“Table-driven Code Forms (TDCF) are the solution to satisfy the demands of rapidly evolving science and technology, in view of their self-description, flexibility and expandability.”
(The Fourteenth WMO Congress (Cg-XIV), 2003)
The goal of the TDCF migration is the replacement of data exchange in Traditional Alphanumeric Codes (TAC) by Table-Driven Code Forms (TDCF). TDCF offers many advantages comparing to TAC such as: new data types, higher resolution and precision of data, metadata, flexibility and expandability. In near future all data in meteological network should be encoded in TDCF.
There are two codes for data encoding: BUFR and CREX.
BUFR – the Binary Universal Form for the Representation of meteorological data – is universal and portable binary format to store observation data and metadata, also offering packing of data.
CREX – Character form for the Representation and EXchange of data – is alphanumeric code that provides human readability, and is only a temporary step to BUFR and should be used where digital network is not available.
TDCF codes “are the ideal codes for observations and the best adapted to the fast scientific and technological evolution of the twenty-first century”. (Summary of the Plan for Migration to Table-Driven Code Forms (TDCF), WMO, 2002)
If you do not migrate...
Besides category 1 data migration which is
due this year, WMO plans to have all other
meteorological data being interchanged in
TDCF in the following years. Therefore without
reliable support of TDCF in your system you will
not be able to communicate with rest of the
meteorological world, to understand the data
received as well as to send data to others.
According to WMO Migration Plan, WMO members should:
Define a Migration Contact Point;
Establish a National Migration to TDCF Steering Group (MTSG);
Identify impacts of migration on national operation;
Produce a national migration plan;
Plan their requests for equipment and software (resources commitment);
Start a national training programme on TDCF;
As needed, modify or replace software used for observation, encoding, data concentration, dissemination systems, input data processing, message switching, decoding, visualisation and archiving;
Evaluate the implications, due to the migration process, on WMO Members' resources for development and operation;
Reserve the budget resources necessary to implement the migration.
BUFR migration tool is ready to help you with probably the most expensive and difficult step on your way to TDCF. It allows you to generate BUFR observations and data without an immediate upgrade of the observing hardware/software, support current legacy systems until they are upgraded or retired as scheduled.
The most direct way to migrate your data to TDCF is to produce TDCF data from measurement systems. Migration shall not affect operation of existing systems (both producing & processing) - however, there are practical issues in upgrading legacy systems for new codes, such as they might not be developed any longer, they cannot be ported for new compilers or operating systems, original developers are no longer available/reachable, or implement change is too expensive.
Solution is in bidirectional bridging of BUFR <—> TAC formats, which allows co-existence new and old systems. This will reduce need upgrade or change your systems immediately, as data currently generated in traditional forms will be automatically encoded with proper Metadata to BUFR. The other way round by providing old codes from BUFR prolongs usability of your current systems to allow proper development of new tools and migration when ready part-by-part.
It is important to note that plain Conversion is not a Migration. Because resulting data will miss additional precision and important metadata. Therefore TDCF Migration Tool provides more by Enriching BUFR with proper metadata or additional data, in order to provide real value and step forward.
For example with for SYNOPs additional metadata contain station coordinates, station name, elevation, height of each sensor above ground, type of sensors, etc. Since SYNOP (in FM-12 alphanumeric code) contains data in sufficient precision but it does not carry proper metadata, their are added in TDCF Migration Tool and during encoding in roder to produce fully rich & valid BUFR with Synoptic observation.