1. The IPWG and its relationship to WMO and CGMS
Dr Donald E. Hinsman
World Meteorological Organization
and
Dr James F.W. Purdom
CIRA, Colorado State University
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International Precipitation Working Group, Madrid, Spain, September 2002

2. Overview Locarno, Switzerland, June 1999
Melbourne, Australia, October 1999
CGMS-XXVIII, Woods Hole, USA, October 2000
Organizational IPWG Meeting, June 2001
CGMS XXIX, Isle of Capri, Italy, October 2001
Expanded space-based component of the GOS
WMO Space Programme
As the International Precipitation Working Group (IPWG) commences a most historic event ‑ its first session - it is appropriate to recall the developments that led to its formation. In recalling its genesis, IPWG will be better prepared to voyage into the future and serve the various communities that depend greatly not only on the forum provided by the sessions, but also the influence that IPWG can have on future developmental and operational activities aimed at more informed knowledge of precipitation processes and events as well as the ability to monitor them.
There have been several important milestones in the formation of IPWG. Prior to the first milestone, was the formation of two focused science working groups, the International TOVS (TIROS Operational Vertical Sounder) Working Group (ITWG) and the International Winds Workshops. These two groups highlighted the value in focused groups. WMO recognized the value of such groups as well as the need to foster similar activities in other areas. As a matter of priority, WMO felt it appropriate to foster a group in the area of precipitation estimation based on remotely sensed data.
A meeting of a CBS Open Programme Area Group on Integrated Observing Systems (OPAG IOS) Expert Team to Improve Satellite System Utilization, held at Locarno, Switzerland in 1999, was the first milestone in IPWG’s formation. Subsequent meetings of the Expert Team, WMO’s Executive Council and its Panel on Education and Training, the Commission for Basic Systems and the Coordination Group on Meteorological Satellites (CGMS) have all contributed to the present terms of reference, goals and sponsorship of IPWG. It is important to review these steps.
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International Precipitation Working Group, Madrid, Spain, September 2002

3. Locarno, Switzerland, June 1999
Discussed ways to leverage the science communities to improve the utilization of satellite data
Noted great success of ITWG and IWW
Suggested development of science teams and workshops to deal with other application areas of satellite meteorology
- NWP
- quantitative precipitation estimates
- ocean and land surface properties.
The Locarno meeting discussed a concept that had the potential to provide the capability to leverage the science communities and emerging communications technologies to improve the utilization of satellite data. In noting the great success of the International TOVS Working Group (ITWG) and the CGMS Winds Workshops in focusing the science communities on a specific application area's issues and problems, the meeting suggested the development of science teams and workshops that would deal with the application areas of satellite meteorology in NWP, quantitative precipitation estimates and ocean and land surface properties.
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International Precipitation Working Group, Madrid, Spain, September 2002

4. Melbourne, Australia, October 1999
Reviewed ITWG and IWW
Two Co-Chairs
Well supported
Meet every months
Strongly suggested WMO act as a catalyst in the development of such focused science groups
The Melbourne meeting responded to the suggestion made in Locarno. It reviewed the background and activities of two successful science groups, the International TOVS (TIROS Operational Vertical Sounder) Working Group (ITWG) and the CGMS (Coordination Group for Meteorological Satellites) International Winds Workshops (IWW).
The International TOVS Working Group (ITWG) was convened as a sub‑group of the International Radiation Commission (IRC) of the International Association of Meteorology and Atmospheric Physics (IAMAP). The ITWG has organized International TOVS Study Conferences (ITSCs) which have met every 18‑24 months since 1983.
Two Co-Chairs elected by the ITWG administered the ITWG. The Co-Chairs organized the ITCS and activities between conferences. The ITSC was well supported; e.g., ITSC-X was sponsored by NASA, NESDIS, EUMETSAT, the World Meteorological Organization, the Australian Bureau of Meteorology, Météo-France and ITT Industries.
The International Winds Workshop (IWW) had its genesis within the Co-ordination Group for Meteorological Satellites (CGMS) and had been convened every two years since Through these fora, data providers and operational and research users of the data shared information on the characteristics of satellite tracked winds to optimize their use, for example in NWP. Space Agencies provided status reports at IWWs. IWW working groups have reported on items such as methods, data utilization and verification. They also prepared recommendations to guide the directions of future research and to influence relevant programmes of WMO and other agencies.
Two Co-Chairs also administered the IWWs. They organized the IWWs as well as activities between conferences. IWW-VI was sponsored by NOAA, EUMETSAT, JMA and the World Meteorological Organization..
The Melbourne meeting thus suggested that the OPAG IOS Chairman inform the Commission for Basic Systems (CBS) and its Advisory Working Group (AWG) and in other appropriate venues of the benefits of science teams and workshops to improve the utilization of data in satellite meteorology in such applications areas as NWP, quantitative precipitation estimates and ocean and land surface properties. It further strongly suggested that WMO, through the Chairman of OPAG IOS, act as a catalyst in the development of such focused science groups.
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International Precipitation Working Group, Madrid, Spain, September 2002

