In this study we have analysed the sensitivity of the erythemally effective radiation to uncertainties in measured total ozone content of the atmosphere (TOC).These uncertainties result from a restricted spatial resolution, a restricted temporal resolution or the restricted accuracy of measured TOC. Daily operational total ozone measurements from different instruments made over several years were applied. Measurements were gained space born by EPTOMS, ERS-2/GOME and TOVS and from the ground by Dobson and Brewer Spectrophotometers for the locations of Hradec Kralove (Czech Republic, 50°N), Nairobi (Kenya, 1°S) and Springbok (Rep. of South Africa, 30°S). The measurement uncertainties were analyzed by an inter-comparison of modeled erythemally effective UV radiation when using different sources of TOC. The evaluation of the uncertainties due to temporal delays was done in using TOC values with different temporal shifts. The influence of spatial gaps in TOC measurements was estimated separately in longitude and latitude up to distances of 1000 km around the measuring sites. From this analysis, requirements on the spatial resolution, temporal resolution and measuring uncertainties of total ozone measurements to calculate the erythemally effective UV radiation with a pre-selected accuracy can be derived in dependence of location and season.
There has been a growing interest in the connection of vitamin D and solar ultraviolet-B (UVB) radiation because numerous studies have shown that there is an anti-correlation between the vitamin D level and many types of cancer and various diseases. Additionally there is the well known anti-correlation with osteoporosis and its progress, a disease that affects approximately in 30% of all post-menopausal women. Information about the actual effectiveness of solar UVB radiation in producing vitamin D could therefore a very helpful tool for health care. Such information should base on well estimated parameters either measured or modeled. Therefore, we investigated the possibilities in measuring, modeling and forecasting the vitamin D effective radiation. Measurements were made with two different broadband devices. One is a hand-held radiometer which was designed as a personal dosimeter and another is a device which is in use world wide to measure the erythemally effective UV radiation. Further on we introduce a world wide forecast of the vitamin D effective UV radiation for clear skies together with its validation. Input parameters for the forecast are date and time, geographical position and altitude, total ozone, low aerosol content and neglected albedo.
The objectives of the COST action 726 are to establish long-term changes of UV-radiation in the past, which can only be derived by modelling with good and available proxy data. To find the best available models and input data, 16 models have been tested by modelling daily doses for two years of data measured at four stations distributed over Europe. The modelled data have been compared with the measured data, using different statistical methods. Models that use Cloud Modification Factors for the UV spectral range, derived from co-located measured global irradiance, give the best results.
The determination of UV- and light doses received by people as a function of their activities and their environment, for present and future conditions, is the aim of the presented study. In this paper we present first preliminary results. Measurements of the total daily UV dose received by horizontal and vertical parts of the human body were performed on three chosen days in the region of Vienna, Austria. The measurements were performed in the UV and in the visible spectral range using ultraviolet selective sensors and sensors adapted to human eye sensitivity. Data acquisition was performed by using dataloggers. In this way it was also possible to determine the UV intensity and dose as a function of time and location. The UV intensity was determined for typical outdoor and indoor activities such as walking in a street, in a forest or in flat unobstructed areas. Indoors the determination of UV doses is more straightforward, the determination of the visible dose is however much more complex. A software was developed to determine the total daily dose received by the human body as a function of day and occupation.
Since October 1995 a global daily forecast of the UV index and the daily dose, as the irradiance of the biologically effective ultraviolet radiation, for clear sky is calculated. The Austrian model as well as the input parameters are described. By connecting the daily dose with the sensitivity of the photobiological skin types, a recommendation is given to select an appropriate sun protection factor of a sunscreen to avoid overexposure of the skin. The validation of the Austrian forecast model is done by long-term measurements of the biologically effective ultraviolet radiation. Measurements were taken from 6 different sites at 4 continents (Antarctica, Australia, America and Europe) covering the latitudinal range from 67 degree(s)N to 60 degree(s)S. By using the underestimation as criteria in the sense of radiation protection, the Austrian model shows less than 12% underestimation over the whole period for the UV index and less than 10% for the daily dose. The evaluation shows further that the forecast of the daily dose is much more influenced by the attenuation due to clouds than the UV index.
Beside the sun elevation angle, the total ozone content (TOC) of the atmosphere is a main input parameter of models to predict the biologically-effective UV radiation. Therefor TOC was analysed for the domain of Central Europe. The data domain contains the area from 7 degree(s)E to 17 degree(s)E in longitude and from 45 degree(s) to 50 degree(s) in latitude. Ground based as well as satellite based measurements from EPTOMS were involved. The temporal and spatial variability of TOC was analysed using auto-correlation and fitting auto- correlation functions. It becomes evident that temporal correlation decrease rapidly within the first 9 days down to the level of 1/e. From spatial correlation functions de- correlation distances (1/e) are estimated with 180 km E-W and 145 km for S-N direction. The analysis of TOC variability per 100 km for the domain of Austria was also examined. The results show that the highest values can reach up to 18%/100 km. Day-to-day variability for a certain location may exceed this level by a few percent (25%/day). These results show that for the calculation of the biologically effective UV radiation a high spatial resolution of TOC data is necessary to ensure an appropriate quality.
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