Binary Universal Form Representation (BUFR) Paul Hamer November, 2009 Self introduction: Oliver suggested presentation on BUFR WMO definition “Binary universal form for the representation of meteorological data“ Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 1 1

WMO Table Driven Code Forms Why BUFR is important? WMO 14th Congress in 2003 supported the adoption of TDCF’s. TDCF’s include BUFR/CREX and GRIB. Migration to BUFR to be complete by 2015. (CREX – Character form for Representation and EXchange.) Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 2 2

Global Systems Division (GSD) Earth System Research Laboratory (ESRL) WMO BUFR Documentation and standard code tables from WMO (http://www.wmo.ch/pages/prog/www/WMOCodes/OperationalCodes.html) Edition 4 in use from November 2005 but use of edition 3 use allowed  until 2012. (Note: A BUFR message shall not mix features of different editions; the content shall be consistent and in accordance with a single edition.) Version numbers correspond to code table versions. (Master table version is currently 14). Master table versions up to and including version 13 are a superset. A further discussion of tables will be included in metadata. Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 3 3

Global Systems Division (GSD) Earth System Research Laboratory (ESRL) WMO BUFR BUFR is the name of a binary code for the exchange and storage of data. (Note: Not just meteorological) The BUFR message consists of a continuous bit-stream made of a sequence of octets (1 octet = 8 bits).  The terms “BUFR message” and “section” describe logical entities to assist BUFR definition. A BUFR message consists of one or more subsets of related data defined, described and represented by a single BUFR entity. The octets of a BUFR message are grouped in sections. Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 4 4

Global Systems Division (GSD) Earth System Research Laboratory (ESRL) WMO BUFR Sections All WMO TDCF’s break messages into sections. For BUFR these are: Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 5 5

Data Description Section The data description section contains the “descriptors” of data contained in the data section. Each descriptor shall occupy 2 octets and contain 3 parts: F (2 bits), X (6 bits) and Y (8 bits). F = 0 is known as the element descriptor that refers to a single element in BUFR Table B. X denotes the Table B class and Y the entry with that class. F = 1 refers to replication, F = 2 denotes an operator descriptor and F = 3 denotes a sequence operator. Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 6 6

Global Systems Division (GSD) Earth System Research Laboratory (ESRL) BUFR Table B Example Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 7 7

WMO BUFR Issues/Solutions? Decoding requires access to appropriate tables. Publish tables in XML Make all tables available at all National Centers Format defines no standard way of encoding a given dataset. Use Templates, i.e. Define the encoding for certain datasets. Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 8 8

Global Systems Division (GSD) Earth System Research Laboratory (ESRL) WMO BUFR Questions? Global Systems Division (GSD) Earth System Research Laboratory (ESRL) 9 9