Atmospheric Chemistry and Physics Discussions
www.atmos-chem-phys-discuss.net
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8
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2008
10.5194/acpd-8-2143-2008
http://www.atmos-chem-phys-discuss.net/8/2143/2008/
http://www.atmos-chem-phys-discuss.net/8/2143/2008/acpd-8-2143-2008.html
http://www.atmos-chem-phys-discuss.net/8/2143/2008/acpd-8-2143-2008.pdf
2143
2161
2008-02-06
A method to generate near real time UV-Index maps of Austria
B. Schallhart
barbara.schallhart@i-med.ac.at
M. Blumthaler
J. Schreder
J. Verdebout
Division of Biomedical Physics, Innsbruck Medical University, Muellerstrasse 44, 6020 Innsbruck, Austria
CMS Ing.Dr.Schreder GmbH, Eggerstrasse 8, 6322 Kirchbichl, Austria
European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Via E. Fermi 1, 21020 Ispra (VA), Italy
A method is presented that combines individual ground based ultraviolet (UV)
measurements from the Austrian UVB monitoring network and area-wide data of
the distribution of clouds derived from satellite images to generate a
UV-Index map all over the region. The Austrian UVB
Monitoring
network provides near real time ground based measurements of surface UV
irradiance from fifteen selected locations throughout and in the vicinity of
Austria.
The amount of ultraviolet radiation passing through the atmosphere as
measured by the UVB detectors is indicated in units of the UV-Index, the
internationally agreed unit for erythemally weighted solar UV irradiance.
Together with clear sky model calculations the measured UV-Index is used to
determine the cloud modification factor (CMF), a scaling factor giving the
reduction of radiation due to the presence of clouds. Moreover satellite
images from MSG (Meteosat Second Generation) with a time resolution of 15 min and a spatial resolution of 0.05° are received. From the
satellite images the CMFs for the area of Austria are obtained using an
algorithm provided by Jean Verdebout. Then both independent data sets of
cloud modification factors are checked for consistency by comparing satellite
derived and ground based values at the positions of the monitoring stations.
If necessary the satellite derived cloud modification factors are corrected
by about ±20% according to the results of the ground based
measurements. Afterwards realistic UV-Index maps of the whole area are
generated by scaling model derived UV-Indexes with the corresponding cloud
modification factors. Since all the data is available in almost real time,
the calculated UV-Index maps are available in the web at
<a href="http://www.uv-index.at/" target="_blank">http://www.uv-index.at/</a> with a time delay of about 30 min.
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