Search

A method is presented that combines individual ground based ultraviolet (UV) measurements and satellite data from MSG (Meteosat Second Generation) to generate a UV-Index map all over the region of Austria. Cloud modification factors (CMFs) gathered from satellite images give an area wide information of the cloud situation but compared to ground based measurements significant discrepancies have been found. These discrepancies are especially large for high mountain stations but also for low altitude sites differences between satellite derived and ground based data in the order of 15% have been found. To overcome these discrepancies a correction procedure based on the correlation of both data sets at the pixel of the measurement stations is developed. The uncertainty of the final UV-Index map is evaluated exemplarily for the pixel of the measurement sites Bad Vöslau and München by eliminating the information of both sites from the UV-Index map generation process and comparing afterwards calculated and measured results. More than 5000 maps for all weather conditions have been evaluated leading to a mean agreement of 1.02 (standard deviation ±0.31, Bad Vöslau) and 1.01 (standard deviation ±0.34, München) between calculated and measured UV-Indexes. [ABSTRACT FROM AUTHOR]

A bi-lateral intercomparison of erythemal broadband radiometers was performed between seven UV calibration facilities. The calibrations provided by the instruments owners were compared relative to the characterisation and calibration performed at PMOD/WRC in Davos, Switzerland. The calibration consisted in the determination of the spectral and angular response of the radiometer, followed by an absolute calibration performed outdoors relative to a spectroradiometer which provided the absolute reference. The characterization of the detectors in the respective laboratories are in good agreement: The determinations of the angular responses have deviations below ±4% and the spectral responses agree within ±20%. A "blind" intercomparison of the erythemally weighted irradiances derived by the respective institutes and PMOD/WRC showed consistent measurements to within ±2% for the majority of institutes. One institute showed slightly larger deviation of 10%. The differences found between the different instrument calibrations are all within the combined uncertainty of the calibration. [ABSTRACT FROM AUTHOR]

Results are presented from the Actinic Flux Determination from Measurements of Irradiance (ADMIRA) campaign to measure spectral global UV irradiance and actinic flux at the ground, beneath an atmosphere well defined by supporting measurements. Actinic flux is required to calculate photolysis rates for atmospheric chemistry, yet most spectral UV measurements are of irradiance. This work represents the first part of a project to provide algorithms for converting irradiances to actinic fluxes with specified uncertainties. The campaign took place in northern Greece in August 2000 and provided an intercomparison of UV spectroradiometers measuring different radiation parameters, as well as a comprehensive radiation and atmospheric dataset. The independently calibrated spectroradiometers measuring irradiance and actinic flux agreed to within 5%, while measurements of spectral direct irradiance differed by 9%. Relative agreement for all parameters proved to be very stable during the campaign. A polarization problem in the Brewer spectrophotometer was identified as a problem in making radiance distribution measurements with this instrument. At UV wavelengths actinic fluxes F were always greater than the corresponding irradiance E by a factor between 1.4 and 2.6. The value of the ratio F : E depended on wavelength, solar zenith angle, and the optical properties of the atmosphere. Both the wavelength and solar zenith angle dependency of the ratio decreased when the scattering in the atmosphere increased and the direct beam proportion of global irradiance decreased, as expected. Two contrasting days, one clear and one with higher aerosol and some cloud, are compared to illustrate behavior of the F : E ratio. [ABSTRACT FROM AUTHOR]

To study the value of the Austrian Academic Computer Network ACOnet for teleradiology, 1740 test image data-sets and 620 image data-sets were exchanged between the departments of diagnostic radiology of the Universities of Innsbruck and Graz using the ACOnet service. Data transmission was reliable and fast with an average transfer capacity of 170 kByte s range 94-341 . During the test phase, no major problems with image transfer occurred. Assuming that problems like security of patient data-sets, data compression and data verification can be solved, the ACOnet service would be a useful additional tool for telemedicine applications throughout Austria and eastern Europe. [ABSTRACT FROM AUTHOR]