Appendix D: Format and Contents of the GRH and IPR

Appendix D: Format and Contents of the GRH and IPR

D.1 Generic Record Header
    Field Description Type
    Size (bytes)
    Offset (bytes)
    RECORD_CLASS Class of Record enumerated
    1
    0
    INSTRUMENT_GROUP Defining group for record subclasses enumerated
    1
    1
    RECORD_SUBCLASS Subclass of this record class enumerated
    1
    2
    RECORD_SUBCLASS_VERSION Version of this particular format of the record case enumerated
    1
    3
    RECORD_SIZE Total size of the record case (including this header) u-integer4
    4
    4
    RECORD_START_TIME Start Time for this record - context will depend on record class short cds time
    6
    8
    RECORD_STOP_TIME Stop Time for this record - context will depend on record class short cds time
    6
    14
         
    Total
    20

D.1.1 RECORD_CLASS enumerated values

    Index
    		 Record Class Acronym
    0
    		 Reserved  
    1
    		 Main Product Header Record MPHR
    2
    		 Secondary Product Header Record SPHR
    3
    		 Internal Pointer Record IPR
    4
    		 Global External Auxiliary Data Record GEADR
    5
    		 Global Internal Auxiliary Data Record GIADR
    6
    		 Variable External Auxiliary Data Record VEADR
    7
    		 Variable Internal Auxiliary Data Record VIADR
    8
    		 Measurement Data Record MDR

D.1.2 INSTRUMENT_GROUP enumerated values

    Index
    		 Defining Group
    0
    		 GENERIC (no specific instrument)
    1
    		 AMSU-A
    2
    		 ASCAT
    3
    		 ATOVS instruments (AVHRR/3, HIRS/4, AMSU-A, MHS)
    4
    		 AVHRR/3
    5
    		 GOME
    6
    		 GRAS
    7
    		 HIRS/4
    8
    		 IASI (except IASI L2 products)
    9
    		 MHS
    10
    		 SEM
    11
    		 ADCS
    12
    		 SBUV
    13
    		 DUMMY
    14
    		 ARCHIVE (Note: Only used in GIADRs. A GIADR with INSTRUMENT_GROUP of archive contains only descriptive information and is not processed.)
    15
    		 IASI_L2 (used for IASI L2 products only)

D.1.3 RECORD_SUBCLASS values

This is determined by the Instrument Group and shall vary from instrument to instrument and also, if necessary, from processing level to processing level. The record subclasses are defined in the instrument-specific sections of this document.

D.1.4 RECORD_SUBCLASS_VERSION values

This is the version number of the record subclass. Any update to the format of the record subclass will result in the increment of the subclass version number.

D.1.5 RECORD_SIZE values

This field contains the total size of the record subclass (including the GRH) in bytes.

D.1.6 Definitions of RECORD_START_TIME and RECORD_STOP_TIME values

    Record Class Record Start Time Record Stop Time
    Main Product Header Record RECORD_START_TIME of the first MDR in the product RECORD_STOP_TIME of the last MDR in the product
    Secondary Product Header Record RECORD_START_TIME of the first MDR in the product RECORD_STOP_TIME of the last MDR in the product
    Internal Pointer Record RECORD_START_TIME of the first MDR in the product RECORD_STOP_TIME of the last MDR in the product
    Global External Auxiliary Data Record RECORD_START_TIME of the first MDR in the product RECORD_STOP_TIME of the last MDR in the product
    Global Internal Auxiliary Data Record RECORD_START_TIME of the first MDR in the product RECORD_STOP_TIME of the last MDR in the product
    Variable External Auxiliary Data Record The RECORD_START_TIME of the first MDR for which this data applies. The RECORD_STOP_TIME of the last MDR for which this data was applied.
    Variable Internal Auxiliary Data Record The RECORD_START_TIME of the first MDR for which this data applies. The RECORD_STOP_TIME of the last MDR for which this data was applied.
    Measurement Data Record Usually the "sensing time" of the first measurement in the record, but see individual PFSs for local definitions Usually the "sensing time" of the last measurement in the record, but see individual PFSs for local definitions

D.2 Generic Internal Pointer Record

    Field Description Type
    Size (bytes)
    Offset (bytes)
    TARGET_RECORD_CLASS Class of target record as derived from the GRH of the target record enumerated
    1
    0
    TARGET_INSTRUMENT_GROUP Defining group for target record subclass as derived from the GRH of the target record enumerated
    1
    1
    TARGET_RECORD_SUBCLASS Subclass of target record class as derived from the GRH of the target record enumerated
    1
    2
    TARGET_RECORD_OFFSET Offset of target record from start of product u-integer4
    4
    3
         
    Total
    7

The meaning of the TARGET_RECORD_CLASS, TARGET_INSTRUMENT_GROUP and TARGET_RECORD_SUBCLASS values correspond to those of the RECORD_CLASS, INSTRUMENT_GROUP and RECORD_SUBCLASS in the GRH above, respectively.

The TARGET_RECORD_OFFSET is given in bytes.