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QASUME Quality Assurance of Spectral Ultraviolet Measurements

The QASUME project aims to provide quality assurance for solar ultraviolet spectral irradiance measurements in Europe by comparing them with a traveling reference spectroradiometer. The project assesses the comparability of UV datasets in the European UV database and introduces an alternative to intercomparison campaigns.

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QASUME Quality Assurance of Spectral Ultraviolet Measurements

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  1. QASUMEQuality Assurance of Spectral Ultraviolet Measurements Project participants: Julian Gröbner PMOD/WRC A. Bais, S. Kazadzis, Aristotle University of Thessaloniki D. Rembges, Institute for Health & Consumer Protection, JRC-Ispra M. Blumthaler, J. Schreder, University of Innsbruck G. Seckmeyer, S. Wuttke, University of Hanover A. Webb, University of Manchester Institute of Science and Technolog P. Görtz, National Institute of Public Health and the Environment T. Koskela, Finnish Meteorological Institute Funded by the European Commission in the frame of the 5th framework programme (Contract: EVR1-CT2001-40011) 2002-2005 IPC-X

  2. Main objective: To explore a new method for providing QA to solar UV spectral irradiance measurements made in Europe, by comparison with a traveling reference spectroradiometer Specific goals: To introduce an alternative to intercomparison campaigns To assess the comparability of the UV datasets in the European UV database (EUVDB) Objectives of QASUME IPC-X

  3. What is solar Ultraviolet radiation ? Total ~ 1000 W/m2 UV ~ 53 W/m2 ( 5%) UVB ~ 1 W (0.1%) Definition: UVC = 100 - 280 nm UVB = 280 - 315 nm UVA = 315 - 400 nm IPC-X

  4. The Traveling Unit • Portable UV spectroradiometer • Bentham DM 150 double monochromator • Shaped Teflon diffuser with 6 m optical fiber • Temperature stabilization to ±0.5°C • Wavelength range 280 to 500 nm in steps of 0.25 nm • Spectral resolution 0.83 nm FWHM IPC-X

  5. The Traveling Unit • Portable calibrator • Six interchangeable 200 W Tungsten-Halogen Lamps • Lamps are traceable to PTB standards • Shaped to minimize reflections and allow natural cooling IPC-X

  6. JRC Jokioinen, Finland Validation of the QASUME traveling Unit Repeated visits to the same sites Bilthoven, the Netherlands Long term stability! IPC-X

  7. JRC Jokioinen, Finland Validation of the QASUME Traveling Unit Bilthoven, the Netherlands Diurnal Stability! IPC-X

  8. Direct traceability of the portable QASUME irradiance scale to the primary standard of the PTB Blackbody BB3200pg 2.5% 3% Gröbner J., and P. Sperfeld, Direct traceability of the portable QASUME irradiance scale to the primary irradiance standard of the PTB, Metrologia, 42, 134-139, 2005. IPC-X

  9. Expanded uncertainty approx. 5% The Traveling reference spectroradiometer Uncertainty budget Gröbner, J., et al., A travelling reference spectroradiometer for routine quality assurance of spectral solar ultraviolet irradiance measurements, Applied Optics,44, 5321-5331, 2005 IPC-X

  10. QA 2002-2004 Lampendusa IPC-X

  11. “not so good…” “good” Results for the QA-visits2002-2004 IPC-X

  12. And some more… • • • IPC-X

  13. Site No. of spectra /No. of days Ratio to B5503UVB / UVA-Vis. Variability in %5-95th percentile Austria, Innsbruck 53 / 3 1.00 / 0.98 4 Austria, Wien 45 / 4 1.08 / 1.04 8 Belgium, Brussels, 1 51 / 3 1.05 / 1.03 5 Belgium, Brussels, 2 52 / 3 0.97 / 0.96 9 Belgium, Brussels, 3 52 / 3 0.95 / 0.94 7 Czech, Hradec Kralove 52 / 3 0.98 / 0.97 5 EU - JRC, Ispra 1094 / 54 1.01 / 0.99 4 Finland, Jokioinen 228 / 8 1.03 / 1.02 6 Finland, Sodankyl 67 / 3 1.05 / 1.03 4 France, Briancon 65 / 3 0.90 / 0.87 5 France, Lille 55 / 3 1.01 / 0.99 8 Germany, Hanover 13 / 3 0.96 / 0.96 8 Germany, Lindenberg 41 / 2 0.98 / 0.96 6 Germany, Neuherberg 59 / 5 1.05 / 1.01 10 Great Britain, Manchester 64 / 4 1.28 / 1.27 14 Great Britain, Reading 79 / 4 0.99 / 0.98 8 Greece, Thessaloniki 116 / 8 1.04 / 1.03 8 Italy, Lampedusa 59 / 4 1.05 / 1.04 8 Italy, Rome 53 / 3 0.98 / 0.95 5 Netherlands, Bilthoven 133 / 7 1.04 / 1.03 6 Norway, Oslo 82 / 4 0.96 / 0.95 4 Norway, Trondheim 75 / 4 0.98 / 0.99 9 Poland, Warsaw 69 / 4 0.99 / 0.97 8 Portugal, Lisbon 86 / 4 1.21 / 1.16 11 Spain, El Arenosillo 95 / 5 0.95 / 0.89 8 Sweden, Norrköping 107 / 5 1.03 / 1.03 10 Results for the QA-visits2002-2004 Mean=1.01±0.07 N=29 N=29 IPC-X

  14. The traveling reference spectroradiometer (QASUME unit): Absolute uncertainty ~5% (8.8% at 300 nm and SZA 75°) Stability <1% (campaign duration) Diurnal variability 2% (2.8% at 300 nm) Absolute irradiance scale is representative of the European average. Quality Assurance at 25 UV monitoring sites in Europe: Most sites are within 10% of the QASUME unit. Most notable diurnal feature is due to angular response different from nominal (cosine). Cosine correction methods are not perfect! Homogenisation of the European UV monitoring sites is a long-term goal and Repeated visits to the same site are essential for this purpose. Since 2005 PMOD/WRC is hosting and operating the QASUME unit through a collaboration with JRC-Ispra who developed the instrument. Summary • Contact person for the QASUME unit: Julian Gröbner • (julian.groebner@pmodwrc.ch) IPC-X

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