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W O R L D M E T E O R O L O G I C A L O R G A N I Z A T I O N

COMMISSION FOR INSTRUMENTS AND METHODS OF OBSERVATION

WORKING GROUP
on
GROUND-BASED UPPER-AIR OBSERVING SYSTEMS

New Delhi, India
6 - 10 December 1999

FINAL REPORT

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AGENDA

  1. ORGANISATION OF THE MEETING
  2. Opening of the meeting
  3. Working arrangements
  4. Adoption of the agenda
  5. INTRODUCTION
  6. Progress report of the chairman
  7. Working procedures for the intersessional period
  8. Evaluation of working progress
  9. Participation of manufacturers at meetings
  10. National progress reports
  11. Y2K status
  12. MATTERS RELATED TO RADIOSONDE OPERATIONS
  13. Report of the Rapporteur on Radiosonde Compatibility Monitoring
  14. Quality assurance of the radiosonde observing system
  15. Quality assurance during the production
  16. Laboratory evaluations and calibrations
  17. Training of operators
  18. Pre-flight quality checks
  19. Results from national / bilateral comparisons
  20. Review of data quality, including relative humidity measurements
  21. Status of GPS windfinding systems
  22. Coding issues including the input of surface observations and a plan for moving from TEMP code to BUFR
  23. Testing output from algorithms using standard data sets
  24. Review of automatic radiosonde launch systems
  25. Recommendations from the Expert Meeting on Operational Issues for Radiosonde Applications in the Tropics and Sub-tropics
  26. Priorities for future radiosonde developments
  27. MATTERS RELATED TO GROUND-BASED REMOTE SENSING SYSTEMS, INCLUDING REPORTS OF THE RELATED RAPPORTEURS
  28. MATTERS RELATED TO THE COMPATIBILITY OF GROUND-BASED OBSERVATIONS WITH OTHER OBSERVING SYSTEMS, INCLUDING REPORTS OF THE RELATED RAPPORTEURS
  29. RADIO-FREQUENCY ALLOCATIONS FOR GROUND-BASED OBSERVING SYSTEMS
  30. PREPARATION OF WORK PLANS AND TARGETS
  31. ANY OTHER BUSINESS
  32. CLOSURE OF MEETING

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GENERAL SUMMARY OF THE WORK OF THE SESSION
  1. ORGANIZATION OF THE SESSION
  2. Opening of the session

The session of the Working Group on Ground-based Upper-air Observing Systems (further called Working Group) was held at the Hotel Samrat in New Delhi, India, from 6 to 10December 1999 on kind invitation of the India Meteorological Department (IMD). The lists of participants and their addresses are attached as AppendicesA and B to this report.

The meeting was opened on Monday, 6 December 1999 at 10.00 a.m. by Dr R.R. Kelkar, Director-General of Meteorology of IMD and Permanent Representative of India with WMO. He welcomed the participants and noted IMD’s pleasure in hosting the session. He referred to the importance of considerations and exchange of experience in the field of upper-air in-situ and remote measurements and briefly informed on the work done by India in both areas. Dr Kelkar underlined that the conventional radiosonde measurements will remain, for many years to come, the backbone of the upper-air observation network. In this regard, he draw attention to the extended network of upper-air stations operated by IMD and to the fact that approximately 30,000 radiosondes were manufactured per annum within an IMD owned factory established for this purpose. He reiterated the importance of continued operation of radiosonde stations notwithstanding cost pressures although there were possible alternatives including profilers, Doppler radar, and satellite systems which might be considered as suitable means for replacement of in-situ observations in the future. He urged the Working Group to seek solutions for overcoming some difficult problems in radiosonde operation in India, mainly related to improving the quality of observations. He offered any support and hospitality to participants and wished them every success within the session and a nice stay in New Delhi.

Dr S.K. Srivastava, President of CIMO and Additional Director-General of Meteorology within IMD, emphasised in his statement the need for a strong observing system and for high quality observations as a requirement for all applications. He underlined that homogeneity of data was a critical issue, which needed serious considerations of all concerned but especially of CIMO experts. He underlined that IMD had learned the importance of standardisation and calibration through own experience and will support all efforts in this regard. He urged participants to focus their efforts on solutions and recommendations in this regard and offered his total support in his position in IMD as well as President of CIMO.

Dr J. Nash (UK), Chairman of the Working Group, thanked Dr Kelkar personally and the IMD for hosting the meeting. He saw it as an opportunity to bolster collaboration between countries around the world and especially as a significant contribution to the Global Observing System GOS. He suggested that quality of work and operations was important for consideration at the session. He hoped that experts from India, who attend the session either as member of the WG or as observers, could discuss matters of their concern and interact with the Working Group. Dr Nash sought bridge building between many countries to work effectively as a group to develop systems for the future. He welcomed the representatives of manufacturers and saw their participation as valuable. Co-operation between National Meteorological Hydrological Services (NMHSs) and manufacturers was essential and processes need to be considered to develop and make that interaction effective. He underlined in this regard that data accuracy was important since for example study of long-term changes in climate research required highly accurate data. He expressed a general sentiment that constructive criticism was very important to help improve systems. He finally referred briefly to some interesting topics of the Agenda for consideration. He invited experts to express their personal views and inform on their countries’ requirements.

