ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-4799-2008 Comparison of UV irradiance measurements at Summit, Greenland; Barrow, Alaska; and South Pole, Antarctica Bernhard G. 1 Booth C. R. 1 Ehramjian J. C. 1 Biospherical Instruments, San Diego, USA 19 08 2008 8 16 4799 4810 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/8/4799/2008/acp-8-4799-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/4799/2008/acp-8-4799-2008.pdf

An SUV-150B spectroradiometer for measuring solar ultraviolet (UV) irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska, and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs) are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds attenuate irradiance at 345 nm at both sites by less than 6% on average, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at Summit by 4–6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20–80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10–25% smaller than in the summer. Maximum UV Indices ever observed at Summit, Barrow, and South Pole are 6.7, 5.0, and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9–2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow.

 References Andersen, S. B. and Knudsen, B. M.: The influence of polar vortex ozone depletion on NH mid-latitude ozone trends in spring, Atmos. Chem. Phys., 6, 2837–2845, 2006. Arctic Climate Impact Assessment (ACIA), Cambridge University Press, New York, USA, 1042 pp., 2005. Bernhard, G., Booth, C. R., and McPeters, R. D.: Calculation of total column ozone from global UV spectra at high latitudes. J. Geophys. Res., 108(D17), 4532, doi:10.1029/2003JD003450, 2003. Bernhard, G., Booth, C. R., and Ehramjian, J. C.: Version 2 data of the National Science Foundation's Ultraviolet Radiation Monitoring Network – South Pole, J. Geophys. Res., 109, D21207, doi:10.1029/2004JD004937, 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 Foundation's ultraviolet monitoring network, Optical Engineering, 44(4), 041011-1-041011-12, 2005. Bernhard, G., Booth, C. R., Ehramjian, J. C., and Quang, V. V.: NSF Polar Programs UV Spectroradiometer Network 2004–2005, Operations Report Volume 14.0, Biospherical Instruments Inc., San Diego, USA, available at: www.biospherical.com/NSF, 2006. Bernhard, G., Booth, C. R., Ehramjian, J. C., Stone, R., and Dutton, E. G.: Ultraviolet and visible radiation at Barrow, Alaska: Climatology and influencing factors on the basis of version 2, National Science Foundation network data, J. Geophys. Res., 112, D09101, doi:10.1029/2006JD007865, 2007. Bodhaine, B. A. and Dutton, E. G.: A long-term decrease in Artic haze at Barrow, Alaska, Geophys. Res. Lett., 20, 947–950, 1993. Booth, C. R., Lucas, T. B., Morrow, J. H., Weiler, C. S., and Penhale, P. A.: The United States National Science Foundation's polar network for monitoring ultraviolet radiation, in: Ultraviolet Radiation in Antarctica: Measurement and Biological Effects, Antarct. Res. Ser., 62, edited by: Weiler, C. S. and Penhale, P. A., AGU, Washington D.C., USA, 17–37, 1994. Cockell, C. S., Scherer, K., Horneck, G., Rettberg, P., Facius, R., Gugg-Helminger, A., Driscoll, C., and Lee, P.: Exposure of Arctic field scientists to ultraviolet radiation evaluated using personal dosimeters, Photochem. Photobiol., 74(4), 570–578, 2001. de Gruijl, F. R., Longstreth, J., Norval, M., Cullen, A. P., Slaper, H., Kripke, M. L., Takizawag, Y., and van der Leun, J. C.: Health effects from stratospheric ozone depletion and interactions with climate change, Photochem. Photobiol. Sci., 2, 16–28, 2003. Engelsen, O., Brustad, M., Aksnes, L., and Lund, E.: Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness, Photochem. Photobiol., 81, 1287–1290, 2005. Feng, W., Chipperfield, M. P., Davies, S., von der Gathen, P., Kyrö, E., Volk, C. M., Ulanovsky, A., and Belyaev, G.: Large chemical ozone loss in 2004/2005 Arctic winter/spring, Geophys. Res. Lett., 34, L09803, doi:10.1029/2006GL029098, 2007. Fioletov, V. E., Kerr, J. B., Wardle, D. I., Davies, J., Hare, E. W., McElroy, C. T., and Tarasick, D. W.: Long-term ozone decline over the Canadian Arctic to early 1997 from ground-based and balloon observations, Geophys. Res. Lett., 24(22), 2705–2708, 