ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-3369-2008 Quality assurance of the Brewer spectral UV measurements in Finland Lakkala K. 1 Arola A. 2 Heikkilä A. 2 Kaurola J. 2 Koskela T. 2 Kyrö E. 1 Lindfors A. 2 Meinander O. 2 Tanskanen A. 2 Gröbner J. 3 Hülsen G. 3 Finnish Meteorological Institute, Arctic Research Centre, Sodanlylä, Finland Finnish Meteorological Institute, Helsinki, Finland Physikalisches Meteorologisches Observatorium Davos, World Radiation Center, Davos Dorf, Switzerland 30 06 2008 8 13 3369 3383 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/8/3369/2008/acp-8-3369-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/3369/2008/acp-8-3369-2008.pdf

The quality assurance of the two Brewer spectrophotometers of the Finnish Meteorological Institute is discussed in this paper. The complete data processing chain from raw signal to high quality spectra is presented. The quality assurance includes daily maintenance, laboratory characterizations, calculation of long-term spectral responsivity, data processing and quality assessment. The cosine correction of the measurements is based on a new method, and is included in the data processing software. The results showed that the actual cosine correction factor of the two Finnish Brewers can vary between 1.08–1.13 and 1.08–1.12, respectively, depending on the sky radiance distribution and wavelength. The temperature characterization showed a linear temperature dependence between the instruments' internal temperature and the photon counts per cycle, and a temperature correction was used for correcting the measurements. The long-term spectral responsivity was calculated using the time series of several lamps using two slightly different methods. The long-term spectral responsivity was scaled to the irradiance scale of the Helsinki University of Technology (HUT) for the whole of the measurement time-periods 1990–2006 and 1995–2006 for Sodankylä and Jokioinen, respectively. Both Brewers have participated in many international spectroradiometer comparisons, and have shown good stability. The differences between the Brewers and the portable reference spectroradiometer QASUME have been within 5% during 2002–2007.

 References Aaltonen, V., Lihavainen, H., Kerminen, V.-M., Ginzburg, M., Kulmala, M., and Viisanen, Y.: Three years of AOD measurements at three bipolar sites, in: NOSA 2006 Aerosol symposium, combined with the X Finnish National Aerosol Symposium, Finnish-Czech Aerosol Symposium, and BACCI workshop, Helsinki 8.–10.11.2006, Report Series in Aerosol Science, 83, 17–20, 2006. Arola, A., Kaurola, J., Koskinen, L., Tanskanen, A., Tikkanen, T., Taalas, P., Herman, J., Krotkov, N., and Fioletov, V.: A new approach to estimate the albedo for snow-covered surface in space-borne retrieval method, J. Geophys. Res., 108, 4531, \doi10.1029/2003JD003492, 2003a. Arola, A., Lakkala, K., Bais, A., Kaurola, J., Meleti, C., and Taalas, P.: Factors affecting short- and long-term changes of spectral UV irradiance at two European stations, J. Geophys. Res., 108, 4549, \doi10.1029/2003JD003447, 2003b. \bibitem[Arola et~al.(2007)Arola, Lindfors, Natunen, Lehtinen] arola2007Arola, A., Lindfors, A., Natunen, A., and Lehtinen, K.: A case study on biomass burning aerosols: effects on aerosol optical properties and surface radiation levels, Atmos. Chem. Phys., 7, 4257–4266, 2007. Bais, A., Zerefos, C., and McElroy, C.: Solar UVB measurements with the double- and single-monochromator Brewer Ozone Spectrophotometers, Geophys. Res. Lett., 23, 833–836, 1996. Bais, A., Kazadzis, S., Balis, D., Zerefos, C., and Blumthaler, M.: Correcting global solar ultraviolet spectra recorded by a Brewer spectroradiometer for its angular response error, Appl. Optics, 37, 6339–6344, 1998. Bais, A., Gardiner, B., Slaper, H., Slaper, H., Blumthaler, M., Bernhard, G., McKenzie, R., Webb, A R., Seckmeyer, G., Kjeldstad, B., Koskela, T., Kirsch, P