Mr K. Schulze welcomed as representative of the WMO Secretariat the participants in New Delhi and conveyed the best wishes and the gratitude from Professor G.O.P. Obasi, Secretary General of WMO, to the delegates. He expressed his gratitude to India for its invitation to organise the session. He appreciated the efforts of Members of WMO to enable experts to participate and also that of several manufacturers of upper-air equipment for attendance of their representatives. The main purpose of inviting the latter is that Members requirements needed to be communicated effectively to manufacturers through WMO bodies, such as this Working Group. CIMO was a good vehicle for example to promote this important interaction. Mr Schulze emphasised that work of CIMO was the basis for quality of observations - many programmes and data users relied critically on the data quality. He, however, expressed his concern that the number of instrument experts still available for this important work seemed to be decreasing and no matter what the future of CIMO might be the work on instruments and quality has to be continued by WMO through experts’ work. Finally, he underlined that the most important objective of this Working Group session was to precisely define its work programme based on the terms of reference given by CIMO-XII and to allocate the tasks for the next two years to the experts concerned in noting that CIMO will meet in 2002. He wished the session every success in its work.

1.2Adoption of the agenda

The Chairman briefly introduced the Provisional Agenda and invited the participants for providing comments. Dr Griersmith raised the issue of Y2K problem, which was not yet reflected within the Provisional Agenda, and it was agreed it would briefly be addressed under Agenda Item2.6. The session then adopted the Agenda as basis for its work with the understanding that it could be amended during the session, if necessary. The final agenda can be found in front of this report.

1.3Working arrangements for the session

The session determined its working hours and the participants were informed on the local arrangements necessary for carrying out the session. English was selected the working language for the session.

  1. INTRODUCTION
  2. Progress report of the chairman

The chairman underlined that this first session of the Working Group after already more than one year since the CIMO XII passed is of high importance for accomplishing the work. Dr Nash highlighted in his progress report on the work done so far especially issues of radio frequency allocation and his own work in that area: this could have a big potential impact on future operations of Services (e.g. on upper-air observations). He underlined that several Member countries have not yet fully recognised the real potential impact of it. Several radio frequency bands are threatened, such as the 400-406 MHz band where there was tremendous pressures for its application for mobile satellite services (MSS).

Dr Nash underlined that another area of relevance to the Working Group was the ongoing studies on the upper-air component of the GOS, which require close collaboration with CBS. There was a strong view that a CBS representative preferably from one of CBS’s Open Programme Area Groups (OPAG) should take part in the further activities of the Working Group. It was noted that Dr Griersmith, Bureau of Meteorology of Australia (BOM), agreed to communicate relevant matters to Mr A. Sharp (also BOM) who was involved in the work of CBS related to representing upper-air systems in the study related to the redesign of the GOS.

Finally to this agenda item, the chairman expressed his appreciation to members of the Working Group and especially to the rapporteurs for the valuable contributions already provided.

2.2Working procedures for the intersessional period

The chairman drew the attention to the fact that the establishment of effective communication mechanism for exchanging information between the chairman and members of the Working Group is the most important measure besides the allocation of tasks to experts for getting the comprehensive work done best. In this connection it has to be taken into account that no further session of the Working Group can be convened prior to CIMO-XIII due to serious financial constraints while latter is planned to be held in autumn 2002.

In referring to Document 9 (Draft Work Plan for the Working Group), Dr Nash outlined some of the key issues pertaining to the primary task, and underlined that by end of 2001 major information and work results must be prepared to meet the needs for submission of documents for CIMO-XIII. He specifically highlighted in this regard that one overall aim of the work was to get the quality of radiosonde or ground-based upper-air data improved globally to better meet the increased requirements of users. For achieving this objective best, new concerted efforts needed to be made.

In further considering how the Working Group could conduct its business within the intersessional period, the meeting was informed that the holding of expert meetings with limited participation might still be a possible and suitable means for tackling current problems. However, such a meeting could be organised only if budgetary savings could be made available in WMO and when a strong justification can be given. An example in this regard was the recently organised Expert Meeting on Radiosonde Applications in the Tropics held in Geneva. The meeting noted that there was a strong requirement for better interaction with manufacturers of radiosondes at a time when many new products were being introduced, and when many changes were taking place in ground systems and operational procedures. A meeting once every four or five year with the relevant WMO experts seemed an inadequate method of interaction.

