1. Report of the ET-UGRN Mr Rainer Dombrowsky
Commission for Instruments and Methods of Observation Fourteenth Session Geneva, 7 – 14 December 2006
Report of the ET-UGRN
Mr Rainer Dombrowsky

2. Summary of ET-UGRN Activities
Radiosonde Performance Reporting Activities
Questionnaire on Radiosonde Measurement Monitoring Techniques
Climate Requirements for UA
BUFR Templates for TEMP Code
Migration to Binary Codes
Survey on UA Operational Cost Reduction
Radiosonde Frequency Issues
1. In collaboration with the other UA ETs the issue of designation “higher quality radiosondes” was discussed the requirements for reference radiosondes and their associated problems which ranged from technical issues to issues of cost. These discussions led to encouragement from the GUAN for the ET to work closely with HMEI in developing reference quality radiosondes. These discussions led to a couple of workshops conducted bringing radiosonde data users and manufacturers together to discuss the full range of requirements on radiosondes and to examine the feasibility of using radiosondes to calibrate satellites. The initial meeting was held in Ashville, NC in 2003 and the follow-on workshop in These resulted in defining the requirements of the climate community and how the GUAN should evolve. Members of the ET-URGN and the ET-UASI participated in these workshops to discuss radiosonde performance and concerns over perceived shortcomings in the current measurement network. Since the last workshop GCOS has developed its Implementation Plan involving the establishment of a Global Climate Observing System Reference Upper-Air Network (GRUAN). The WMO representative recommended that this network use high quality reference radiosondes as identified from the Mauritius Intercomparison.
The ET addressed the issue of the development of techniques and annual reports on the performance of radiosonde types in the GOS. Mr Tim Oakley of the UK Met Office supported these global activities through preparation of annual reports on radiosonde measurements. In his capacity as Rapporteur on Radiosonde Capabilities Mr Oakley maintained an excellent relationship with CIMO members and HMEI, through his monitoring of radiosonde performance, reporting on issues and preparing annual summaries for posting on the CIMO website. During the intersessional period Mr Oakley also developed a December 2003 report to the Commission on Basic Services on the status of the radiosonde types used in the TEMP code. The CIMO MG acknowledges the outstanding efforts of Mr Oakley and thanks him for his exceptional efforts.
2. ET-UGRN members Mr D. Dockendorff (Environment Canada) and Mr Roger Atkinson (the Australian Bureau of Meteorology) developed a Questionnaire on Techniques used to Monitor Radiosonde Measurements. Due to a change in issuing questionnaires the questionnaire will be distributed early in All responses will be analyzed and results provided to members. The results will be used during the intersessional period in developing a plan for effective radiosonde data quality monitoring and performance measurement on a global basis.
3. The ET was requested to coordinate with HMEI and solicit an agreement on BUFR code tables and descriptors for International use. In this regard, Mr Oakley reviewed the current code table and identified those radiosonde descriptors that were obsolete. This was to allow new radiosonde designs to be added to the code table and this was completed shortly after the ET-UGRN initial session. It was expected that this code table would be used for the BUFR message and that later versions would be more detailed through the addition of metadata within the BUFR message. At the most recent joint meeting of the Coordination Team on Migration to Table Driven Code Forms and the Expert Team on Data Representation, Mr Fred Branski (as an invited expert to the ET-UGRN) reported that HMEI had agreed to the BUFR templates for TEMP code.
4. The ET was asked to investigate how CIMO would become involved in the strategy for migration toward use of binary codes. The ET noted that CBS had the responsibility for developing a migration strategy and CBS has developed a Migration Implementation Plan (MIP) providing guidance to WMO Members. The ET stated that CIMO review the MIP and be prepared to provide guidance to on CIMO related issues within the MIP. The ET has reviewed the inforamtion presented and has endorsed the need to migrate to BUFR as soon as feasible, but not later than the dates provided in the migration plan developed by CBS and endorsed by Congress.
5. The ET has continued to monitor the progress of AMDAR and how AMDAR measurements might be integrated into upper-air databases in the form of complimentary data. Congress and the Executive Council have directed CAeM and CBS to more fully integrate AMDAR into the WWW global observing system. The ET will work closely with the AMDAR Panel and the ET-USAI in determining the quality of AMDAR data and if found to be acceptable develop guidelines and establish operational performance standards for all meteorological elements reported by AMDAR.
6. Mr S. El-Fouly, Egyptian Meteorological Services, investigated measures for reducing the upper-air operational costs and conducted a survey to identify different options; 27 member states were involved in the survey but only a few responded. Despite the small sample return, Mr El-Fouly’s findings confirmed the need for more assistance to developing countries.
7. The issues concerning radiosonde frequencies were addressed by Mr David Franc who is a representative to the International Telecommunications Union. Mr Franc also is a member of the CBS Steering Group on Radio Frequency Coordination and he indicated that the steering group in collaboration with HMEI have defined objectives for developing spectrally efficient radiosonde transmitters and receivers. Mr Franc has represented the ET and CIMO at these meetings providing recommendations for protecting the various meteorological radio frequency bands. During the session several efforts were conducted to develop technical information for support of radio frequency sharing policy for WRC. Through input from members of the ET-UGRN, the CBS Steering Group on Radio Frequency Coordination (SG-RFC) contributed to the development of an International Telecommunications Union (ITU) recommendation that addresses the need for
spectrum sharing between radiosonde and meteorological satellites in the band MHz. Such issues will be revisited once again by the ITU in 2008.
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