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| Titel |
Measurements of UV irradiance within the area of one satellite pixel |
| VerfasserIn |
P. Weihs, M. Blumthaler, H. E. Rieder, A. Kreuter, S. Simic, W. Laube, A. W. Schmalwieser, J. E. Wagner, A. Tanskanen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 18 ; Nr. 8, no. 18 (2008-09-23), S.5615-5626 |
| Datensatznummer |
250006388
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| Publikation (Nr.) |
 copernicus.org/acp-8-5615-2008.pdf |
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| Zusammenfassung |
| A measurement campaign was performed in the region of Vienna and its
surroundings from May to July 2007. Within the scope of this campaign
erythemal UV was measured at six ground stations within a radius of 30 km.
First, the homogeneity of the UV levels within the area of one satellite
pixel was studied. Second, the ground UV was compared to ground UV retrieved
by the ozone monitoring instrument (OMI) onboard the NASA EOS Aura
Spacecraft. During clear-sky conditions the mean bias between erythemal UV
measured by the different stations was within the measurement uncertainty of
±5%. Short term fluctuations of UV between the stations were below
3% within a radius of 20 km. For partly cloudy conditions and overcast
conditions the discrepancy of instantaneous values between the stations is
up to 200% or even higher. If averages of the UV index over longer time
periods are compared the difference between the stations decreases strongly.
The agreement is better than 20% within a distance of 10 km between the
stations for 3 h averages. The comparison with OMI UV showed for
clear-sky conditions higher satellite retrieved UV values by, on the
average, approximately 15%. The ratio of OMI to ground measured UV lies
between 0.9 and 1.5. and strongly depends on the aerosol optical depth. For
partly cloudy and overcast conditions the OMI derived surface UV estimates
show larger deviation from the ground-based reference data, and even bigger
systematic positive bias. Here the ratio OMI to ground data lies between 0.5
and 4.5. The average difference between OMI and ground measurements is +24
to +37% for partly cloudy conditions and more than +50% for overcast
conditions. |
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