Dr Nash indicated that a good collaboration of the members of the Working Group, which includes all rapporteurs, with the chairman on one hand as well as between the experts on the other hand, is an essential precondition for the success of the work. This includes the regular exchange of information, the submission of outlines for contributions, and of reports for further considerations and improvement. It was informed that the concise documents, which have to be prepared for submission to CIMO-XIII, could reflect the working results of the group in a very limited manner only due to the significant limitation in words permitted for these contributions[1]. Furthermore it was noted with concern that only CIMO members and potential delegates of CIMOXIII would have access to these documents which do not have any official status after the commission session, since their contents will not be reflected in its Final Report. In considering this, it was agreed that in addition to these CIMOXIII documents more comprehensive reports should be prepared, which would reflect valuable output of the work in greater detail. They should be related to specific fields of interest as requested within the terms of reference of the Working Group or related to actual issues of common concern. These reports could be published within WMO’s Instruments and Observing Methods Report series (IOM series) and should, in addition, be put on WMO’s Web Home Page for general access. Furthermore, it should be considered to also publish them after an editing process in an appropriate scientific journal, if their content is of more general interest. Related to this, the Working Group considered whether some of the documents prepared for the WG session might already be suitable for this purpose after a review, such as Document 16 prepared by Mr Mannoji on GPS derived precipitable water content. (See relevant decisions of the Working Group as reflected further down in this report.)

Mr Mannoji: Preparation of a IOM publication on GPS derived water vapour content M1

In this regard the WG also noted with interest that there were already several nationally prepared reports of common interest available which contain valuable information, such as on radiosonde comparisons carried out nationally. If, for various reasons, these reports cannot be published by WMO, it was proposed to create a Hyperlink from WMO’s Web page to such reports, which have to be put on the related national Web page for making them accessible to a wider public.

2.3Evaluation of working progress

Based on the currently available working results and objectives, consideration were made towards enhancing the effectiveness of the work of the Working Group in view of the capacities and capabilities of their individual members. In this regard, Dr Nash suggested a target of improving compatibility of radiosonde data and integration with other observing systems such as aircraft and remote sensing. Related to this, he mentioned his concern that there were problems in getting the final report completed for the last WG established at CIMOXI which was also chaired by him. because of a poor flow of information from WG members. This problem has to be avoided in the working mechanism used in the intersessional period between the Commission sessions.

2.4Participation of manufacturers at sessions

The Working Group highly appreciated that representatives of 7 manufacturers[2] of upper-air equipment attended the session during the first three days. The chairman invited reports and comments from these manufacturers.

  • Mr Hoerhammer (Vaisala, Finland) cited two key issues, namely there was a need to improve communication of manufacturing requirements and feedback was required especially on the operation of GPS radiosondes related to wind data. He was concerned that the manufacturers could obtain access to all TEMP reports from their systems. He underlined that the ECMWF quality monitoring system has potential to give data on performance of radiosondes. He further underlined that about 75-80% of TEMP reports is already available on the Web. He noted with appreciation the approach of the NWS of the USA, as reflected in Appendix F of Doc. 3.
  • Dr Kats (KOMET, Russian Federation) informed that KOMET was established on the basis of Central Aerological Observatory (CAO) in 1996 by Roshydromet mainly for producing radiosondes to be applied within the Russian upper-air network mainly equipped with modernised AVK ground stations. Specialists of KOMET still continued research activities in upper-air measurements, including calibration and testing, especially for humidity measurements.
  • Mr Curran (Sippican/VIZ, USA) raised several issues. User requirements were often defined by each client, and so varied to an unnecessary extent, which could lead to an increase in the cost of the product. He underscored that user behaviour was sometimes very problematic. He urged CIMO to continue defining uniform requirements for general application as far as needed. He underlined that feedback to manufacturers was important and the already established good relation with CIMO’s upper-air experts should be enhanced. In partly responding, MrBower drew attention to an ensuing discussion by suggesting that standard for contracts and warranty compliance conditions would help as already applied by some Services.
  • Mr Naaman (Metatron, Israel) highlighted the information contained in Document 6 on the actual performance of operational radiosonde stations in specifically noting that GPS radiosonde performance was not yet satisfactory. He underlined that more attention of Members should be directed to the application radiotheodolites as a viable alternative within some climatic regions[3].
  • Mr Parini (InterMet Systems, USA) said the minimum requirement for radiosonde systems should be articulated as part of a basic system requirement. If users’ requirements increase, the recommendations should be specified so that manufacturers meet those standards.
  • Mr Pepin (Geolink, France) informed that they had a new generation radiosonde system was available for testing.

Resulting from related discussion on standards and quality including the need expressed by representatives of manufacturers it was agreed that interface standards for various components should be better articulated.

At a specific short side meeting with the representatives of manufacturers[4] which was held on invitation of and chaired by the Dr Srivastava, President of CIMO, with attendance of Mr D.C. Schiessl, Director for Basic Systems within the WMO Secretariat, the outcomes of the collaboration between WMO and manufacturers was reviewed and proposals developed on how to proceed best in this regard. The concise report of this meeting was prepared separately and was made available to those concerned.

2.5National progress reports

All members of the Working Group provided reports on issues related to the national upper-air-observing network more comprehensively reflected in the documents submitted to the session but concisely summarised below, as follows: