Surface Ultraviolet Radiation

Surface Ultraviolet Radiation J.B. Kerr1 and V.E. Fioletov2, * 1Cowichan

Bay, BC V0R 1N2 Canada, 4905 Dufferin Street Toronto ON M3H 5T4

2Environment

[Original manuscript received 17 May 2007; accepted 5 September 2007]

One of the main concerns regarding a decrease in stratospheric ozone is the consequential increase in the amount of ultraviolet (UV) radiation that reaches the lower atmosphere and the Earth’s surface. Radiation at UV wavelengths where ozone absorbs strongly is detrimental to most biological species, including human beings, so a decrease in stratospheric ozone could have a significant impact on the biosphere. This concern has led to a significant increase in surface UV radiation research over the last two decades since the ratification of the Montreal Protocol. Studies include investigations into understanding the complicated absorption and scattering processes involved in the radiative transfer of UV through the atmosphere as well as research on the impacts of changes in UV radiation. Factors affecting surface UV radiation will be discussed, resources used to study surface UV radiation will be described and progress made in our understanding of surface UV radiation over the past two decades will be reviewed.

ABSTRACT

RÉSUMÉ [Traduit par la rédaction] L’une des principales inquiétudes concernant une diminution de l’ozone stratosphérique est l’augmentation consécutive de la quantité de rayonnement ultraviolet (UV) qui atteint la basse atmosphère et la surface de la terre. Le rayonnement de longueurs d’onde UV dans la région où il se trouve fortement absorbé par l’ozone est préjudiciable à la plupart des espèces biologiques, y compris les êtres humains, de sorte qu’une diminution de l’ozone stratosphérique pourrait avoir des conséquences importantes sur la biosphère. Cette inquiétude a mené à une augmentation importante de la recherche sur le rayonnement UV à la surface au cours des deux dernières décennies, depuis la ratification du Protocole de Montréal. Les études comprennent des investigations visant à comprendre les processus compliqués d’absorption et de diffusion qui jouent un rôle dans le transfert radiatif de l’UV à travers l’atmosphère de même que des recherches sur les conséquences de changements dans le rayonnement UV. Nous discuterons des facteurs ayant une influence sur le rayonnement UV à la surface, nous décrirons les ressources utilisées pour étudier le rayonnement UV à la surface et nous examinerons les progrès réalisés dans la compréhension du rayonnement UV à la surface au cours des deux dernières décennies.

1 Introduction Solar ultraviolet (UV) radiation at the Earth’s surface passes through the atmosphere where many complicated absorption and scattering processes occur. In general, radiation at progressively shorter UV wavelengths becomes increasingly harmful to most biological species. UV radiation is classified as UV-A (315–400 nm), UV-B (280–315 nm), and UV–C (100–280 nm). Atmospheric gases absorb very little UV-A radiation. Atmospheric oxygen and ozone absorb all UV-C radiation and prevent it from reaching the troposphere and the Earth’s surface. Absorption by ozone increases rapidly with decreasing UV-B wavelength and causes surface radiation to fall off sharply with decreasing wavelength, as illustrated in Fig. 1. The intensity of UV-B radiation reaching the ground and the short wavelength cut-off of solar radiation at about

290 nm are strongly dependent on the amount of ozone present in the atmosphere. Knowledge of the intensity, wavelength dependence, and angular distribution of UV radiation at the Earth’s surface is important for several reasons. The evolution and growth of most terrestrial and aquatic life forms, including human beings, are influenced by many environmental variables, including the intensity of UV irradiance at the Earth’s surface or under water. In human beings, excessive accumulated exposure can cause sunburn, skin cancer, eye cataracts, or suppression of the immune system (UNEP, 2006). Most biological systems respond to UV radiation with effects that generally become more detrimental with decreasing wavelength. The specific sensitivity to UV radiation for a particular life

*Corresponding author’s e-mail: [email protected] ATMOSPHERE-OCEAN 46 (1) 2008, 159–184 doi:10.3137/ao.460108 Canadian Meteorological and Oceanographic Society

160 / J.B. Kerr and V.E. Fioletov

–1) Spectral Irradiance (W(Watts/m m–2 nm2/nm) SPECTRAL IRRADIANCE

SURFACE

0.1000

10

SUNBURNING ACTION SPECTRUM

0.0100

0.0010

-1

SPACE

1.0000

Ozone Coefficient (cm–1) (cm ) OZONEAbsorption ABSORPTION COEFFICIENT

15

5

OZONE ABSORPTION 0 290 295 300 305 310 315 320 325 330 335 340 345 350

Wavelength (nm)

Fig. 1

Ultraviolet radiation measured from space (black) and on the ground at noon during the summer (blue). Absorption by stratospheric ozone is the main cause for the decrease by several orders of magnitude with decreasing wavelength. Also shown is the erythemal action spectrum illustrating that sunburning potential increases with decreasing wavelength. In general, most biological species show increasing sensitivity with decreasing wavelength in the UV-B.

form is quantified by an action spectrum such as that for erythema (skin reddening) in human beings (McKinlay and Diffey, 1987), plant damage (Caldwell et al., 1986), and DNA damage (Setlow, 1974). For example, the sunburning action spectrum is shown in Fig. 1. There is also emerging evidence that UV-B radiation can be beneficial to human health through the production of Vitamin D. A number of studies have linked low solar UV radiation exposure to a higher risk of some internal cancers, such as colorectal and prostate, and autoimmune diseases, such as multiple sclerosis and type 1 diabetes (Young and Walker, 2005; UNEP, 2006). In addition, manufactured materials such as plastics are sensitive to exposure to UV radiation, and significant research is carried out to develop UV-resistant materials intended for outdoor use. UV radiation also drives photochemical reactions in the atmosphere and is therefore important for tropospheric pollution studies. The environment of UV radiation at the Earth’s surface and under water depends on many complicated absorption and

scattering processes that occur in the atmosphere, at the Earth’s surface, and under water. Surface radiation absorbed by a particular atmospheric gas has wavelength-dependent structure with features that are similar to the absorption spectrum of the constituent. The most significant atmospheric absorber at UV-B wavelengths is stratospheric ozone and the wavelength structure is seen in ground-based measurements (Kerr and McElroy, 1993). Absorption by airborne aerosols such as smoke from forest fires (McArthur et al., 1999), biomass burning (Kirchoff et al., 2001), or desert dust (di Sarra et al., 2002) generally has little wavelength-dependent structure and absorption usually increases with decreasing wavelength. Scattering processes in the atmosphere include molecular (Rayleigh) scattering and scattering by larger particles such as cloud constituents and aerosols. Downwelling surface UV radiation is also enhanced by increased surface albedo, which returns radiation upwards to the atmosphere where it is partially scattered back to the ground. In general, the albedo of most surfaces for UV radiation is about 4%

ATMOSPHERE-OCEAN 46 (1) 2008, 159–184 doi:10.3137/ao.460108 La Société canadienne de météorologie et d’océanographie