J., Gröbner, J., Kerr, J B., Kazadzis, S., Leszczynski, K., Wardle, D., Brogniez, C., Josefsson, W., Gillotay, D., Reinen, H., Weihs, P., Svenœ, T., Eriksen, P., Kuik, F., and Redondas, A.: The SUSPEN intercomparison of ultraviolet spectroradiometers, J. Geophys. Res., 106, 12 509–12 525, 2001. Bais, A., Blumthaler, M., Gröbner, J., Seckmeyer, G., Webb, A R., Görts, P., Koskela, T., Rembges, D., Kazadzis, S., Schreder, J., Cotton, P., Kelly, P., Kouremeti, N., Rikkonen, K., Studemund, H., Tax, R., and Wuttke, S.: Quality assurance of spectral ultraviolet measurements in Europe through the development of a transportable unit (QASUME), in: Ultraviolet Ground- and Space-Based Measurements, Models, and Effects II, edited by: Gao, W., Herman, J R., Shi, G., Shibasoki, K., and Slusser, J R., SPIE 4896, 232–238, 2003. Bais, A., Kazadzis, S., Garane, K., Kouremeti, N., Gröbner, J., Blumthaler, M., Seckmeyer, G., Webb, A., Koskela, T., Görts, P., and Schreder, J.: Portable device for characterizing the angular response of UV spectroradiometers, Appl. Optics, 44, 7136–7143, 2005. Bernhard, G. and Seckmeyer, G.: Uncertainty of measurements of spectral solar UV irradiance, J. Geophys. Res., 104, 14 321–14 345, 1999. Bernhard, G., Booth, C R., and Ehramjian, J C.: Version 2 data of the National Science Foundation Ultraviolet Radiation Monitoring Network: South Pole, J. Geophys. Res., 109, \doi10.1029/2004JD005584, 2004. Bernhard, G., Booth, C R., and Ehramjian, J C.: Real-time ultraviolet and column ozone from multichannel ultraviolet radiometers deployed in the National Science Foundations ultraviolet monitoring network, Opt. Eng., 44, 2005. Blumthaler, M.: Quality assurance and quality control methodologies used within the Austrian UV monitoring network, Radiation Protection Dosimetry, 111, 359–362, \doi10.1093/rpd/nch054, 2004. Booth, C., Lucas, T., and Morrow, J.: High resolution UV spectral irradiance monitoring program in polar regions: Five years (and growing) of data available to polar research in ozone- and ultraviolet -related studies, Antarct. J. U. S., pp. 338–341, 1992. Booth, C., Bernhard, G., Ehramjian, J., Quang, V., and Lynch, S.: NSF Polar Programs UV Spectroradiometer Network 1999–2000 Operations Report, Tech. rep., Biospherical Instruments Inc., San Diego, 219 pp., 2001. Cappellani, F. and Kochler, C.: Temperature effects correction in a Brewer MKIV spectrophotometer for solar UV measurements, J. Geophys. Res., 105, 4829–4831, 1999. De~Backer, H., Köpke, P., Bais, A., De~Cabo, X., Frej, T., Gillotay, D., Haite, C., Heikkilä, A., Kazantzidis, A., Koskela, T., Kyrö, E., Lapeta, B.and~Lorente, J., Masson, K., Mayer, B., Plets, H., Redondas, A., Renaud, A., Schauberger, G., Schmalwieser, A., and Vaniceck, K.: Comparison of measured and modelled UV indices for the assessment of health risks., Meteorol. Appl. 8, 267–277, 2001. Feister, U., Grewe, R., and Gericke, K.: A method for correction of cosine errors in measurements of spectral UV irradiance, Solar Energy, 60, 313–332, 1997. Garane, K., Bais, A., Kazadzis, S., Kazantzidis, A., and Meleti, C.: monitoring of UV spectral irradiance at Thessaloniki (1990-2005): data re-evaluation and quality control, Ann. Geophys., 24, 3215–3228, 2006. Gardiner, B G. and Kirsch, P J.: Intercomparison of ultraviolet spectroradiometers, Ispra, 24–25 May 1995, in: Advances in Solar Ultraviolet Spectroradiometry, Air Pollut. Res. Rep. 63, edited by: Webb, A R., 67–151, Eur. Commun., Luxembourg, 1997. Glandorf, M., Arola, A., Bais, A., and Seckmeyer, G.: Possibilities to detect trends in spectral UV irradiance, Theoretical and Applied Climatology, 81, 33–44, \doi10.1007/s00704-004-0109-9, 2005. Gröbner, J. and Sperfeld, P.: Direct traceability of the portable QASUME irradiance standard of the PTB, Meteorologia, 42, 134–139, 2005. Gröbner, J., Rembges, D., Bais, A F., Blumthaler, M., Cabot, T., Josefsson, W., Koskela, T., Thorseth, T