5. CGMS-XXVIII, Woods Hole, USA, October 2000
CGMS-XXVIII was informed that the fifty-second session of the WMO Executive Council, held in June 2000, had recommended involving relevant science groups in a systematic manner and the positive indication from the GPCP for WCRP’s GEWEX to serve as a nucleus for such a working group. Thus, WMO strongly encouraged CGMS to participate in the formation of an International Precipitation Working Group with active participation by WMO and GPCP within the framework of CGMS.
Fifty-second WMO Executive Council (2000) recommended involving relevant science groups
Noted positive indication from the GPCP for WCRP’s GEWEX to serve as a nucleus for such a working group
WMO strongly encouraged CGMS XXVIII to form IPWG
- active participation by WMO and GPCP
- within the framework of CGMS
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International Precipitation Working Group, Madrid, Spain, September 2002

6. Organizational IPWG Meeting, June 2001
An organizational session of the Coordination Group for Meteorological Satellites (CGMS) and WMO sponsored International Precipitation Working Group was held at the CSU Tamasag Conference Facility, Fort Collins, Colorado, USA, June 2001.
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International Precipitation Working Group, Madrid, Spain, September 2002

7. Organizational IPWG Meeting, June 2001
Reviewed current status of precipitation estimation from satellite-based observing systems
Plans and capabilities of proposed future satellite systems
Discussed importance of WMO VL for E&T in Satellite Meteorology
The organizational session reviewed the current status of precipitation estimation from satellite-based observing systems and the plans and capabilities of proposed future satellite systems. Additionally, the organizational session discussed the importance of the WMO Virtual Laboratory for Education and Training in Satellite Meteorology and the relevance of the IPWG towards helping it achieve its goals.
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International Precipitation Working Group, Madrid, Spain, September 2002

8. Organizational IPWG Meeting, June 2001
Issues to be considered by IPWG
validation and independent verification of precipitation estimates
importance of the full implementation GSN
importance of water vapour and cloud micro-physics for next generation satellite rainfall estimation techniques;
relevance field experiments within the WWRP
relevance of satellite missions including GPM
importance of international cooperation
importance for IPWG to cover the needs of various communities including hydrometeorology, weather and climate
Issues to be considered in the formation of the IPWG:
validation and independent verification of precipitation estimates in the context of the scale of observation and the type of precipitation phenomena being characterized;
the importance of the full implementation of the GCOS Surface Network (GSN) to help in the validation effort;
the importance of water vapour and cloud micro-physics for the development of the next generation of satellite rainfall estimation techniques;
the relevance of planned field experiments within the World Weather Research Programme especially for warm season precipitation events and the assimilation of precipitation observations in forecast models;
the relevance of missions including the Global Precipitation Measurement (GPM) mission that would tie together active and passive instruments on polar-orbiting satellites with the high temporal observing capabilities afforded by geostationary satellites;
the importance of international cooperation in the areas of missions, validation, algorithms, new techniques, and education and training;
the importance of the IPWG covering the needs of various communities including hydrometeorology, weather and climate.
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International Precipitation Working Group, Madrid, Spain, September 2002

9. Organizational IPWG Meeting, June 2001
Developed IPWG terms of reference for approval by CGMS-XXIX
Agreed IPWG should be served by two Co-Chairmen and a Rapporteur to CGMS
Co-Chairmen
Dr Arnold Gruber
Dr Vincenzo Levizzani
Rapporteur
Dr James Purdom (Chair WMO OPAG IOS)
The organizational session reviewed the draft terms of reference for an International Precipitation Working Group. The session was guided by the terms of reference for the ITWG and CGMS Winds Working Group and the issues identified in its review of the current status of precipitation estimation from satellite-based observing systems.
The organizational session developed terms of reference for consideration and approval by CGMS-XXIX.
The organizational session agreed that the IPWG will be served by two Co-Chairmen and a Rapporteur to CGMS. The Co-Chairmen for IPWG are Dr Arnold Gruber (USA) and Dr Vincenzo Levizzani (Italy). It suggested that Dr Purdom (Chair WMO OPAG IOS) serve as the Rapporteur.
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International Precipitation Working Group, Madrid, Spain, September 2002