Surface Ultraviolet Radiation / 161 (Herman and Celarier, 1997). The main cause for increased albedo is snow, which can increase surface albedo to more than 95% at polar plateaus (Grenfell et al., 1994) and downwelling UV radiation by more than 50% (Bernhard et al., 2007). Also, if clouds are present below a high-altitude observation site, the effects of increased albedo from clouds become important (McKenzie et al., 2001a). Historically, researchers in Canada have made important contributions to UV radiation studies. The Brewer spectrophotometer was developed in Canada (Kerr et al., 1985) and is now the most commonly used spectral UV radiation scanning instrument in the world. Canada’s operational spectral UV radiation network (Kerr, 1994) is highly regarded by the international scientific community as one of the most reliable networks and has been the source of data for many scientific studies. The Canadian UV Index was introduced in Canada in 1992 (Kerr et al., 1994) and is now recognized by the World Meteorological Organization (WMO) and World Health Organization (WHO) as the standard public awareness indicator for UV radiation levels. 2 Variables that affect UV radiation It is important to have a good understanding of the processes that affect UV irradiance in order to develop useful operational products. These products include UV Index forecasting techniques developed in several countries (Burrows et al., 1994; Long et al., 1996; Lemus-Deschamps et al., 1999), the estimation of surface UV irradiance using satellite data (Eck et al., 1995; Verdebout, 2000; Krotkov et al., 2002), and the estimation of UV radiation penetration under water from space-based measurements (Vasilkov et al., 2002). Detailed understanding of the processes affecting surface irradiance is also important for estimating UV irradiance levels before measurements were made. This allows for the extension of records into the past using satellite data (Herman et al., 1996) and ground-based records of other variables (Fioletov et al., 2001). Also, estimates can be made of the past spatial climatology of surface UV radiation over wide areas (Fioletov et al., 2003; 2004; Lindfors and Vuilleumier, 2005) and of future UV radiation using expectations of future changes in atmospheric ozone and other variables (Taalas et al., 2000). Surface UV radiation is defined as downward irradiance falling on a horizontal surface. Radiation falling on the horizontal surface is divided into the direct component, which is from the sun, and the diffuse component, which is scattered from the sky. Global irradiance is the sum of the direct and diffuse components. The contribution of sky radiance from any given direction is proportional to the cosine of the angle between the zenith and the direction of incidence. Most ground-based instruments are designed to measure global irradiance, and some are capable of measuring both direct and diffuse radiation by using a shadow-band or other solar pointing method. The UV irradiance at the Earth’s surface at all wavelengths is directly proportional to that of the solar spectrum. Other factors that affect the intensity and angular distribution of sur-

face UV sky radiance are geometrical and geophysical variables. The geometrical variables are the distance between the Earth and sun and the solar zenith angle of the sun. Geophysical variables include atmospheric constituents that absorb or scatter radiation as it passes through the atmosphere and substances that scatter radiation at the Earth’s surface. The absorbing variables include ozone, nitrogen dioxide, sulphur dioxide, and absorbing aerosols; the scattering variables include air molecules, clouds, non-absorbing aerosols, and snow, ice or vegetation at the Earth’s surface. a The Solar Spectrum Solar radiation is important for nearly all studies regarding the Earth’s geophysical properties and biological activities. The solar spectrum is used as input for radiative transfer, dynamical, and photochemical models that simulate the real atmosphere. The absolute intensity of surface UV irradiance at a given wavelength is proportional to the radiative output from the sun at the same wavelength. Therefore, spectral features of the solar spectrum are present in surface UV irradiance, as illustrated in Fig. 1, which compares space-based measurements of the solar spectrum with ground-based measurements of surface UV irradiance. Traditionally, the method for estimating the solar spectrum outside the Earth’s atmosphere has been the ground-based Langley plot method (Neckel and Labs, 1984). However, this method is limited by the fact that no radiation at wavelengths shorter than 290 nm reaches the Earth’s surface and the uncertainty in the measured extraterrestrial value for wavelengths shorter than about 300 nm is large because of the small signal due to absorption by ozone and molecular oxygen. Radiation below 300 nm is an important driver for many atmospheric photochemical processes, so knowledge of the solar spectrum at these wavelengths is important for photochemical model studies. More recently, satellite instruments have measured the absolute intensity of the solar spectrum (Cebula et al., 1996; Thuillier et al., 2004) with an estimated accuracy of ±3%. Comparisons of the solar spectrum measured from different satellite instruments agree to within ±3%, a value that is similar to results of comparisons between direct space-based measurements and ground-based Langley plot measurements (Bais, 1997; Gröbner and Kerr, 2001). Multi-year records of satellite data have also allowed the direct measurement of variations in irradiance at UV-C wavelengths over the 11-year solar cycle. It has been found that the intensity of solar radiation for wavelengths between 245 and 250 nm is about 6–8% higher when solar activity is at a maximum than at a solar minimum (DeLand et al., 2004) and even larger (approximately 9%) for wavelengths between 200 and 205 nm (Floyd et al., 2003). However, the variability in the UV-A and UV-B radiation has been found to be relatively small (6

200 150 100 UV Index>7

50 0 250 O

O

Number of Hours

Edmonton (54 N, 114 W)

UV Index>5

200 150 100 UV Index>6

50 0 100

O

O

Number of Hours

Churchill (59 N, 94 W) 80 UV Index>5

60 40 20 UV Index>6

0 .

1965 1970 1975 1980 1985 1990 1995 2000 2005

Fig. 11 The number of hours per year that the UV Index was above 6 and 7 at Toronto and above 5 and 6 at Edmonton and Churchill. The numbers are from the reconstructed data sets for Toronto, Churchill, and Edmonton (updated from Fioletov et al. (2001)).

ATMOSPHERE-OCEAN 46 (1) 2008, 159–184 doi:10.3137/ao.460108 Canadian Meteorological and Oceanographic Society

180 / J.B. Kerr and V.E. Fioletov Overall, the wealth of knowledge and data gained over the last 20 years has improved the certainty and confidence with which we can address the ozone depletion problem and its relation to changes in surface UV radiation.

Acknowledgements The authors wish to thank three anonymous reviewers for providing many constructive comments and suggestions for the paper.

References AROLA, A.; J. KAUROLA, L. KOSKINEN, A. TANSKANEN, T. TIKKANEN, P.

and V. FIOLETOV. 2003. A new approach to estimating the albedo for snow-covered surfaces in the satellite UV method. J. Geophys. Res. 108: doi:10.1029/2003JD003492. AROLA, A.; S. KAZADZIS, N. KROTKOV, A. BAIS, J. GRÖBNER and J.R. HERMAN. 2005. Assessment of TOMS UV bias due to absorbing aerosols, J. Geophys. Res. 110: D23211, doi:10.1029/2005JD005913. BAIS, A.F. 1997. Absolute spectral measurements of direct solar ultraviolet irradiance with a Brewer spectrophotometer. Appl. Opt. 36: 5199–5204. TAALAS, J.R. HERMAN, N. KROTKOV

BAIS, A.F.; S. MADRONICH, J. CRAWFORD, S.R. HALL, B. MAYER, M. VAN WEELE, J. LENOBLE, J.G. CALVERT, C.A. CANTRELL, R.E. SHETTER, A. HOFZUMAHAUS, P. KOEPKE, P.S. MONKS, G. FROST, R. MCKENZIE, N. KROTKOV, A. KYLLING, W.H. SWARTZ, S. LLOYD, G. PFISTR, T.J. MARTIN, E.-P. ROETH, E. GRIFFIOEN, A. RUGGABER, M. KROL, A. KRAUS, G.D. EDWARDS, M. MUELLER, B.L. LEFER, P. JOHNSTON, H. SCHWANDER, D. FLITTNER, B.G. GARDINER, J.

