Section Name BUFR (see Manual on Remarks Number Codes (WMO-No. 306) 0 Indicator Starting with length of “BUFR”; section message, BUFR edition number 1 Identification A Data category Length of section, identification – section of the message. For use code figure 4, level “Single data (other than satellite)” 2 Optional Length of section and additional section items for local use by automatic data processing centres. Not required for AMDAR 3 Data Table B Classification of Length of section, number of data – description elements subsets, data category flag, data section compression flag and a Table C Data description – collection of descriptors which operators define the form and content of Table D List of common – individual data elements sequences 4 Data section B Classification of Length of section and binary – elements data C Data description – operators Table D List of common – sequences 5 End section Ending with “7777” Within the BUFR bulletin, the most relevant sections are section 1 (Identification section, containing metadata of the bullet itself), and sections 3 and 4 (Data description and Data section, respectively). Typically, section 3 presents the list of descriptors and common sequences for the datasets, reported in section 4. Descriptors Variables, code tables and other elements are represented by so-called descriptors. Schematically, a BUFR descriptor can be visualized as follows: F X Y 2 6 8 BITS BITS BITS F denotes the type of descriptor. With 2 bits, there are 4 possible values for F: 0, 1, 2 and 3. The four values have the following meanings: F = 0 - Element descriptor, and refers to Table B entries F = 1 - Replication operator F = 2 - Operator descriptor, and refers to Table C entries F = 3 - Sequence descriptor, and refers to D entries The meanings of and uses for X and Y depend on the value of F. Evidently, for variables and code tables most relevant are the values for F = 0 or 3. For these values, the descriptor refers to BUFR Tables B or D. X (6 bits) indicates the class or category of descriptor within the Table. In case F=0 reference is made to single variables or predefined table values. For instance, F-X-Y = 0-12-101 stands for temperature” (Class 12, “Temperature/air
Section Number Name BUFR (see Manual on Codes (WMO-No. 306) Remarks 0 Indicator section Starting with “BUFR”; length of message, BUFR edition number 1 Identification section A – Data category Length of section, identification of the message. For use code figure 4, “Single level data (other than satellite)” 2 Optional section Length of section and additional items for local use by automatic data processing centres. Not required for AMDAR 3 Data description section Table B – Classification of elements Table C – Data description operators Table D – List of common sequences Length of section, number of data subsets, data category flag, data compression flag and a collection of descriptors which define the form and content of individual data elements 4 Data section B – Classification of elements C – Data description operators Table D – List of common sequences Length of section and binary data 5 End section Ending with “7777” Within the BUFR bulletin, the most relevant sections are section 1 (Identification section, containing metadata of the bullet itself), and sections 3 and 4 (Data description and Data section, respectively). Typically, section 3 presents the list of descriptors and common sequences for the datasets, reported in section 4. Descriptors Variables, code tables and other elements are represented by so-called descriptors. Schematically, a BUFR descriptor can be visualized as follows: F X Y 2 BITS 6 BITS 8 BITS F denotes the type of descriptor. With 2 bits, there are 4 possible values for F: 0, 1, 2 and 3. The four values have the following meanings: F = 0 - Element descriptor, and refers to Table B entries F = 1 - Replication operator F = 2 - Operator descriptor, and refers to Table C entries F = 3 - Sequence descriptor, and refers to D entries The meanings of and uses for X and Y depend on the value of F. Evidently, for variables and code tables most relevant are the values for F = 0 or 3. For these values, the descriptor refers to BUFR Tables B or D. X (6 bits) indicates the class or category of descriptor within the Table. In case F=0 reference is made to single variables or predefined table values. For instance, F-X-Y = 0-12-101 stands for “Temperature/air temperature” (Class 12,
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