SEASONAL VARIATION OF SOLAR UV-RADIATION AT A HIGH MOUNTAIN STATION

Abstract— At the high mountain station Jungfraujoch (3576 m), the maximum daily totals for erythemal dose (G_ER), UV-A radiation (G_UVA) and global radiation (G) are 29 Sunburn Units d⁻¹, l.7 MJ m⁻²d⁻¹ and 37 MJ m⁻² d⁻¹. The maximum instantaneous values at solar noon in midsummer are 4.2 Sunburn Unit h⁻¹, 53 W m⁻² and 1110 W m⁻². A significantly nonlinear relation between G_ER and G results from the influence of the irradiated ozone mass on the UV-B erythemal dose. In contrast, G_UVA and G are linearly proportional, which can be seen from the diurnal and seasonal courses of the ratios G_ER/G and G_UVA/G AND from their dependence on the optical air mass. UV-A radiation flux is less attenuated by cloudiness than is global radiation. This effect is masked for the erythemal dose by variations in the ozone concentration. Due to seasonal ozone layer thickness and effective pathlength variations, the ratio G_ER/G shows a significant asymmetry. At the autumn equinox it is about 16% higher than at the spring equinox.     

ERYTHEMAL UV-B IRRADIANCE (ROBERTSON-BERGER SUNBURN METER DATA) UNDER OZONE DEFICIENCIES IN WINTER/SPRING 1993

Abstract –Robertson-Berger sunburn meter data recorded from August 1992 to May 1993 (Innsbruck, 577 m above sea level, Austria) were compared with measurements taken in previous years. In February and March 1993 instantaneous values on clear days were found to be higher by up to 37% than those registered in previous years (1986–1988). However, in winter/spring 1993 daily totals for all days, averaged over 7 days, were within the range of standard deviation of the previous years (1981–1988). Therefore the cumulative UV-B exposure of the ecosystem is within the general range of variability even under the record low ozone values in winter/spring 1993, while single peak doses were enhanced significantly.     

OZONE AND ULTRAVIOLET-B IRRADIANCES: EXPERIMENTAL DETERMINATION OF THE RADIATION AMPLIFICATION FACTOR

Abstract— During the period 1981–1993, measurements of solar UV irradiances were made at the High-Alpine Research Station Jungfraujoch (Switzerland, 3576 m a.s.l.) to determine the radiation amplification factor (RAF) for the Robertson-Berger sunburn meter and for the narrow-band wavelength ranges of the Eppley filter spectrometer. The Robertson-Berger sunburn meter model 500 showed a RAF of 1.07 ± 0.15 at solar elevations between 20° and 60°. The RAF for human erythema is 1.1 in comparison. Therefore the Robertson-Berger sunburn meter is suitable to measure the influence of total atmospheric ozone variations on the effective erythemal irradiance. In the narrow-band wavelength ranges of the Eppley filter spectrometer the RAF increases greatly at shorter wavelengths with RAF of 1.06, 1.40 and 2.35 for the optical centers 315.1 nm, 311.1 nm and 305.2 nm, evaluated at 30° solar elevation. In order to minimize perturbations by aerosol optical depth and albedo in the evaluation of the RAF the ratios of UV irradiances to total irradiances were evaluated.     

SOLAR UVB-ALBEDO OF VARIOUS SURFACES

Abstract— Measurements of the albedo of various surfaces in open grounds show significant differences for solar UVB radiation and total solar radiation (0.3–3μm). Above grassland, that albedo for solar UVB radiation is significantly smaller than that for total solar radiation (UVB: 1.3%, total: 20.7%); contrary to that, the albedo for UVB radiation is significantly higher above new dry snow (UVB: 94.4%, total: 87.0%). Consequences resulting therefrom are being quantitatively discussed with respect to the solar radiant exposure of individuals standing outdoors. Keratitis Solaris, for example, hardly occurs in snow-free terrain, even at high solar irradiance in summer; it occurs, however, in snow-covered terrain, in spite of low solar irradiance in winter and spring.     

Combining MN6 Octahedra and PN5 Trigonal Bipyramids in the Mica-like Nitridophosphates MP6N11 (M=Al,In)

Layered silicates are a very versatile class of materials with high importance to humanity. The new nitridophosphates MP₆N₁₁ (M=Al, In), synthesized from MCl₃, P₃N₅ and NH₄N₃ in a high-pressure high-temperature reaction at 1100 °C and 8 GPa, show a mica-like layer setup and feature rare nitrogen coordination motifs. The crystal structure of AlP₆N₁₁ was elucidated from synchrotron single-crystal diffraction data (space group Cm (no. 8), a=4.9354(10), b=8.1608(16), c=9.0401(18) Å, β=98.63(3)°), enabling Rietveld refinement of isotypic InP₆N₁₁. It is built up from layers of PN₄ tetrahedra, PN₅ trigonal bipyramids and MN₆ octahedra. PN₅ trigonal bipyramids have been reported only once and MN₆ octahedra are sparsely found in the literature. AlP₆N₁₁ was further characterized by energy-dispersive X-ray (EDX), IR and NMR spectroscopy. Despite the vast amount of known layered silicates, there is no isostructural compound to MP₆N₁₁ as yet.     