and R. SCHMITT. 2003. International Photolysis Frequency Measurement and Model Intercomparison (IPMMI): Spectral actinic solar flux measurements and modeling. J. Geophys. Res. 108: 8543, doi:10.1029/2002JD002891. BAIS, A.F.; A. KAZANTZIDIS, S. KAZADZIS, D.S. BALIS, C.S. ZEREFOS and C. MELETI. 2005. Deriving an effective aerosol single scattering albedo from spectral surface UV irradiance measurements. Atmos. Environ. 39: 1093–1102. BAIS, A.F.; and D. LUBIN (Lead Authors), A. AROLA, G. BERNHARD, M. BARRICK

BLUMTHALER, N. CHUBAROVA, C. ERLICK, H.P. GIES, N. KROTKOV, K. LANTZ, B. MAYER, R.L. MCKENZIE, R.D. PIACENTINI, G. SECKMEYER, J.R.

and C.S. ZEREFOS. 2007. Surface Ultraviolet Radiation: Past, Present, and Future. In: Scientific Assessment of Ozone Depletion: 2006, Chapter 7, Global Ozone Research and Monitoring Project – Report No. 50, World Meteorological Organization, Geneva, 54 pp.

SLUSSER

Penhale (Eds), AGU Antarctic Research Series, 62, American Geophysical Union, Washington, DC, pp. 17–37. BOOTH, C.R.; G. BERNHARD, J.C. EHRAMJIAN, V.V. QUANG and S.A. LYNCH. 2001. NSF Polar Programs UV Spectroradiometer Network 1999-2000 Operations Report. Biospherical Instruments Inc., San Diego, CA, 219 pp. BORKOWSKI, J.L. 2000. Homogenization of the Belsk UV-B series (1976–1997) and trend analysis. J. Geophys. Res. 105: 4873–4878. BRASSEUR, A.L.; R. RAMAROSON, A. DELANNOY, W. SKAMAROCK and M. BARTH. 2002. Three-dimensional calculation of photolysis frequencies in the presence of clouds and impact on photochemistry. J. Atmos. Chem. 41: 211–237. BREWER, A.W.; C.T. MCELROY and J.B. KERR. 1973. Nitrogen dioxide concentrations in the atmosphere. Nature, 246: 129–133. BURROWS, W.R. 1997. CART regression models for predicting UV radiation at the ground in the presence of cloud and other environmental factors. J. Appl. Meteorol. 36: 531–544. BURROWS, W.R.; M. VALLÉE, D.I. WARDLE, J.B. KERR, L.J. WILSON and D.W. TARASICK. 1994. The Canadian operational procedure for forecasting total ozone and UV radiation. Meteorol. Appl. 1: 247–265. CALBÓ, J.; D. PAGES and J. GONZALEZ. 2005. Empirical studies of cloud effects on UV radiation: A review. Rev. Geophys. 43: RG2002, doi:10.1029/2004RG000155. CALDWELL, M.M.; L.B. CAMP, C.W. WARNER and S.D. FLINT. 1986. Action spectra and their key role in assessing biological consequences of solar UV-B radiation change. In: Stratospheric Ozone Reduction, Solar Ultraviolet Radiation and Plant Life. Worrest, R.C. and M.M. Caldwell (Eds), Springer-Verlag, Berlin, pp. 87–111. CAHALAN R.F.; L. OREOPOULOS, A. MARSHAK, K.F. EVANS, A.B. DAVIS, T.P. ACKERMAN, H.W. BARKER, E.E. CLOTHIAUX, R.G. ELLINGSON, M.J. GARAY, E. KASSIANOV, S. KINNE, A. MACKE, W. O’HIROK, P.T. PARTAIN, S.M. PRI-

BALIS, D.S.; V. AMIRIDIS, C. ZEREFOS, A. KAZANTZIDIS, S. KAZADZIS, A.F. BAIS,

GARIN, A.N. RUBLEV, G.L. STEPHENS, F. SZCZAP, E.E. TAKARA, T. VÁRNIA, G.

and M.O. ANDREAE. 2004. Study of the effect of different type of aerosols on UV-B radiation from measurements during EARLINET. Atmos. Chem. Phys. 4: 307–321. BATES, D.R. 1984. Rayleigh scattering by air. Planet. Space Sci. 32: 785–790. BEATTIE, B.; K. KEDDY, D. TARASICK and J. KERR. 1995. Pre-1980 Ultraviolet Index climatology for Canadian locations. Report MAES 1-95, Environment Canada, Atlantic Region, 32 pp. BERNHARD, G.; C.R. BOOTH and J.C. EHRAMJIAN. 2005. Real-time ultraviolet and column ozone from multichannel ultraviolet radiometers deployed in the National Science Foundation’s ultraviolet monitoring network. Opt. Eng. 44: 1–12. BERNHARD, G.; C.R. BOOTH, J.C. EHRAMJIAN, R. STONE and E.G. DUTTON. 2007. 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: doi:10.1029/2006JD007865. BODHAINE, B.A.; E.G. DUTTON D.J. HOFMANN, R.L. MCKENZIE and P.V. JOHNSTON. 1997. Spectral UV measurements at Mauna Loa: July 1995–July 1996. J. Geophys. Res. 102: 19265–19273. BODHAINE, B.A.; N.B. WOOD, E.G. DUTTON and J.R. SLUSSER. 1999. On Rayleigh optical depth calculations. J. Atmos. Oceanic Technol. 19: 1854–1861. BOOTH, C.R.; T.B. LUCAS, J.H. MORROW, C.S. WEILER and P.A. PENHALE. 1994. The United States National Science Foundation/Antarctic program’s network for monitoring ultraviolet radiation. In: Ultraviolet Radiation in Antarctica: Measurements and Biological Research, C.S. Weiler and P.A.

WEN and T.B. ZHURAVLEVE. 2005. THE I3RC: Bringing together the most advanced radiative transfer tools for cloudy atmospheres. Bull. Am. Meteorol. Soc. 86: 1275–1293.

C. MELETI, E. GERASOPOULOS, A. PAPAYANNIS, V. MATTHIAS, H. DIER

CEBULA, R.P.; G.O. THUILLET, M.E. VAN-HOOSIER, E. HILSENRATH, M. HERSÉ,

and P.C. SIMON. 1996. Observations of the solar irradiance in the 200–350 nm interval during the ATLAS-1 mission: a comparison among three sets of measurements – SSBUV, SOLSPEC, and SUSIM. Geophys. Res. Lett. 23: 2289–2292. CEDE, A.; M. BLUMTHALER, E. LUCCINI, R.D. PIACENTINI and L. NUMEZ. 2002. Effects of clouds on erythemal and total irradiance as derived from data of the Argentine Network. Geophys. Res. Lett. 29: doi:10.1029/ 2002GL015708. CEDE A. and J. HERMAN. 2005. Measurements of O3, SO2, NO2, and HCHO column amounts using a Brewer spectrophotometer. In: Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, Proc. SPIE, San Diego, USA, Slusser, J.R., J.R. Herman, and W. Gao, (Eds), SPIE. pp. 1–9. CEDE, A.; J. HERMAN, A. RICHTER, N. KROTKOV and J. BURROWS. 2006. Measurements of nitrogen dioxide total column amounts using a Brewer double spectrophotometer in direct sun mode. J. Geophys. Res. 111: doi: 10.1029/2005JD006586. CHIPPERFIELD, M.P.; and W.J. RANDEL (Lead Authors), G.E. BODEKER, M. G.E. BRUECKNER

