The World Radiometric Reference and its Quality System ISO/IEC 17025

1. Wolfgang Finsterle, Isabelle Rüedi, and Silvio Koller The World Radiometric Reference and its Quality SystemISO/IEC 17025 Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 1

2. World Radiation Center The World Radiation Center (WRC) is operated by the Physikalisch-Meteorologisches Observatorium Davos (PMOD) on assignement by WMO. The WRC is financed by the Swiss governement. Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 2

3. WMO Mandate to WRC • To maintain the World Standard Group (WSG) for the realization of the World Radiometric Reference (WRR)Note: The WRR has been defined in 1980 based on the mean value of 15 absolutely characterized cavity radiometers. The WRR is the primary standard for solar irradiance. Today the WRR is realized by the WSG, a group of currently six reference pyrheliometers permanently installed at PMOD/WRC. • To ensure at all times the highest possible quality of its standards and testing equipment • To serve as calibration center for regional radiation centers worldwide Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 3

4. Calibration Tasks Calibration of: • Pyrheliometers • Pyranometers with the Sun as source Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook World Standard Group WSG candidates TECO2005 WRC/PMOD Quality Management 4

5. IPC - International Pyrheliometer Comparison • This key event is held every 5 years since 1959 • The goals are:- to ensure the homogeneityof solar irradiance measurements worldwide - to monitor WRR stability Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook IPC-IX 2000 • Participating instruments are comparedto the mean value of WSG instruments • validation of WRR stability based on IPC results TECO2005 WRC/PMOD Quality Management 5

6. WMO, BIPM, and the WRR • WMO and the Bureau International des Poids et Mesures (BIPM) co-operate to ensure that meteorological data are traceable to SI units • The quantity ‘Solar Irradiance’ was proposed to the Consultative Committee on Photometry and Radiometry (CCPR) • The ‘connection’ between the WRR (W/m2) and SI units needs to be validated Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 6

7. The Need for a Quality System • The WRR was originally defined in 1980 as the average of 15 absolutely characterized cavity radiometers • Since then it has served the meteorologial community as the primary standard for solar irradiance • Several ISO standards now require traceability to the WRR • The WRR is no longer only a meteorological standard but accepted in a much wider metrological community Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 7

8. To maintain the WSG and thus the WRR with the highest possible stability and to provide the highest possible world-wide homogeneity for solar irradiance measurements. Why ISO/IEC 17025? International recognition in the formal framework of the CIPM Mutual Recognition Arrangement (MRA) requires a Quality System (QS) according to the international standard ISO/IEC 17025. Conformance with ISO/IEC 17025 is also more and more requested by calibration customers. The QS at PMOD/WRC was introduced in December 2004 and presented to EUROMET QS-Forum 12 in February 2005. Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook Major goal of the quality system: TECO2005 WRC/PMOD Quality Management 8

9. PMOD / WRC Quality Management Quality Manger Department WORCC Not yet integrated Department Absolute and Shortwave Radiometry Head of Department Department Infrared Radiometry Not yet integrated QS Organization At this time the Quality System at PMOD/WRC covers only the department of ‘Absolute and Shortwave Radiometry’. It is planned to be extended in the future to cover all departments at PMOD/WRC. Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 9

10. Quality Manager • Top level QS tasks • Improvement and adaptation of the quality management handbook and associated documentation Head of Department • Transfer and implementation of top level QS into department • Full responsibility for department specific QS issues • WSG and data evaluation Laboratory Assistant • Execution and records of calibration tasks QS Responsibilities Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 10

11. Management Requirements ISO/IEC 17025 requires standard procedures, mechanisms, and plans to be followed for Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities Management Reqirements Technical Requirements Comparison WRR/SI Outlook Document Control Contracts Changes / Complaints / Non-conformities Audits / Management Reviews • The goal was to introduce already used, well-established processes into QS and to adapt them only where necessary • 1 and 2 were basically existing, 3 and 4 had to be defined and implemented • Short experience time=> usefulness and user friendliness still have to be proven TECO2005 WRC/PMOD Quality Management 11

12. QS Technical Requirements Calibration / Validation • Data evaluation procedures and timing definitions for every instrument type need to be documented • Pyrheliometers: based on ISO 9059 • Pyranometers: based on ISO 9846 • Differences to standards are stated in QS documentation • Techniques: • Use of reference standards (voltmeters) • Indirect comparison WSG <> cryogenic radiometer • Assessment of uncertainties Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 12

13. Environmental Conditions • Clear sky • Continuous weather watch during the calibration • Standard room temperature at data acquisition unit • Prohibited use of cell phones near DAQ hardware QS Technical Requirements Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook ISO/IEC 17025 requires Traceability to SI units, but: • WRR is a primaryreference • WRR is the onlyprimary reference for solar irradiance in the world (no key comparisons possible) • To-date cryogen radiometers cannot measure solar irradiance only indirect power comparisonsare possible • Power comparisons to national cryogen standards • Reference voltmeter calibration at certified laboratory TECO2005 WRC/PMOD Quality Management 13

14. QS Technical Requirements ISO/IEC 17025 requires detailed estimates of the uncertainties Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook • Individual estimates of uncertainties for each WSG member instrument werecalculated • Original estimate of absolute uncertainty for the WRR relative to SIunits is +/- 0.3% • Relative uncertainty WRR transfer < 300 ppm(Confirmed by IPC 1985 – 2000 results) • Individual estimates of uncertainties for different calibration items (instrument types) were calculated TECO2005 WRC/PMOD Quality Management 14

15. Comparison WRR/SI Results from recent intercomparisons between the WRR and cryogenic standards at METAS (Bern) and NPL (London) Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook NPL metas by Sandra Moebus TECO2005 WRC/PMOD Quality Management 15

16. Outlook • Implement requests from EUROMET QS-Forum 12 • 1st review of PMOD/WRC QS • Challenging tasks: • Enlargement of parallel data acquisition capability (2-3 years) • DAQ S/W development forIPC 2010 • Integration of the remaining two PMOD departments(Infrared and WORCC) Introduction PMOD/WRC Tasks IPC Metrology Quality System Organization Responsibilities ManagementReqirements Technical Requirements Comparison WRR/SI Outlook TECO2005 WRC/PMOD Quality Management 16

17. Thank you! Any questions? pmodwrc.ch TECO2005 WRC/PMOD Quality Management 17