M., Webb, A R., and Wester, U.: Quality Assurance of Reference Standards From Nine European Solar-Ultraviolet Monitoring Laboratories, Appl. Optics, 41, 4278–4282, 2002. Gröbner, J., J., S., Kazadzis, S., Bais, A F., Blumthaler, M., Görts, P., Tax, R., Koskela, T., Seckmeyer, G., Webb, A R., and Rembges, D.: Traveling reference spectroradiometer for routine quality assurance of spectral solar ultraviolet irradiance measurements, Appl. Optics, 44, 5321–5331, 2005. Huttunen, S., Taipale, T., Lappalainen, N M., Kubin, E., Lakkala, K., and Kaurola, J.: Environmental specimen bank samples of Pleurozium schreberi and Hylocomium splendens as indicators of the radiation environment at the surface, Environ. Pollut., 133, 315–326, 2005. Josefsson, W.: UV radiation 1983–2003 measured at Norrköping, Sweden, Theor. Appl. Climatol., 83, 59–76, \doi10.1007/s00704-005-0160-1, 2006. Kazantzidis, A., Bais, A F., Gröbner, J., Herman, J R., Kazadzis, S., Krotkov, N., Kyrö, E., den Outer, P N., Garane, K., Görts, P., Lakkala, K., Meleti, C., Slaper, H., Tax, R B., Turunen, T., and Zerefos, C S.: Comparison of satellite-derived UV irradiances with ground-based measurements at four European stations, J. Geophys. Res., 111, \doi10.1029/2005JD006672, 2006. Kjeldstad, B., Johnsen, B., and Koskela, T.: The Nordic Intercomparison of Ultraviolet and Total Ozone Instruments at Izaña, October 1996. Final Report., 36, Meteorologisia julkaisuja\/, Ilmatieteen laitos, Helsinki, 1997. Koskela, T.: The Nordic Intercomparison of ultraviolet and total ozone instruments at Izaña from 24 October to 5 November 1993. Final report, 27, Meteorologisia julkaisuja\/, Ilmatieteen laitos, Helsinki, 1994. Koskela, T.: On the stability of an irradiance calibration lamp, in: Extended Abstracts of the 2nd Workshop at PTB, Braunschweig 9–11 November 1998, the Thematic Network on UV Measurements, UVNEWS, Issue 2, ISSN 1456-2537, 30–31, http://metrology.hut.fi/uvnet/source/UVNEWS2.htm, 1999. Kübarsepp, T., Kärhä, P., Manoocheri, F., Nevas, S., Ylianttila, L., and Ikonen, E.: Spectral irradiance measurements of tungsten lamps with filter radiometers in the spectral range 290 nm to 900 nm, Meteorologia, 37, 305–312, 2000. Kyrö, E.: Spectral Lamp and HeCd-Laser Measurements, in: The Nordic Intercomparison of Ultraviolet and Total Ozone Instruments at Izaña, October 1996. Final report., edited by: Kjeldstad, B., Johnsen, B., and Koskela, T., 36, Meteorologisia julkaisuja\/, 79–88, Ilmatieteen laitos, helsinki, 1997. Kyrö, E., Taalas, P., Jörgensen, T., Knudsen, B., Stordal, F., Braahten, G., Dahlback, A., Neuber, R.and~Krüger, B., Dorokhov, V., Yushkov, V., Rudakov, V., and Torres, A.: Analysis of the ozone soundings made during the first quarter of 1989 in the Arctic, J. Geophys. Res., 8083–8091, 1992. Lakkala, K., Kyrö, E., and Turunen, T.: Spectral UV Measurements at Sodankylä during 1990-2001, J. Geophys. Res., 108, \doi10.1029/2002JD003300, 2003. Lakkala, K., Redondas, A., Meinander, O., Torres, C., Koskela, T., Cuevas, E., Taalas, P., Dahlback, A., Deferrari, G., Edvardsen, K., and Ochoa, H.: Quality assurance of the solar UV network in the Antarctic, J. Geophys. Res., 110, \doi10.1029/2004JD005584, 2005. Landelius, T. and Josefsson, W.: Methods for cosine correction of broadband UV data and their effect on the relation between UV irradiance and cloudiness, J. Geophys. Res., 105, 4795–4802, 2000. Lindfors, A., Kaurola, J., Arola, A., Koskela, T., Lakkala, K., Josefsson, W., Olseth, J A., and Johnsen, B.: A method for reconstruction of past UV radiation based on radiative transfer modeling: applied to four stations in northern Europe, J. Geophys. Res., 112, \doi10.1029/2007JD008454, 2007. Lindfors, A V., Arola, A., Kaurola, J., Taalas, P., and Svenøe, T.: Long-term erythemal UV doses at Sodankylä estimated using total ozone, sunshine duration, and snow depth, J. Geophys. Res., 