DAMERIS, V.E. FIOLETOV, R.R. FRIEDL, N.R.P. HARRIS, J.A. LOGAN, R.D. MCPETERS, N.J. MUTHAMA, T. PETER, T.G. SHEPHERD, K.P. SHINE, S. SOLOMON, L.W. THOMASON and J.M. ZAWADNY. 2003. Global ozone: Past and future. In: Scientific Assessment of Ozone Depletion: 2002. Global


Surface Ultraviolet Radiation / 181 Ozone Research and Monitoring Project – Report No. 47, World Meteorological Organization, Geneva, 91 pp. CHUBAROVA, N.E. 2004. Influence of aerosol and atmospheric gases on ultraviolet radiation in different optical conditions including smokey mist of 2002. Dokl. Earth Sci. 394: 62–67. CHUBAROVA, N.Y.; Y.I. NEZVAL, J. VERDEBOUT, N. KROTKOV and J. HERMAN. 2005. Long-term UV irradiance changes over Moscow and comparisons with UV estimates from TOMS and METEOSAT. In: Ultraviolet Groundand Space-based Measurements, Models, and Effects V, Proc. SPIE, San Diego, USA, J.R. Slusser and J.R. Herman, and W. Gao, (Eds), 31 July–4 August 2005, SPIE, pp. 1–11. DAVIS, J.M. and J.R. SLUSSER. 2005. New USDA UVB synthetic spectra algorithm. In: Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, Proc. SPIE, G. Bernhard, J.R. Slusser and W. Gao (Eds), 31 July–4 August 2005, SPIE, pp. 1–7. DELAND, M.T.; R.P. CEBULA and E. HILSENRATH. 2004. Observations of solar spectral irradiance change during cycle 22 from NOAA-9 Solar Backscatter Ultraviolet Model 2 (SBUV/2). J. Geophys. Res. 109: doi: 10.1029/2003JD004074. DEN OUTER, P.N.; H. SLAPER and R.B. TAX. 2005. UV radiation in the Netherlands: Assessing long-term variability and trends in relation to ozone and clouds. J. Geophys. Res. 110: doi:10.1029/2004JD004824. DIAZ, S.; G. DEFERRARI, D. MARTINIONI and A. OBERTO. 2001. Solar irradiances over Ushuaia (54.49°S, 68.19°W) and San Diego (32.45°N, 117.11°W) geographical and seasonal variation. J. Atmos. Sol.-Terr. Phys. 63: 309–320. DI SARRA, A.; M. CACCIANI, P. CHAMARD, C. CORNWALL, J.J. DELUISI, T. DI IORIO, P. DISTERHOFT, G. FIOCCO, D. FUÁ and F. MONTELEONE. 2002. Effects of desert dust and ozone on the ultraviolet irradiance at the Mediterranian island of Lampedusa during PAUR II. J. Geophys, Res. 107: doi: 10.1029/2000JD000139. DUBOVIK, O.; B.N. HOLDEN, T.F. ECK, A. SMIRNOV, Y.J. KAUFMAN, M.D. KING, D. TANRE and I. SLUTSKER. 2002. Variability of absorption and optical properties of key aerosol types observed in worldwide locations. J. Atmos. Sci. 59: 590–608. ECK, T.F.; P.K. BHARTIA and J.B. KERR. 1995. Satellite estimation of spectral UVB irradiance using TOMS derived total ozone and UV reflectivity. Geophys. Res. Lett. 22: 611–614. EVANS, K.F. 1998. The spherical harmonics discrete ordinate method for three-dimensional atmospheric radiative transfer. J. Atmos. Sci. 55: 429–446. FIOLETOV, V.E.; J.B. KERR and D.I. WARDLE. 1997. The relationship between total ozone and spectral UV irradiance and its use for deriving total ozone from UV measurements. Geophys, Res. Lett. 24: 2997–3000. FIOLETOV, V.E.; E. GRIFFIOEN, J.B. KERR, D.I. WARDLE and O. UCHINO. 1998. Influence of volcanic sulfur dioxide on spectral UV irradiance as measured by Brewer spectrophotometers. Geophys. Res. Lett. 25: 1665–1668. FIOLETOV, V.E.; L.J.B. MCARTHUR, J.B. KERR and D.I. WARDLE. 2001. Longterm variations of UV-B irradiance over Canada estimated from Brewer observations and derived from ozone and pyranometer measurements. J. Geophys. Res. 106: 23009–23027. FIOLETOV V.E.; J.B. KERR, D.I. WARDLE, N. KROTKOV and J.R. HERMAN. 2002. Comparison of Brewer ultraviolet irradiance measurements with total ozone mapping spectrometer satellite retrievals. Opt. Eng. 41: 3051–3061. FIOLETOV, V.E.; J.B. KERR, L.J.B. MCARTHUR, D.I. WARDLE and T.W. MATHEWS. 2003. Estimating UV Index climatology over Canada. J. Appl. Meteorol. 42: 417–433. FIOLETOV, V.E.; M.G. KIMLIN, N. KROTKOV, L.B.J. MCARTHUR, J.B. KERR, D.I. WARDLE, J.R. HERMAN, R. MELTZER, T.W. MATHEWS and J. KAUROLA. 2004. UV Index climatology over the United States and Canada from groundbased and satellite estimates. J. Geophys. Res. 109: doi: 10.1029/2004JD004820. FLIGGE, M. and S.K. SOLANKI. 2000. The solar spectral irradiance since 1700. Geophys. Res. Lett. 27: 2157–2160. FLOYD, L.E.; J.W. COOK, L.C. HERRING and P.C. CRANE. 2003. SUSIM’s 11-year observational record of the solar UV irradiance. Adv. Space Res. 31: 2111–2120.

and B. 2001. Direct-sun column ozone retrieval by the ultraviolet multifilter rotating shadow-band radiometer and comparison with those from Brewer and Dobson spectrophotometers. Appl. Opt. 40: 3149–3155. GLANDORF, M.; A. AROLA, A. BAIS and G. SECKMEYER. 2005. Possibilities to detect trends in spectral UV irradiance. Theor. Appl. Climatol. 81: 33–34. GAO, W.; J. SLUSSER, J. GIBSON, G. SCOTT, D. BIGELOW, J. KERR MCARTHUR.

