New section 4 Templates to encode wave parameters

[sebvi]

Initial request

The following two templates are available for GRIB2 to encode wave parameters selected by their wave period range

Code	Description
103	Analysis or forecast at a horizontal level or in a horizontal layer at a point in time for waves selected by period range
104	Individual ensemble forecast control and perturbed at a horizontal level or in a horizontal layer at a point in time for waves selected by period range

To be able to encode temporal statistics of these parameters (mean, maximum, minimum, etc.), we propose new templates based on the templates 103 and 104 and adding the following entries, relevant to encode temporal processing:

Number of octets	Description
2	Year of end of overall time interval
1	Month of end of overall time interval
1	Day of end of overall time interval
1	Hour of end of overall time interval
1	Minute of end of overall time interval
1	Second of end of overall time interval
1	n - number of time range specifications describing the time intervals used to calculate the statistically processed field
4	Total number of data values missing in statistical process
	Specification of the outermost (or only) time range over which statistical processing is done
1	Statistical process used to calculate the processed field from the field at each time increment during the time range (see code table 4.10)
1	Type of time increment between successive fields used in the statistical processing (see code table 4.11)
1	Indicator of unit of time for time range over which statistical processing is done (see code table 4.4)
4	Length of the time range over which statistical processing is done, in units defined by the previous octet
1	Indicator of unit of time for the increment between the successive fields used (see code table 4.4)
4	Time increment between successive fields, in units defined by the previous octet
	Following octets are included only if n > 1 and repeated n-1 times
12	next innermost step of processing (12 octets)

Amendment details

ADD to code table 4.0 Product definition template number

Code	Description
144	Analysis or forecast at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval for waves selected by period range
145	Individual ensemble forecast, control and perturbed, at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval for waves selected by period range

ADD TEMPLATE 4.144, Analysis or forecast at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval for waves selected by period range

Octet	Number of Octets	Description
10	1	Parameter Category (see code table 4.1)
11	1	Parameter Number (see code table 4.2)
12	1	Type of Wave Period Interval (see code table 4.91)
13	1	Scale Factor of Lower Wave Period Limit
14-17	4	Scaled Value of Lower Wave Period Limit
18	1	Scale Factor of Upper Wave Period Limit
19-22	4	Scaled Value of Upper Wave Period Limit
23	1	Type of Generating Process (see code table 4.3)
24	1	Background Process
25	1	Generating Process Identifier
26-27	2	Hours After Data Cut-off
28	1	Minutes After Data Cut-off
29	1	Indicator of Unit of Time Range (see code table 4.4)
30-33	4	Forecast Time
34	1	Type of First Fixed Surface (see code table 4.5)
35	1	Scale Factor of First Fixed Surface
36-39	4	Scaled Value of First Fixed Surface
40	1	Type of Second Fixed Surface (see code table 4.5)
41	1	Scale Factor of Second Fixed Surface
42-45	4	Scaled Value of Second Fixed Surface
46-47	2	Year of end of overall time interval
48	1	Month of end of overall time interval
49	1	Day of end of overall time interval
50	1	Hour of end of overall time interval
51	1	Minute of end of overall time interval
52	1	Second of end of overall time interval
53	1	n - number of time range specifications describing the time intervals used to calculate the statistically processed field
54-57	4	Total number of data values missing in statistical process
		58 - 69 Specification of the outermost (or only) time range over which statistical processing is done
58	1	Statistical process used to calculate the processed field from the field at each time increment during the time range (see code table 4.10)
59	1	Type of time increment between successive fields used in the statistical processing (see code table 4.11)
60	1	Indicator of unit of time for time range over which statistical processing is done (see code table 4.4)
61-64	4	Length of the time range over which statistical processing is done, in units defined by the previous octet
65	1	Indicator of unit of time for the increment between the successive fields used (see code table 4.4)
66-69	4	Time increment between successive fields, in units defined by the previous octet
		70 - nn These octets are included only if n > 1, where nn = 58+ 12 x n
70-81	12	As octets 58 to 69, next innermost step of processing
82-nn	n/a	Additional time range specifications, included in accordance with the value of n. Contents as octets 58 to 69, repeated as necessary

ADD TEMPLATE 4.145, Individual ensemble forecast, control and perturbed, at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval for waves selected by period range