1997. Fioletov, V. E., McArthur, L. J. B., Kerr, J. B., and Wardle, D. I.: Long-term variations of UV-B irradiance over Canada estimated from Brewer observations and derived from ozone and pyranometer measurements, J. Geophys. Res., 106(D19), 23 009–23 028, 2001. Grant, W. B.: An estimate of premature cancer mortality in the US due to inadequate doses of solar ultraviolet-B radiation, Cancer, 94(6), 1867–1875, 2002. Grenfell, T. C., Warren, S. G., and Mullen, P. C.: Reflection of solar radiation by the Antarctic snow surface at ultraviolet, visible, and near infrared wavelengths, J. Geophys. Res., 99(D9), 18 669–18 684, 1994. Holick, M.: Vitamin D and Bone Health, J. Nutr., 126, 1159S–1164S, 1996. Holton, J. R., Haynes, P. H., McIntyre, M. E., Douglass, A. R., Rood, R. B., and Pfister, L.: Stratosphere-troposphere exchange, Rev. Geophys., 33(4), 403–440, 1995. Iqbal, M.: An introduction to solar radiation, Academic Press, New York, USA, 390 pp., 1983. Knudsen, B. M. and Andersen, S. B.: Longitudinal variation in springtime ozone trends, Nature, 413, 699–700, 2001. Lakkala, K., Kyrö, E., and Turunen, T.: Spectral UV measurements at Sodankylä during 1990–2001, J. Geophys. Res., 108(D19), 4621, doi:10.1029/2002JD003300, 2003. Lehmann, B.: The vitamin D3 pathway in human skin and its role for regulation of biological processes, Photochem Photobiol., 81(6),1246–1251, 2005. Mahesh, A., Walden, V. P., and Warren, S. G.: Ground-based infrared remote sensing of cloud properties over the Antarctic plateau – Part 2: Cloud optical depths and particle sizes, J. Appl. Meteorol., 40, 1279–1294, 2001. Manney, G. L., Santee, M. L., Froidevaux, L., Hoppel, K., Livesey, N. J., and Waters, J. W.: EOS MLS observations of ozone loss in the 2004–2005 Arctic winter, Geophys. Res. Lett., 33, L04802, doi:10.1029/2005GL024494, 2006. 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. McKinlay, A. F. and Diffey, B. L.: A reference action spectrum for ultraviolet induced erythema in human skin, in: Commission International de l'Éclairage (CIE), Research Note, 6(1), 17–22, 1987. Newman, P. A., Gleason, J. F., McPeters, R. D., and Stolarski, R. S.: Anomalously low ozone over the Arctic, Geophys. Res. Lett., 24(22), 2689–2692, 1997. Nichol, S. E., Pfister, G., Bodeker, G. E., McKenzie, R. L., Wood, S. W., and Bernhard, G.: Moderation of cloud reduction of UV in the Antarctic due to high surface albedo, J. Appl. Meteorol., 42(8), 1174–1183, 2003. Rex, M., Salawitch, R. J., von der Gathen, P., Harris, N. R. P., Chipperfield, M. P., and Naujokat, B.: Arctic ozone loss and climate change, Geophys. Res. Lett., 31, L04116, doi:10.1029/2003GL018844, 2004. Stokstad, E.: Nutrition: the vitamin D deficit, Science, 302, 1886–1888, 2003. Taalas, P., Kaurola, J., Kylling, A., Shindell, D., Sausen, R., Dameris, M., Grewe, V., Herman, J., Damski, J., and Steil B.: The impact of greenhouse gases and halogenated species on future solar UV radiation doses, Geophys. Res. Lett., 27(8), 1127–1130, 2000. United Nations Environmental Program (UNEP): Environmental effects of ozone depletion and its interactions with climate change: 2002 assessment; executive summary, Photochem. Photobiol. Sci., 2, 1–4, 2003. Uttal, T., Makshtas, A., Paatero, J., Hansen, G., and Intrieri, J.: A new climate observatory facility in Tiksi, Russia, Geophys. Res. Abstr., 9, 11193, 2007. Webb, A. R., Kline, L., and Holick, M. F.: Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin, J. Clin. Endocrinol. Metab., 67(2), 373–378, 1988. World Health Organization (WHO): Global Solar UV Index: A Practical Guide, Geneva, Switzerland, available at: http://www.unep.org/PDF/Solar_Index_Guide.pdf, 2002. World Meteorology Organisation (WMO): Scientific assessment of ozone depletion: 2006, Global Ozone Res. Monit. Proj., Rep. 50, Geneva, Switzerland, 2007. Wuttke, S., Schrems, O., Seckmeyer, G., and Hanken, T.: Spectral measurement of UV irradiance in polar Regions, European Geosciences Union, Geophys. Res. Abstr., 7, 08419, 2005. Wuttke, S., Seckmeyer, G., Bernhard, G., Ehramjian, J., McKenzie, R., Johnston, P., and O'Neil, M.: New spectroradiometers complying with the NDSC standards, J. Atmos. Ocean. Technol., 23(2), 241–251, 2006.