GOERING, C.D.; T.S. L’ECUYER, G.L. STEPHENS, J.R. SLUSSER, G. SCOTT, J. DAVIS, J.C. BARNARD and S. MADRONICH. 2005. Simultaneous retrievals of column ozone and aerosol optical properties from direct and diffuse solar irradiance measurements. J. Geophys. Res. 110: doi:10.1029/2004JD005330. GRENFELL, T.C.; S.G. WARREN and P.C. MULLEN. 1994. Reflection of solar radiation by the Antarctic snow surface at ultraviolet, visible, and near infrared wavelengths. J. Geophys. Res. 99: 18669–18684. GRÖBNER, J.; D.I. WARDLE, C.T. MCELROY and J.B. KERR. 1998. Investigation of the wavelength accuracy of Brewer spectrophotometers. Appl. Opt. 37: 8352–8360. GRÖBNER, J. and J.B. KERR. 2001. Ground-based determinations of the spectral ultraviolet extraterrestrial solar irradiance: Providing a link between space-based and ground-based solar UV measurements. J. Geophys. Res. 106: 7211–7217. GRÖBNER, J. and C. MELETI. 2004. Aerosol optical depth in the UVB and visible wavelength range from Brewer spectrophotometer direct irradiance measurements: 1991–2002. J. Geophys. Res. 109: doi:10.1029/ 2003JD004409. HARRISON, L.; J. MICHALSKY and J. BERNDT. 1994. Automated multi-filter rotating shadow-band radiometer: an instrument for optical depth and radiation measurements. Appl. Opt. 33: 5118–5125. HARRISON, L.; J. BERNDT, P. KIEDRON and P. DISTERHOFT. 2002. United States Department of Agriculture reference ultraviolet spectroradiometer: current performance and operational experience at Table Mountain, Colorado. Opt. Eng. 41: 3096–3103. HERMAN, J.R.; P.K. BHARTIA, J. ZIEMKE, Z. AHMAD and D. LARKO. 1996. UV-B increases (1979–1992) from decreases in total ozone. Geophys. Res. Lett. 23: 2117–2120. HERMAN, J.R. and E.A. CELARIER. 1997. Earth surface reflectivity climatology at 340 nm to 380 nm from TOMS data. J. Geophys. Res. 102: 28003–28011. HERMAN, J.R.; N. KROTKOV, E. CELARIER, D. LARKO and G. LABOW. 1999. Distribution of UV radiation from TOMS-measured UV-backscattered radiances. J. Geophys. Res. 104: 12059–12076. HOFZUMAHAUS, A.; A. KRAUS, A. KYLLING and C.S. ZEREFOS. 2002. Solar actinic radiation (280–420 nm) in the cloud-free troposphere between ground and 12 km altitude: Measurements and model results. J. Geophys. Res. 107: 8139, doi:10.1029/2001JD000142. HOISKAR, B.A.K.; R. HAUGEN, T. DANIELSEN, A. KYLLING, K. EDVARDSEN, A. DAHLBACK, B. JOHNSEN, M. BLUMTHALER and J. SCHREDER. 2003. Multichannel moderate-bandwidth filter instrument for measurement of the ozone column amount, cloud transmittance, and ultraviolet dose rates. Appl. Opt. 42: 3472–3479. HUBER, M.; M. BLUMTHALER, J. SCHREDER, B. SCHALLHART and J. LENOBLE. 2004. Effect of inhomogeneous surface albedo on diffuse UV sky radiance at a high-altitude site. J. Geophys. Res. 109: doi:10.1029/2003JD004113. JOSEFSSON, W. 2006. UV-radiation 1983-2003 measured at Norrkoping, Sweden. Theor. Appl. Climatol. 83: 59–76. KERR, J.B. 1991. Trends in total ozone at Toronto between 1960 and 1991. J. Geophys. Res. 96: 20703–20709. KERR, J.B. 1994. Decreasing ozone causes health concern: How Canada forecasts ultraviolet-B radiation. Environ. Sci. Technol. 29: 514–518. KERR, J.B. 1997. Observed dependencies of atmospheric UV radiation and trends. In: NATO ASI Series, Vol. I 52, C.S. Zerefos and A.F. Bais (Eds) Springer-Verlag, Berlin, pp. 259–266. KERR, J.B. 1998. Diurnal variation of column ozone at Toronto and Edmonton. In: Atmospheric Ozone, Proceedings of XVIII Quadrennial Ozone Symposium, R.D. Bojkov and G. Visconti (Eds), Edigrafital S.p.A., Italy, pp. 53–56. KERR, J.B. 2002. New methodology for deriving total ozone and other atmospheric variables from Brewer spectrophotometer direct sun spectra. J. Geophys. Res. 107: doi:10.1029/2001JD001227.


182 / J.B. Kerr and V.E. Fioletov and W.F.J. EVANS. 1985. The automated Brewer spectrophotometer. In: Atmospheric Ozone, Proceedings of Quadrennial Ozone Symposium, C.S. Zerefos and A. Ghazi (Eds), Reidel, Hingham, Mass., pp. 396–401. KERR, J.B. and C.T. MCELROY. 1993. Evidence for large upward trends of ultraviolet-B radiation linked to ozone depletion. Science, 262: 1032–1034. KERR, J.B.; C.T. MCELROY, D.W. TARASICK and D.I. WARDLE. 1994. The Canadian Ozone Watch and UV-B advisory programs. In: Ozone in the Trophosphere and Stratosphere, Proceedings of the Quadrennial Ozone Symposium 1992. R.D. Hudson (Ed), Charlottesville, VA, NASA Conference Publication 3266, Springer-Verlag, Berlin, pp. 794–797. KERR, J.B.; and G. SECKMEYER (Lead Authors), A.F. BAIS, G. BERNHARD, M. KERR, J.B.; C.T. MCELROY, D.I. WARDLE, R.A. OLAFSON

BLUMTHALER, S.B. DIAZ, N. KROTKOV, D. LUBIN, R.L. MCKENZIE, A.A. SABZIPARVAR and J. VERDEBOUT. 2003. Surface Ultraviolet Radiation: Past and Future. In: Scientific Assessment of Ozone Depletion: 2002. Global Ozone Research and Monitoring Project – Report No. 47, Chapter 5, World Meteorological Organization, Geneva, 46 pp. KERR, J.B. and J.M. DAVIS. 2007. New methodology applied to deriving total ozone and other atmospheric variables from global irradiance spectra. J. Geophys. Res. 112: 021301, doi:10.1029/2007JD008708. KIEDRON, P.W.; L.H. HARRISON, J.L. BERNDT, J.J. MICHALSKY and A.F. BEAUBIEN. 2001. Specifications and performance of UV rotating shadowband spectroradiometers (UV-RSS). In: Proc. Ultraviolet Ground- and Space-based Measurements, Models, and Effects, 29 July–3 August 2001, SPIE, pp. 249–258. KIRCHHOFF, V.W.J.H.; A.A. SILVA, C.A. COSTA, N. PAES LEME, H.G. PAVAO and F. ZARATTI. 2001. UV-B optical thickness observations of the atmosphere. J. Geophys, Res. 106: 2963–2973. KÖPKE, P.; D. ANDWENDER, M. MECH, A. OPPENRIEDER, J. REUDER, A.

and J. SCHWEEN. 2005. Actual state of the UV radiation transfer model package STAR. In: Current Problems in Atmospheric Radiation, Proc. International Radiation Symposium, 23–28 August 2004, Busan, Korea, pp. 71–74. RUGGABER, M. SCHREIER, H. SCHWANDER

