-im/CCT/wiki/Teleconference-12-and-13.12.2022 notes:

sebastien posted answers to questions (in comment above), updated the proproposal to indicate changes. @sebvi will add notes to the issue summary and add note for Charnock. @SibylleK will review the feedback and updated proposal.

[sebvi]

branch updated with new wave parameter numbering, added a parameter that was missing (last one of the list) and added all the notes we discussed

[amilan17]

https://github.com/wmo-im/CCT/wiki/Teleconference-10.01.2023 notes:

@SibylleK double check the changes and then tag @amilan17 or @marijanacrepulja when complete