10. CGMS XXIX, Isle of Capri, Italy, October 2001
CGMS XXIX was informed of the organizational session held in Colorado in June It noted that terms of reference were drafted; they were guided by the terms of reference for the ITWG and CGMS Winds Working Group. CGMS reviewed the structure and terms of reference for the IPWG and approved them.
Noted Organizational session report
Noted terms of reference
Reviewed structure and terms of reference
Approved all
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International Precipitation Working Group, Madrid, Spain, September 2002

11. Expanded space-based component of the GOS
NASA confirmed its commitment to make observations available without restriction (applies to all relevant missions including Aqua, Terra, NPP, TRMM, GPM and QuickSCAT)
NASA’s missions de facto part of the space-based component of the GOS
NASDA indicated present and future satellite missions including TRMM, AMSR-E onboard Aqua, ADEOS II and the GCOM series should be considered part of the new R&D constellation for the space-based component of the GOS
In response to recommendations from the WMO Consultative Meetings on High-Level Policy on Satellite Matters, the 53rd Executive Council agreed to expand the space-based component of the GOS to include appropriate R&D satellites. R&D space agencies were informed and have formally responded as shown.
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International Precipitation Working Group, Madrid, Spain, September 2002

12. Expanded space-based component of the GOS
ESA has established a dialogue towards the availability of specific data and products from ESA’s ENVISAT mission
ESA intends to jointly organise a dedicated, specific AO to foster the use of data
Rosaviakosmos confirmed that experimental and R&D instruments on board its operational METEOR 3M N1 satellite as well as on its future Ocean series and other missions could be considered as a potential contribution to the space-based component of the GOS
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International Precipitation Working Group, Madrid, Spain, September 2002

13. WWW’s space-based component of the GOS (2002)
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International Precipitation Working Group, Madrid, Spain, September 2002

14. WMO Space Programme
Expanded space-based component of the GOS requires enhanced coordination
Guiding principles: optimization of the space-based system and the use of existing WMO structures fundamental
Inclusion of R&D satellite systems more than doubles the need for external coordination mechanisms
- Unique coordination needs between WMO and R&D space agencies
- Coordination between operational and R&D space agencies in such areas as frequency coordination, orbit coordination including equator crossing- times, standardization of data formats, standardization of user stations
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International Precipitation Working Group, Madrid, Spain, September 2002

15. WMO Space Programme (continued)
WMO has proposed an expansion of the present mechanisms for coordination
- increased cooperation between WMO and the operators of operational and R&D satellites, and
- within the WMO structure
Expand CGMS to include R&D space agencies contributing to the space-based component of the GOS
Relevant R&D agencies invited to CGMS XXX, November 2002
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International Precipitation Working Group, Madrid, Spain, September 2002

16. WMO Space Programme (continued)
CGMS - an important mechanisms to coordinate relevant matters
CGMS - principal forum for the necessary dialogue
- between WMO and satellite operators
- as well as for discussions between satellite operators
CGMS discussions - technical matters concerning data formats, work station configuration, commonality of satellite instruments and missions, coherent and coordinated mission planning, data dissemination systems, etc.
WMO's role - to state the observational and system requirements for WMO and supported programmes (GOS, GAW, GCOS, WCRP and WHYCOS)
CGMS satellite operators - make their voluntary commitments to meet the stated observational and system requirements
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International Precipitation Working Group, Madrid, Spain, September 2002

17. WMO Space Programme (continued)
WMO also agreed present WMO Satellite Activities programme insufficient to respond to new demands resulting from the expansion of the space-based component of the GOS to include the R&D constellation
WMO agreed to establish a WMO Space Programme as a matter of priority
Scope, goals and objectives respond to the tremendous growth in the utilization of environmental satellite data, product and services within the expanded space-based component of the GOS
- Regional workshops to make WMO Members aware of new capabilities
- Education and training events for R&D satellite data and products
- Workshops to identify selected instruments for transition from R&D to operational
Consultative Meetings on High-Level Policy on Satellite Matters to be institutionalized to more formally establish the dialogue and participation of environmental satellite agencies in WMO matters
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International Precipitation Working Group, Madrid, Spain, September 2002

18. Exciting times for WMO Members
Space-based component of the GOS greatly expanded
Provides valuable satellite data, products and services more so than ever before in the history of the World Weather Watch
WMO forward looking in establishing a new WMO Space Programme
- provides for both external and internal coordination necessary to maximize the exploitation of the new GOS
11/17/2018
International Precipitation Working Group, Madrid, Spain, September 2002