KORONAKIS, P.S.; G.K. SFANTOS, A.G. PALIATSOS, J.K. KALDELLIS, J.E. GAROFALAKIS and I.P. KORONAKI. 2002. Interrelations of UV-global/global/diffuse solar irradiance components and UV-global attenuation on air pollution episode days in Athens, Greece. Atmos. Environ. 36: 3173–3181. KROTKOV, N.A.; P.K. BHARTIA, J.R. HERMAN, V. FIOLETOV and J. KERR. 1998. Satellite estimation of spectral surface UV irradiance in the presence of tropospheric aerosols, 1, Cloud-free case. J. Geophys. Res. 103: 8779–8793. KROTKOV, N.A.; J.R. HERMAN, P.K BHARTIA, V. FIOLETOV and Z. AHMAD. 2001. Satellite estimation of spectral UV irradiance, 2, Effects of homogeneous clouds and snow. J. Geophys. Res. 106: 11743–11759. KROTKOV, N.; J. HERMAN, P.K. BHARTIA, C. SEFTOR, A. AROLA, J. KAUROLA, S. KALLISKOTA, P. TAALAS and I.V. GEORDZHAEV. 2002. Versiio 2 Total Ozone Mapping Spectrometer ultraviolet algorithm: Problems and enhancements. Opt. Eng. 41: 3028–3039. KROTKOV, N.A.; P.K. BHARTIA, J.R. HERMAN, J.R. SLUSSER, G.J. LABOW, G.R. SCOTT, G.T. JANSON, T. ECK and B.N. HOLBEN. 2005a. Aerosol ultraviolet absorption experiment (2002 to 2004), part 1: ultraviolet multifilter rotating shadowband radiometer calibration and intercomparison with CIMEL sunphotometers. Opt. Eng. 44: 1–17. KROTKOV, N.A.; P.K. BHARTIA, J.R. HERMAN, J.R. SLUSSER, G.R. SCOTT, G.J. LABOW, A.P. VASILKOV, T. ECK, O. DOUBOVIK and B.N. HOLBEN. 2005b. Aerosol ultraviolet absorption experiment (2002 to 2004), part 2: absorption optical thickness, refractive index, and single scattering albedo. Opt. Eng. 44: 18–34. KRUEGER, A.J.; L.S. WALTER, P.K. BHARTIA, C.C. SCHNETZLER, N.A. KROTKOV,

and G.J.S. BLUTH. 1995. Volcanic sulfur dioxide measurements from the total ozone mapping spectrometer instruments. J. Geophys. Res. 100: 14057–14076. ´ KRZYSCIN, J.W. 1996. UV controlling factors and trends derived from groundbased measurements taken at Belsk, Poland, 1976-1994. J. Geophys. Res. 101: 16797–16805. ´ KRZYSCIN, J.W.; K. EERME and M. JANOUCH. 2004. Long-term variations of the UV-B radiation over central Europe derived from reconstructed UV time series. Ann. Geophys. 22, 1473–1485. I. SPROD

KYLLING, A.; A.R. WEBB, A.F. BAIS, M. BLUMTHALER, R. SCHMITT, S. THIEL, A. KAZANTZIDIS, R. KIFT, M. MISSLBECK, B. SCALLHART, J. SCHREDER, C. TOPALOGLOU, S. KAZADZIS and J. RIMMER. 2003. Actinic flux determination from measurements of irradiance. J. Geophys. Res. 108: 4506, doi:10.1029/2003JD003236. KYLLING, A.; A.R. WEBB, R. KIFT, G.P. GOBBI, L. AMMANNATO, F. BARNABA, A. BAIS, S. KAZADZIS, M. WENDISCH, E. JÄKEL, S. SCHMIDT, A. KNIFFKA, S. THIEL, W. JUNKERMANN, M. BLUMTHALER, R. SOLBERNAGEL, B. SCHALL-

and B. Spectral actinic flux in the lower troposphere: measurement and 3-D simulations for cloudless, broken cloud and overcast situations. Atmos. Chem. Phys. 5: 1975–1997. LAKKALA, K.; E. KYRO and T. TURUNEN. 2003. Spectral UV measurements at Sodankylä during 1990–2001. J. Geophys. Res. 108: 45621, doi:10.1029/2002JD003300. HART, R. SCHMITT, B. KJELDSTAD, T.M. THORSETH, R. SCHEIRER

MAYER. 2005.

LANGFORD, A.O.; R. SCHOFIELD, J.S. DANIEL, R.W. PORTMANN, M.L. MCIAMED, H.L. MILLER, E.G. DUTTON and S. SOLOMON. 2007. On the variability of the Ring effect in the near ultraviolet: understanding the role of aerosols and multiple scattering. Atmos. Chem. Phys. 7: 575–586. LANTZ, K.O.; P. DISTERHOFT, J.J. DELUISI, E. EARLY, A. THOMPSON, D. BIGELOW

and J. SLUSSER. 1999. Methodology for deriving clear-sky erythemal calibration factors for UV broadband radiometers of the US Central Calibration Facility. J. Atmos. Oceanic Technol. 16: 1736–1752. LAPETA, B.; O. ENGELSON, Z. LITYNSKA, B. KOIS and A. KYLLING. 2000. Sensitivity of surface UV radiation and ozone column retrieval to ozone and temperature profile. J. Geophys, Res. 105: 5001–5007. LEMUS-DESCHAMPS, L.; L. RIKUS and P. GIES. 1999. The operational Australian ultraviolet index forecast 1997. Meteorol. Appl. 6: 241–251. LENOBLE, J.; T. MARTIN, M. BLUMTHALER, R. PHILIPONA, A. ALBOLD, T. CABOT, A. DE LA CASINIÈRE, J. GRÖBNER, D. MASSEROT, M. MÜLLER, T. PICHLER, G. SECKMEYER, D. SCHMUCKI, M.L. TOURÉ and A. YVON. 2002. Retrieval of the ultraviolet aerosol optical depth during a spring campaign in the Bavarian Alps. Appl. Opt. 41: 1629–1639. LENOBLE, J.; A. KYLLING and I. SMOLSKAIA. 2004. Impact of snow cover and topography on ultraviolet irradiance at the Alpine station of Briancon. J. Geophys. Res. 109: D08107, doi:10.1029/2004JD004523. LEVELT, P.F.; E. HILSENRATH, G.W. LIPPELMEIER, G.H.J.VAN DER OORD, P.K. BHARTIA, J. TAMMINEN, J.F.DE HAAN and J.P. VEEFKIND. 2006. Science objectives of the ozone monitoring instrument. IEEE Trans. Geosci. Rem. Sens. 44: 1199–1208. LINDFORS, A. and L. VUILLEURMIER. 2005. Erythemal UV at Davos (Switzerland), 1926-2003, estimated using total ozone, sunshine duration, and snow depth. J. Geophys. Res. 110: doi:10.1029/2004JD005231. LONG, C.S.; A.J. MILLER, H.-T. LEE, J.D. WILD, R.C. PRZYWARTY and D. HUFFORD. 1996. Ultraviolet Index forecasts issued by the National Weather Service. Bull. Am. Meteorol. Soc. 77: 729–748. MADRONICH, S. 1994. Increases in biologically damaging UV-B radiation due to stratospheric ozone depletion: A brief review. Arch. Hydrobiol. 43: 17–30. MADRONICH, S. and F.R. DE GRUIJL. 1994. Stratospheric ozone depletion between 1979 and 1992: Implication for biologically active ultraviolet-B radiation and non-melanoma skin cancer incidence. Photochem. Photobiol. 59: 541–546. MADRONICH, S. and S. FLOCKE. 1997. Theoretical estimation of biologically effective UV radiation at the earth’s surface. In: NATO ASI Series, Vol. 52, C.S. Zerefos and A.F. Bais (Eds), Springer-Verlag, Berlin, pp. 23–48. MARSHAK, A. and A.B. DAVIS. 2005. 3D radiative transfer in cloudy atmospheres, Springer-Verlag, Berlin, 686 pp. MAYER, B. and A. KYLLING. 2005. Technical note: The libRadtran software package for radiative transfer calculations – description and examples of use. Atmos. Chem. Phys. 5: 1855-1877. MCARTHUR, L.J.B.; V.E. FIOLETOV, J.B. KERR, C.T. MCELROY and D.I. WARDLE. 1999. Derivation of UV-A irradiance from pyranometer measurements. J. Geophys. Res. 104: 30139–30151. MCELROY, C.T. 1995. A spectroradiometer for the measurement of direct and scattered solar irradiance from on-board the NASA ER-2 high-altitude research aircraft. Geophys. Res. Lett. 22: 1361–1364.


