ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-4865-2008 Intercomparison of erythemal broadband radiometers calibrated by seven UV calibration facilities in Europe and the USA Hülsen G. 1 Gröbner J. 1 Bais A. 2 Blumthaler M. 3 Disterhoft P. 4 Johnsen B. 5 Lantz K. O. 4 Meleti C. 2 Schreder J. 6 Vilaplana Guerrero J. M. 7 Ylianttila L. 8 Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center, Dorfstrasse 30, 7278 Davos Dorf, Switzerland Aristotle University of Thessaloniki, Laboratory of Atmospheric Physics, Campus Box 149, 541 24 Thessaloniki, Greece Innsbruck Medical University, Division for Biomedical Physics, Müllerstr. 44, 6020 Innsbruck, Austria National Oceanic and Atmospheric Administration, Central UV Calibration Facility, 325 Broadway, 80305 Boulder, CO, USA Norwegian Radiation Protection Authority, Grini Naeringspark 13, 1361 Osteras, Norway CMS Ing. Dr. Schreder GmbH, Eggerstrasse 8, 6322 Kirchbichl, Austria Instituto Nacional de Técnica Aerospacial, Estación de Sondeos Atmosféricos El Arenosillo, 21130 Mazagon, Spain STUK, Radiation and Nuclear Safety Authority, Non-Ionizing Radiation Laboratory, P.O. Box 14, 00881 Helsinki, Finland 21 08 2008 8 16 4865 4875 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/8/4865/2008/acp-8-4865-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/4865/2008/acp-8-4865-2008.pdf

A bi-lateral intercomparison of erythemal broadband radiometers was performed between seven UV calibration facilities. The calibrations provided by the instruments owners were compared relative to the characterisation and calibration performed at PMOD/WRC in Davos, Switzerland. The calibration consisted in the determination of the spectral and angular response of the radiometer, followed by an absolute calibration performed outdoors relative to a spectroradiometer which provided the absolute reference. <br><br> The characterization of the detectors in the respective laboratories are in good agreement: The determinations of the angular responses have deviations below &plusmn;4% and the spectral responses agree within &plusmn;20%. A "blind" intercomparison of the erythemally weighted irradiances derived by the respective institutes and PMOD/WRC showed consistent measurements to within &plusmn;2% for the majority of institutes. One institute showed slightly larger deviation of 10%. The differences found between the different instrument calibrations are all within the combined uncertainty of the calibration.

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