Structural Influence of Lone Pairs in GeP2N4, a Germanium(II) Nitridophosphate

Owing to their widespread properties, nitridophosphates are of high interest in current research. Explorative high-pressure high-temperature investigations yielded various compounds with stoichiometry MP₂N₄ (M=Be, Ca, Sr, Ba, Mn, Cd), which are discussed as ultra-hard or luminescent materials, when doped with Eu²⁺. Herein, we report the first germanium nitridophosphate, GeP₂N₄, synthesized from Ge₃N₄ and P₃N₅ at 6 GPa and 800 °C. The structure was determined by single-crystal X-ray diffraction and further characterized by energy-dispersive X-ray spectroscopy, density functional theory calculations, IR and NMR spectroscopy. The highly condensed network of PN₄-tetrahedra shows a strong structural divergence to other MP₂N₄ compounds, which is attributed to the stereochemical influence of the lone pair of Ge²⁺. Thus, the formal exchange of alkaline earth cations with Ge²⁺ may open access to various compounds with literature-known stoichiometry, however, new structures and properties.     

UVA1 radiation (340-400 nm) interferes with the perforin-granule system of CD8hi+ cytotoxic T lymphocytes in vitro

UVA1-irradiation was introduced as an innovative and effective phototherapy of atopic dermatitis (AD) and other skin diseases. In AD, a defect of a central apoptosis inducing effector system involved in immunoregulation and immune defense, i.e., the system of perforin-granules in cytotoxic T lymphocytes (CTL), was recently reported: perforin-reduction and perforin-hyperreleasability. We now investigated UVA1-effects on the perforin-granule system in vitro. Peripheral blood CTLs were exposed in vitro to 10-100 J/cm2 UVA1 (340-400 nm), and to 30-150 mJ/cm2 UVB (280-315 nm) as a control. A time-dependent perforin-granule release was induced by phorbol 12-myristate 13-acetate (PMA) and ionomycin. This release was inhibited dose-dependently by UVA1, but not by UVB. An UVA1-dose dependent pattern of sensitive (80%) and insensitive (20%) individuals was found. The kinetics of perforin release in AD-CTLs, i.e. hyperreleasability, was normalized by 50 J/cm2 UVA1 in vitro. Sodium azide as a quencher of reactive oxygen species prevented the UVA1-mediated inhibition of perforin-granule release. Our data demonstrate for the first time a dose- and wavelength-dependent UVA1-effect in vitro on a major effector system of cytotoxic lymphocytes, the system of perforin-granules. This might contribute to the further understanding of immunomodulatory UVA1-effects in vivo.     

ERYTHEMAL UV-B IRRADIANCE (ROBERTSON-BERGER SUNBURN METER DATA) UNDER OZONE DEFICIENCIES IN WINTER/SPRING 1993

Abstract: Robertson-Berger sunburn meter data recorded from August 1992 to May 1993 (Innsbruck, 577 m above sea level, Austria) were compared with measurements taken in previous years. In February and March 1993 instantaneous values on clear days were found to be higher by up to 37% than those registered in previous years (1986–1988). However, in winter/spring 1993 daily totals for all days, averaged over 7 days, were within the range of standard deviation of the previous years (1981–1988). Therefore the cumulative UV-B exposure of the ecosystem is within the general range of variability even under the record low ozone values in winter/spring 1993, while single peak doses were enhanced significantly.     

Attenuation of Erythemal Effective Irradiance by Cloudiness at Low and High Altitude in the Alpine Region

Abstract— The transmittance of cloudiness was examined for the daily totals of global erythemal effective irradiance and global total irradiance in Innsbruck (577 m above sea level [a.s.l.], Western Austria) for the periods 1981-1988 and 1993-1994 and at Jungfraujoch (3576 m a.s.l., Switzerland) for the period 1981-1990. The influence of varying cloudiness on the daily totals of global erythemal effective irradiance is considerably greater than the influence of varying ozone. The lowest transmittance for daily totals of global erythemal effective irradiance is 9.4% in Innsbruck (577 m a.s.l.) and 23.5% at Jungfraujoch (3576 m a.s.l.); the median and the 25-75 percentile range at 10/10 cloudiness are 41.8% (28.9-56.7%) and 76.8% (63.5-86.1%), respectively. The greater transmittance of global erythemal effective irradiance at Jungfraujoch originates from smaller thickness of the cloud layer in high mountains than in valleys. Similar transmittances were obtained for the daily totals of global total irradiance (300-3000 nm) as a function of cloudiness.     

SPECTRAL MEASUREMENTS OF GLOBAL AND DIFFUSE SOLAR ULTRAVIOLET-B RADIANT EXPOSURE AND OZONE VARIATIONS

Since 1985, spectral solar UV-B radiant exposure has been measured at the High Alpine Research Station Jungfraujoch, Bernese Alps, Switzerland (3576 m). Global (sun and sky) and diffuse (sky) UV-B radiant exposure on a horizontal plane are measured simultaneously by two identical devices. The detecting system consists of a rotating filter wheel with 8 interference-filters, centered at every 5 nm between 290 and 325 nm, and a halfbandwidth of ±3 nm. The special advantage of this detector is its waterproofness, allowing operation under all weather conditions. The ratio of the intensities at 305 and 315 nm is being analyzed with regard to ozone variations; for example, the ratio is reduced by a factor of 2 because of an increase in ozone content from 250 to 350 Dobson units. The relation between ozone variations and measured spectral UV-B intensity is confirmed applying Green's radiation model.