Surface Ultraviolet Radiation / 183 and P.V. JOHNSTON. 1991. The relationship between erythemal UV and ozone derived from spectral irradiance measurements. Geophys. Res. Lett. 18: 2269–2272. MCKENZIE, R.L.; B. CONNOR and G. BODEKER. 1999. Increased summertime UV radiation in New Zealand in response to ozone loss. Science, 285: 1709–1711. MCKENZIE, R.L.; P.V. JOHNSTON, D. SMALE, B.A. BODHAINE and S. MADRONICH. 2001a. Altitude effects on UV spectral irradiance deduced from measurements at Lauder, New Zealand and at Mauna Loa Observatory, Hawaii. J. Geophys. Res. 106: 22845–22860. MCKENZIE, R.L.; G. SECKMEYER, A.F. BAIS, J.B. KERR and S. MADRONICH. 2001b. Satellite retrievals of erythemal UV dose compared with groundbased measurements at northern and southern midlatitudes. J. Geophys. Res. 106: 24051–24062. MCKINLAY, A.F. and B.L. DIFFEY. 1987. A reference action spectrum for ultraviolet induced erythemal in human skin. In: Human Exposure to Ultraviolet Radiation: Risks and Regulations. W.R. Passchier and B.M.F. Bosnajakovich (Eds), Elsevier, Amsterdam , pp. 83–87. MIKKELBORG, O.; G. SAXEBOL and B. JOHNSEN. 2000. Ultraviolet monitoring in Norway on the web. Radiat. Prot. Dosim. 91: 165–167. MIN, Q. and L.C. HARRISON. 1998. Synthetic spectra for terrestrial ultraviolet from discrete measurements. J. Geophys. Res. 103: 17033–17039. MIN, Q.L.; L.C. HARRISON, P. KIEDRON, J. BERNDT and E. JOSEPH. 2004. A highresolution oxygen A-band and water vapor band spectrometer. J. Geophys. Res. 109: D02202, doi:10.1029/2003JD003540. MONKS, P.S.; A.R. RICKARD, S.L. HALL and N.A.D. RICHARDS. 2004. Attenuation of spectral actinic flux and photolysis frequencies at the surface through homogenous cloud fields. J. Geophys. Res. 109: D17206, doi:10.1029/ 2003JD004076. NECKEL, H. and D. LABS. 1984. The solar radiation between 3300 Å and 12500 Å. Sol. Phys. 90: 205–258. NOXON, J. 1975. Nitrogen dioxide in the stratosphere and troposphere measured by ground based absorption spectroscopy. Science, 189: 547–549. PARISI, A.V.; J. SABBURG, M.G. KIMLIN and N. DOWNS. 2003. Measured and modeled contributions to UV exposures by the albedo of surfaces in an urban environment. Theor. Appl. Climatol. 76: 181–188. PEETERS, P.; J.-F. MÜLLER, P.C. SIMON, E. CELARIER and J. HERMAN. 1998. Estimation of UV flux at the Earth’s surface using GOME data. ESA Earth Observ. Quart. 58: 39–40. PETTERS, J.L.; V.K. SAXENA, J.R. SLUSSER, B.N. WENNY and S. MADRONICH. 2003. Aerosol single scattering albedo retrieved from measurements of surface irradiance and a radiative transfer model. J. Geophys. Res. 108: doi:10.1029/2002JD002360. PFEIFER, M.T.; P. KOEPKE and J. REUDER. 2006. Effects of altitude and aerosol on UV radiation. J. Geophys. Res. 111: D01203, doi:10.1029/ 2005JD006444. PFISTER, G.; R.L. MCKENZIE, J.B. LILEY, A. THOMAS, B.W. FORGAN and C.N. LONG. 2003. Cloud coverage based on all-sky imaging and its impact on surface solar irradiance. J. Appl. Meteorol. 42: 1421–1434. QIN, Y.; M.A. BOX and D.L.B. JUPP. 2002. Inversion of multiangle sky radiance measurements for the retrieval of atmospheric optical properties – 1. Algorithm. J. Geophys. Res. 107: doi:10.1029/2001JD000945. RICCHIAZZI, P.; S. YANG, C. GAUTIER and D. SOWLE. 1998. SBDART: a research and teaching software tool for plane-parallel radiative transfer in the Earth’s atmosphere. Bull. Am. Meteorol. Soc. 79: 2101–2114. RICCHIAZZI, P. and C. GAUTIER. 1998. Investigation of the effect of surface heterogeneity and topography on the radiation environment of Palmer Station, Antarctic, with a hybrid three-dimensional radiative transfer model. J. Geophys. Res. 103: 6161–6176. ROZEMA, J.; B. VAN GEEL, L.O. BJÖRN, J. LEAN and S. MADRONICH. 2002. Toward solving the UV puzzle. Science, 296: 1621–1622. SABBURG, J. and J. WONG. 2000. The effect of clouds on enhancing UVB irradiance at the Earth’s surface: A one year study. Geophys. Res. Lett. 27: 3337–3340. SABZIPARVAR, A.A.; K.P. SHINE and P.M. de FORSTER. 1999. A model-derived global climatology of UV irradiance at the Earth’s surface. Photochem. Photobiol. 69: 193–202. MCKENZIE, R.L.; W.A. MATTHEWS

SCHMUCKI, D.A. and R. PHILIPONA. 2002. Ultraviolet radiation in the Alps: the

altitude effect. Opt. Eng. 41: 3090–3095. and G. SECKMEYER. 2002. Modifications of spectral UV irradiance by clouds. J. Geophys. Res. 107: 4296, doi:10.1029/2001JD001297. SCOTTO, J.; G. COTTON, F. URBACH, D. BERGER and T. FEARS. 1988. Biologically effective ultraviolet radiation: surface measurements in the U.S. Science, 239: 762–764. SECKMEYER, G.; R. ERB and A. ALBOLD. 1996a. Transmittance of a cloud is wavelength-dependent in the UV-range. Geophys. Res. Lett. 23: 2753–2755. SECKMEYER, G.; G. BERNHARD, B. MAYER and R. ERB. 1996b. High accuracy spectroradiometry of solar UV radiation. Metrologia, 32: 697–700. SCHWANDER, H.; P. KOEPKE, A. KAIFEL

