GRIB2 - PRODUCT DEFINITION TEMPLATE 4.79

Individual ensemble forecast, control and perturbed, at a horizontal level or in a
horizontal layer in a continuous or non-continuous time
interval for atmospheric chemical constituents with source or sink

Created 03/01/2023


Octet No. Contents
10
 Parameter category (see Code table 4.1)
11
 Parameter number (see Code table 4.2)
12-13
 Atmospheric chemical constituent type (see Code table 4.230)
14
 Source or sink (see Code table 4.238)
15
 Type of generating process (see Code Code Table 4.3)
16
 Background generating process identifier (defined by originating centre)
17
 Forecast generating process identifier (defined by originating centre)
18-19
 Hours after reference time of data cut-off (see Note 1)
20
 Minutes after reference time of data cut-off
21
 Indicator of unit of time range (see Code table 4.4)
22-25
 Forecast time in units defined by octet 21 (see Note 2)
26
 Type of first fixed surface (see Code table 4.5)
27
 Scale factor of first fixed surface
28-31
 Scaled value of first fixed surface
32
 Type of second fixed surfaced (see Code table 4.5)
33
 Scale factor of second fixed surface
34-37
 Scaled value of second fixed surfaces
38
 Type of ensemble forecast (see Code table 4.6)
39
 Perturbation number
40
 Number of forecasts in ensemble
41-42
 Year of end of overall time interval
43
 Month of end of overall time interval
44
 Day of end of overall time interval
45
 Hour of end of overall time interval
46
 Minute of end of overall time interval
47
 Second of end of overall time interval
48
 n - number of time range specifications describing the time intervals used to calculate the statistically processed field
49-52
 Total number of data values missing in statistical process

53-64 Specification of the outermost (or only) time range over which statistical processing is done
53
 Statistical process used to calculate the processed field from the field at each time increment during the time range (see Code table 4.10)
54
 Type of time increment between successive fields used in the statistical processing (see Code table 4.11)
55
 Indicator of unit of time for time range over which statistical processing is done (see Code table 4.4)
56-59
 Length of the time range over which statistical processing is done, in units defined by the previous octet
60
 Indicator of unit of time for the increment between the successive fields used (see Code table 4.4)
61-64
 Time increment between successive fields, in units defined by the previous octet (see Notes 3 and 4)

65-nn These octets are included only if n > 1, where nn = 52 + 12 x n
65-76
 As octets 53 to 64, next innermost step of processing
77-nn
 Additional time range specifications, included in accordance with the value of n. Contents as octets 53 to 64, repeated as necessary


Notes:

1. Hours greater than 65534 will be coded as 65534

2. The reference time in section 1 and the forecast time together define the beginning of the overall time interval.

3. An increment of zero means that the statistical processing is the result of a continuous (or near-continuous) process, not the processing of a number of discrete samples. Examples of such continuous processes are the temperatures measured by analogue maximum and minimum thermometers or thermographs, and the rainfall measured by a rain gauge.

4. The reference and forecast times are successively set to their initial values plus or minus the increment, as define by the type of time increment (one of octets 54, 66, 78, …). For all but the innermost (last) time range, the next inner range is then processed using these reference and forecast times as the initial reference and forecast times.


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