# Presentation: 075167

## Briefing on Results from Annual Meeting of
WMO Expert Team on Data Representation and Codes (ET/DR+C) 

Jeff Ator
WG/MC Chair
July 3, 2007

**WMO Expert Team on Data Representation and Codes (ET/DR+C)**** **
- Jeff Ator
- WG/MC Chair
- July 3, 2007

## Table of Contents

- Background
- Outcome of U.S. Proposals
- Other Decisions and Agreements
- Additional Information

## Background

- The ET/DR+C is the official WMO team which reviews and makes recommendations on all proposed changes to BUFR, CREX, GRIB and GRIB2.  It also provides guidance on the use of these code forms to the WMO community.
- I have served as the U.S. representative to the ET/DR+C since 2001.
- The ET/DR+C held its annual meeting at the EUMETSAT headquarters in Darmstadt, Germany from April 23–27 2007.

## Outcome from U.S. proposals

- New BUFR Table B/D descriptors for use in reporting SBUV/2 ozone data – *Approved for pre-operational use*
- New BUFR Table B/D descriptors for use in reporting GFA/G-AIRMET data – *Approved for validation*
- Standard FXY numbers reserved for our use
- ECMWF agreed to assist in validation; Canada and UKMO will try to assist as well
- New GRIB2 code table entries – *Approved for pre-operational use*
- Code Table 4.1 – product discipline 10, parameter category 191 (Miscellaneous), entry 0 (# of seconds prior to initial reference time)
- Code Table 3.2 (Shape of the Earth) – entry 8 (Earth model assumed spherical with radius 6371200 m, but the horizontal datum of the resulting latitude/longitude field is the WGS84 reference frame)

## Other Decisions and Agreements

- New IEEE operator in BUFR Table C
- As part of new edition 5 of BUFR to become valid for operational exchange in November 2009
- Important for atmospheric chemistry and other applications with extreme value ranges
- Majority of group was in favor, despite implications for BUFR design, migration and software maintenance
- Obsolete entries in BUFR Common Code Table C-2 (Radiosonde types) to be re-used for TEMP reporting
- Table is full, and not everyone is ready to migrate to BUFR or CREX
- Idea is to add 100 to the decoded value beyond a certain date, since only 2 digits can be reported within TEMP code form
- Majority of group was in favor as “best of all possible solutions”, despite implications for migration and modification of TEMP software

## Other Decisions and Agreements (cont’d)

- Change units of BUFR descriptor 0-13-044 (K index) from Kelvin to Celsius
- As “editorial correction”, rather than deprecate and create new descriptor
- Celsius is the correct unit for this index, which became a BUFR descriptor in November 2005 and is only used by EUMETSAT
- Finalization of BUFR/CREX templates for traditional alphanumeric code forms (e.g. TEMP, SYNOP, SHIP)
- As learning aids for the migration process
- Many in the group wanted to now make these templates mandatory for international exchange of such data, but U.S. opposed this because of prior national work using alternative templates (e.g. RRS)
- Conversion of national data to international templates (by NWSTG/TOC) may be an option though

## Additional Information

- Upcoming changes to ICAO code forms including METAR, SPECI, TAF and SIGMET (effective November 7, 2007)
- No further changes were reported by ICAO this year, so see pages 90-102 of the report from last year’s ET/DR+C meeting: _[http://www.wmo.int/web/www/ISS/Reports/CodesMatters/REPORTCodesMontreal.doc](http://www.wmo.int/web/www/ISS/Reports/CodesMatters/REPORTCodesMontreal.doc)_
- In practice, many countries will not implement the changes but will instead file differences with ICAO
- The full report from this year’s ET/DR+C meeting is available at _[http://www.wmo.int/pages/prog/www/ISS/Reports/ET-DRC_EUMETSAT2007.doc](http://www.wmo.int/pages/prog/www/ISS/Reports/ET-DRC_EUMETSAT2007.doc)_