108, \doi10.1029/2002JD003325, 2003. Mayer, B. and Kylling, A.: Technical note: the libRadtran software package for radiative transfer calculations-Description and examples of use, Atmos. Chem. Phys., 5, 1855–1877, 2005. Meinander, O., Josefsson, W., Kaurola, J., Koskela, T., and Lakkala, K.: Spike detection and correction in Brewer spectroradiometer UV spectra, Opt. Eng., 42, 1812–1819, 2003. Meinander, O., Kazadzis, S., Blumthaler, M., Ylianttila, L., Johnsen, B., Lakkala, K., Koskela, T., and Josefsson, W.: Diurnal discrepancies in spectral solar UV radiation measurements, Appl. Optics, 45, 5346–5357, 2006. Seckmeyer, G. and Bernhard, G.: Cosine Error Correction of spectral UV-irradiances, Atmospheric Radiation, 2049, 140/SPIE, 1993. Seckmeyer, G., Bais, A., Bernhard, G., Blumthaler, M., Booth, C., Disterhoft, P., Eriksen, P., McKenzie, R., Miyauchi, M., and Roy, C.: Instruments to Measure Solar Ultraviolet Radiation, Part 1: Spectral instruments, Tech. Rep. 125, WMO TD 1066, 2002. Slaper, H. and Koskela, T.: Methodology of intercomparing spectral sky measurements, in: The Nordic Intercomparison of Ultraviolet and Total Ozone Instruments at Izaña, October 1996. Final Report., edited by: Kjeldstad, B., Johnsen, B., and Koskela, T., 36, Meteorologisia julkaisuja\/, 89–108, Ilmatieteen laitos, Helsinki, 1997. Slaper, H., Reinen, H. A. J M., Blumthaler, M., Huber, M., and Kuik, F.: Comparing ground-level spectrally resolved solar UV measurements using various instruments: A technique resolving effects of wavelength shift and slit width, Geophys. Res. Lett., 22, 2721–2724, 1995. Tanskanen, A., Lindfors, A., Määttä, A., Krotkov, N., Herman, J., Kaurola, J., Koskela, T., Lakkala, K., Fioletov, V., Bernhard, G., McKenzie, R., Kondo, Y., O'Neill, M., Slaper, H., den Outer, P., Bais, A F., and Tamminen, J.: Validation of daily erythemal doses from Ozone Monitoring Instrument with ground-based UV measurement data, J. Geophys. Res., 112, \doi10.1029/2007JD008830, 2007. Thorseth, T., Kjeldstad, B., Johnsen, B., Blumenthaler, M., Lakkala, K., and Slaper, H.: Results from the Nordic Intercomparison of ultraviolet spectroradiometers in Sweden 2000, in: Geophysical Research Abstracts. Abstracts of the Contributions of the 27th General Assembly of the European Geophysical Society, Nice, France, 21–26 April 2002., 4, 2002. Von~der Gathen, P., Rex, M., Harris, N. R P., Lucic, D., Knudsen, B M., Braathen, G O., de~Backer, H., Fabian, R., Fast, H., Gil, M., Kyrö, E., Mikkelsen, I S., Rummukainen, M., Staehelin, J., and Varotsos, C.: Observational evidence for chemical ozone depletion over the Arctic in winter 1991–92, Nature, 375, 131–134, 1995. Weatherhead, E., Theisen, D., Stevermer, A., Enagonio, J., Rabinovitch, B., Disterhoft, P., Lantz, K., Meltzer, R., Sabburg, J.and~DeLuisi, J., Rives, J., and Shreffler, J.: Temperature dependence of the Brewer ultraviolet data, J. Geophys. Res., 106, 34 121–34 129, 2001. Webb, A., Gardiner, B., Martin, T., Leszcynski, K., Metzdorf, J., and Mohnen, V.: Guidelines for Site Quality Control of UV Monitoring, Tech. Rep. 126, World Meteorological Organization, Global Atmosphere Watch, 1998. Webb, A., Gardiner, B., Leszczynski, K., Mohnen, V., Johnston, P., Harrison, N., and Bigelow, D.: Quality Assurance in Monitoring Solar Ultraviolet Radiation: the State of the Art, Tech. Rep. 146, World Meteorological Organization, Global Atmosphere Watch, 2003. Wehrli, C.: Calibrations of Filter Radiometers for Determination of Atmospheric Optical Depth, Meteorologia, 37, 419–422, 2000. WMO: Scientific Assessment of Stratospheric ozone: 1989. Report No. 20 in 2 volumes, World Meteorological Organization, Geneva, 1990. Ylianttila, L. and Schreder, J.: Temperature effects of PTFE diffusers, Optical Materials, 27, 1811–1814, \doi10.1016/j.optmat.2004.11.008, 2005. Young, A., Björn, L., Moan, J., and Nultsch, W.: Environmental UV Photobiology, Plenum Press, New York, 1993.