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Spectral UV records of solar irradiance at stations over Europe, Canada, and Japan were used to study long-term trends at 307.5 nm for a 25-year period, from 1992 to 2016. Ground-based measurements of total ozone, as well as satellite measurements of the Aerosol Index, the Total Cloud Cover and the surface reflectivity were also used in order to attribute the estimated changes of the UV to the corresponding changes of these factors. The present study shows that over the Northern Hemisphere, the long-term changes in UV-B radiation reaching the Earth’s surface vary significantly over different locations, and that the main drivers of these variations are changes in aerosols and total ozone. At high latitudes, part of the observed changes may also be attributed to changes in the surface reflectivity. Over Japan, the UV-B irradiance at 307.5 nm has increased significantly by 3%/decade during the past 25 years, possibly due to the corresponding significant decrease of its absorption by aerosols. It was found that the greatest part of this increase took place before the mid-2000s. The only European station, over which UV radiation increases significantly, is that of Thessaloniki, Greece. Analysis of the clear-sky irradiance for the particular station shows increasing irradiance at 307.5 nm by 3.5%/decade during the entire period of study, with an increasing rate of change during the last decade, possibly again due to the decreasing absorption by aerosols.

Background: To enable food-based strategies for the prevention of vitamin D deficiency to be evidence-based, there is a need to develop integrated predictive models of population serum 25-hydroxyvitamin D [25(OH)D] that are responsive to both solar and dietary inputs of vitamin D. Objectives: The objectives of this work were to develop and validate an integrated mathematical model with the use of data on UVB availability, exposure, and dietary intake to predict serum 25(OH)D concentrations in a nationally representative sample of adults, and then test the models performance with the use of 3 hypothetical fortification scenarios as exemplars. Methods: Data on UVB availability and hours of sunlight in Ireland were used in a mathematical model to predict serum 25 (OH)D in Irish adults aged 18‐64 y. An equation from our dose-related vitamin D supplementation trial in adults was developed and integrated into the model, which allowed us to predict the impact of changes in dietary vitamin D to the contribution to annual serum 25(OH)D concentrations, accounting for seasonality of UVB availability. Recently published estimates of the impact of 3 vitamin D food fortification scenarios on vitamin D intake in a representative sample of Irish adults were used in the model as a test. Results: The UVB- and vitamin D intake‐serum 25(OH)D components of the integrated model were both validated with the use of independent data. The model predicted that the percentage vitamin D deficiency [serum 25(OH)D

Measurements are presented of the phase function, P11, and asymmetry parameter, g ,o f five ice clouds created in a laboratory cloud chamber. At � 7 1C, two clouds were created: one comprised entirely of solid columns, and one comprised entirely of hollow columns. Similarly at � 15 1C, two clouds were created: one consisting of solid plates and one consisting of hollow plates. At � 30 1C, only hollow particles could be created within the constraints of the experiment. The resulting cloud at � 30 1C contained short hollow columns and thick hollow plates. During the course of each experiment, the cloud properties were monitored using a Cloud Particle Imager (CPI). In addition to this, ice crystal replicas were created using formvar resin. By examining the replicas under an optical microscope, two different internal structures were identified. The internal and external facets were measured and used to create geometric particle models with realistic internal structures. Theoretical results were calculated using both Ray Tracing (RT) and Ray Tracing with Diffraction on Facets (RTDF). Experimental and theoretical results are compared to assess the impact of internal structure on P 11 and g and the applicability of RT and RTDF for hollow columns. & 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

This paper presents an implementation of digital image processing tools, in order to reconstruct building geometries and urban sky view factors for individual street canyons around the world. By using the Google Street View image database, it is possible to reconstruct canyon fisheye images at any point where a Google panorama is available. The Hugin software allows the geometrically correct merging of independent images in order to create a fisheye projection, covering the upper hemispheric view of the sky. Sky view factor calculations may then be performed by specialised software on the reconstructed fisheye image. In order to analyse the fitness of reconstructed panoramas, control images taken with a fisheye lens camera were used for comparison. The Rayman model was then used to calculate total shortwave global irradiances from the restricted canyon view and from a full hemispheric view. Finally, total shortwave global irradiances were measured for the same position in the street canyon and compared against observatory measurements under a full sky view, this in order to evaluate the performance and usefulness of idealised calculations. The reconstructed urban geometries returned acceptable fine-scale descriptions, and their potential utility for scientific purposes in the atmospheric sciences was demonstrated with the examples provided.

BACKGROUND: The cutaneous synthesis of vitamin D is dependent on UVB from sunlight, but melanin reduces the penetration of UVB and thus contributes to vitamin D insufficiency in individuals with darker skin. The national guidance provided on amounts of sunlight exposure in the United Kingdom is for the light-skinned population, and in the absence of dedicated information, darker-skinned people may attempt to follow this guidance. OBJECTIVES: We determined the relative effect of a simulation of UK recommendations of summer sunlight exposure on the vitamin D status of individuals of South Asian ethnicity compared with that of whites. DESIGN: In a prospective cohort study, simulated summer sunlight exposures were provided under rigorous dosimetric conditions to 15 adults (aged 20-60 y) of South Asian ethnicity, and serum 25-hydroxyvitamin D [25(OH)D] was measured weekly. Dietary vitamin D intake was estimated. Outcomes were compared with those of 109 whites (aged 20-60 y) treated with the identical UV-radiation exposure protocol. RESULTS: At baseline (winter trough), all South Asians were vitamin D-insufficient [25(OH)D concentrations

Light is defined as that part of the electromagnetic spectrum (∼380–780 nm) that gives rise to a visual sensation. Lighting in buildings, whether through use of daylight or by artificial means, is designed primarily for the visual needs of the occupants and their expected tasks within a given space. However, solar radiation, and, depending on spectral output of the source, artificial radiation, has other effects on human physiology and behaviour. Blue light affects the circadian rhythm, mood and behaviour; at shorter wavelengths in the ultraviolet (UV) the detriments of photoaging and sunburn are balanced by the benefits of Vitamin D synthesis.

Measuring ultraviolet (UV) radiation is an intrinsic part of undertaking an UV effect study, but the science of UV measurement is not usually the main interest of the plant scientist. Nonetheless, if the UV measurement is not carefully calibrated and characterized then the trial results may be misleading, or unrealistic in terms of what might be expected from ozone depletion. This paper discusses the various methods of measuring UV radiation, and their applicability for field and forest research.

Routinely monitored radiation parameters, including those at UV wavelengths, most commonly refer to irradiance, that is the radiation incident on a flat horizontal plate. However, in the study of atmospheric chemistry, where UV radiation is a prime photochemical driver, the target molecules are approximately spherical and the actinic flux (radiation on the surface of a sphere) is a better measure of the effective radiation. Unfortunately actinic flux measurements (also known as scalar irradiance) are uncommon research measurements. The ability to convert irradiance data to actinic flux data within a reasonable degree of uncertainty would provide an actinic flux database mapped from existing irradiance databases, thus vastly increasing knowledge of actinic flux variability and climatology. Synchronised spectral UV irradiance and actinic flux measurements have been made during the ADMIRA project, and used to develop an empirical method for converting irradiance to actinic flux. With some prior knowledge of the sky conditions during the irradiance measurements the actinic flux can be estimated to within a few percent. If no knowledge of the sky conditions is available then the empirical method still returns actinic fluxes within 10% of those measured at the site for which the conversion was developed.