SECKMEYER, G.; A. BAIS, G. BERNHARD, M. BLUMTHALER, C.R. BOOTH, K. LANTZ and R.L. MCKENZIE. 2005. Instruments to measure solar ultraviolet irradiance, Part 2: Broadband instruments measuring erythemally weighted solar irradiance. World Meteorological Organization. WMO TD No. 1302, 54 pp. SETLOW, R.B. 1974. The wavelengths in sunlight effective in producing skin cancer: a theoretical analysis. Proc. Nat. Acad. Sci. USA, 71: 3363–3366. STAMNES, K. 2002. Ultraviolet and visible radiation in the atmosphere-ocean system: a tutorial review of modeling capabilities. Opt. Eng. 41: 3008–3018. TAALAS, P.; J. KAUROLA, A. KYLLING, D. SHINDELL, R. SAUSEN, M. DAMERIS, V.

and B. STEIL. 2000. The impact of greenhouse gases and halogenated species on future solar UV radiation doses. Geophys. Res. Lett. 27: 1127–1130. TANSKANEN, A.; N.A. KROTKOV, J.R. HERMAN and A. AROLA. 2006. Surface ultraviolet irradiance from OMI. IEEE Trans. Geosci. Rem. Sens. 44: 1267–1271. TARASICK, D.W.; V.E. FIOLETOV, D.I. WARDLE, J.B. KERR, L.J.B. MCARTHUR and C.A. MCLINDEN. 2003. Climatology and trends of surface UV radiation. ATMOSPHERE-OCEAN, 41: 121–138. GREWE, J. HERMAN, J. DAMSKI

THUILLIER,G.; L. FLOYD, T.N. WOODS, R. CEBULA, E. HILSENRATH, M. HERSÉ

and D. LABS. 2004. Solar irradiance reference spectra for two solar active levels. Adv. Space Res. 34: 256–261. TOPALOGLOU, C.; S. KAZADZIS, A.F. BAIS, M. BLUMTHALER, B. SCHALLHART

and D. BALIS. 2005. NO2 and HCHO photolysis frequencies from irradiance measurements in Thessoloniki, Greece. Atmos. Chem. Phys. 5: 1645–1653. UNEP. 2006. Environmental effects of ozone depletion and its interactions with climate change: 2006 assessment, UNEP (United Nations Environment Programme) Report, 209 pp. VAN WEELE, M.; T.J. MARTIN, M. BLUMTHALER, C. BROGNIEZ, P.N. DEN OUTER, O. ENGELSEN, J. LENOBLE, B. MAYER, G. PFISTER, A. RUGGABER, B. WALRAVENS, P. WEIHS, B.G. GARDINER, D. GILLOTAY, D. HAFERL, A. KYLLING, G. SECKMEYER and W.M.F. WAUBEN. 2000. From model intercomparison toward benchmark UV spectra for six real atmospheric cases. J. Geophys. Res. 105: 4915–4925. VASILKOV, A.P.; J. HERMAN, N.A. KROTKOV, M. KAHRU, B.G. MITCHELL and C. HSU. 2002. Problems in assessment of the ultraviolet penetration into natural waters from space-based measurements. Opt. Eng. 41: 3019–3027. VERDEBOUT, J. 2000. A method to generate surface UV radiation maps over Europe using GOME, Meteosat, and ancillary geophysical data. J. Geophys. Res. 105: 5049–5058. VERDEBOUT, J. 2004. A satellite-derived UV radiation climatology over Europe to support impact studies. Arct. Antarct. Alp. Res. 36: 357–363. WANG, P.; A. RICHTER, M. BRUNS, J.P. BURROWS, W. JUNKERMANN, K.-P. HEUE, T. WAGNEW, U. PLATT and I. PUNDT. 2005a. Airborne multi-axis DOAS measurements of tropospheric SO2 plumes in the Po-valley, Italy. Atmos.Chem. Phys. Disc. 5: 2017–2045. WANG, P.; A. RICHTER, M. BRUNS, V.V. ROSANOV, J.P. BURROWS, K.-P. HEUE, T. WAGNER, I. PUNDT and U. PLATT. 2005b. Measurements of tropospheric NO2 with an airborne multi-axis DOAS instrument. Atmos.Chem. Phys. 5: 337–343. WARDLE, D.I.; J.B. KERR, C.T. MCELROY and D.R. FRANSIS. 1997. Ozone science: A Canadian perspective on the changing ozone layer, Report CARD 97-3, Environment Canada, 119 pp.


184 / J.B. Kerr and V.E. Fioletov WEATHERHEAD, E.C.; G.C. TAIO, G.C. REINSEL, J.E. FREDERICK, J.J. DELUISI, D.

WENDISCH, M.; P. PILEWSKIE, E. JAKEL, S. SCHMIDT, J. POMMIER, S. HOWARD,

and W.-K. TAM. 1997. Analysis of long-term behavior of ultraviolet radiation measured by Robertson-Berger meters at 14 sites in the United States. J. Geophys. Res. 102: 8737–8754.

H.H. JONSSON, H. GUAN, M. SCHRODER and B. MAYER. 2004. Airborne measurements of areal spectral albedo over different sea and land surfaces. J. Geophys. Res. 109: doi:10.1029/2003JD004392. WUTTKE, S. and G. SECKMEYER. 2006. Spectral radiance and sky luminance in Antarctica: a case study. Theor. Appl. Climatol. 85: doi:10.1029/s00704005-0188-2. YLIANTTILA, L. and J. SCHREDER. 2005. Temperature effects of PTFE diffusers. Opt. Mater. 27: 1811–1814. YOUNG, A.R. and S.L. WALKER. 2005. UV radiation, Vitamin D and human health: an unfolding controversy introduction. Photochem. Photobiol. 81: 1243–1245. ZARATTI, F.; R.N. FORNO, J.G. FUENTES and M.F. ANDRADE. 2003. Erythemally weighted UV variations at two high-altitude locations. J. Geophys. Res. 108: 4623. ZEREFOS, C.; C. MELETI, D. BALIS, K. TOURALI and A.F. BAIS. 1998. Quasi-biennial and longer-term changes in clear sky UV-B solar irradiance. Geophys, Res. Lett. 25: 4345–4348.

CHOI

WEATHERHEAD, E.C.; G.C. REINSEL, G.C. TIAO, X.-L. MENG, D. CHOI, W.-K. CHEANG, T. KELLER, J. DELUISI, D.J. WUEBBLES, J.B. KERR, A.J. MILLER, S.J. OLTMANS and J.E. FREDERICK. 1998. Factors affecting the detection of trends: Statistical considerations and applications to environmental data. J. Geophys. Res. 103: 17149–17161. WEATHERHEAD, E.; D. THEISEN, A. STEVERMER, J. ENAGONIO, B. RABINOVITCH,

and 2001. Temperature dependence of the Brewer ultraviolet data. J. Geophys. Res. 106: 34121–34129. WEBB, A.R.; R. KIFT, S. THIEL and M. BLUMTHALER. 2002. An empirical method for the conversion of spectral UV irradiance measurements to actinic flux data. Atmos. Environ. 36: 4397–4404. WEBB, A.R.; A. KYLLING, M. WENDISCH and E. JAKEL. 2004. Airborne measurements of ground and cloud spectral albedos under low aerosol loads. J. Geophys. Res. 109: doi:10.1029/2004JD004768. P DISTERHOFT, K. LANTZ, R. MELTZER, J. SABBURG, J. DELUISI, J. RIVES

J. SHREFFLER.