Octet	Number of Octets	Description
10	1	Parameter Category (see code table 4.1)
11	1	Parameter Number (see code table 4.2)
12	1	Type of Wave Period Interval (see code table 4.91)
13	1	Scale Factor of Lower Wave Period Limit
14-17	4	Scaled Value of Lower Wave Period Limit
18	1	Scale Factor of Upper Wave Period Limit
19-22	4	Scaled Value of Upper Wave Period Limit
23	1	Type of Generating Process (see code table 4.3)
24	1	Background Process
25	1	Generating Process Identifier
26-27	2	Hours After Data Cut-off
28	1	Minutes After Data Cut-off
29	1	Indicator of Unit of Time Range (see code table 4.4)
30-33	4	Forecast Time
34	1	Type of First Fixed Surface (see code table 4.5)
35	1	Scale Factor of First Fixed Surface
36-39	4	Scaled Value of First Fixed Surface
40	1	Type of Second Fixed Surface (see code table 4.5)
41	1	Scale Factor of Second Fixed Surface
42-45	4	Scaled Value of Second Fixed Surface
46	1	Type of Ensemble Forecast (see code table 4.6)
47-50	4	Perturbation Number
51-54	4	Number of Forecasts in Ensemble
55-56	2	Year of end of overall time interval
57	1	Month of end of overall time interval
58	1	Day of end of overall time interval
59	1	Hour of end of overall time interval
60	1	Minute of end of overall time interval
61	1	Second of end of overall time interval
62	1	n - number of time range specifications describing the time intervals used to calculate the statistically processed field
63-66	4	Total number of data values missing in statistical process
		67 - 78 Specification of the outermost (or only) time range over which statistical processing is done
67	1	Statistical process used to calculate the processed field from the field at each time increment during the time range (see code table 4.10)
68	1	Type of time increment between successive fields used in the statistical processing (see code table 4.11)
69	1	Indicator of unit of time for time range over which statistical processing is done (see code table 4.4)
70-73	4	Length of the time range over which statistical processing is done, in units defined by the previous octet
74	1	Indicator of unit of time for the increment between the successive fields used (see code table 4.4)
75-78	4	Time increment between successive fields, in units defined by the previous octet
		79 - nn These octets are included only if n > 1, where nn = 67+ 12 x n
79-90	12	As octets 67 to 78, next innermost step of processing
91-nn	n/a	Additional time range specifications, included in accordance with the value of n. Contents as octets 67 to 78, repeated as necessary

Comments

No response

Requestor(s)

Sebastien Villaume (ECMWF)
Robert Osinski (ECMWF)

Stakeholder(s)

ECMWF

Publication(s)

Manual on Codes (WMO-No. 306), Volume I.2, GRIB code table 4.0 (update) 
Manual on Codes (WMO-No. 306), Volume I.2, GRIB Template 4.144 (create) 
Manual on Codes (WMO-No. 306), Volume I.2, GRIB Template 4.145 (create)

Expected impact of change

None

Collaborators

No response

References

No response

Validation

No response

[amilan17]

https://github.com/wmo-im/tt-tdcf/wiki/2024.11.13.tt.tdcf notes:

• Sebastien introduced the proposal
• @sebvi add samples
• @SibylleK validate

[sebvi]

Please find attached some sample files and a version of ecCodes capable of encode/decode the new proposed templates.
FT2025-1_284.tar.gz
eccodes-2.40.0-Source.tar.gz

[amilan17]

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

• @sebvi branch is ready to update

[sebvi]

branch is updated

[amilan17]

https://github.com/wmo-im/et-data/wiki/2025.01.14.et.data notes:
@SibylleK will validate soon; Robert can upload an ec dump

[rdosinski]

Please find attached ASCII files with section 4 grib_dumps as discussed in the meeting from 14/01/2025 :
dumps_284.tar.gz

In the template 145, there is the small 1 byte ensemble size defined:
47 | 1 | Perturbation Number
48 | 1 | Number of Forecasts in Ensemble

The samples include a 4 byte ensemble size.
@sebvi, please update the description and git branch accordingly to
47-50 | 4 | Perturbation Number
51-54 | 4 | Number of Forecasts in Ensemble
and add 6 bytes to the following entries.

[SibylleK]

@sebvi or @rdosinski could you also update the samples. In the provided GRIB examples it seems, that discipline category and parameter number is 0 and the overall time interval is 23.3.2007 12:00.:00.
The examples of the dumps are most likely different, but better.

[sebvi]

Dear @SibylleK , I will see what I can do, @rdosinski is on annual leave until February

[sebvi]

In the meantime I have updated the proposal with the suggestion from #284 (comment) and the branch as well