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| Titel |
Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level |
| VerfasserIn |
P. N. Outer, A. Dijk, H. Slaper, A. V. Lindfors, H. Backer, A. F. Bais, U. Feister, T. Koskela, W. Josefsson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 5, no. 12 ; Nr. 5, no. 12 (2012-12-10), S.3041-3054 |
| Datensatznummer |
250003210
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| Publikation (Nr.) |
 copernicus.org/amt-5-3041-2012.pdf |
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| Zusammenfassung |
Long-term analysis of cloud effects on ultraviolet (UV) radiation on the
ground using spaceborne observations requires the use of instruments that
have operated consecutively. The longest data record can be built from the
reflectivity measurements produced by the instruments Total Ozone Mapping
Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth
Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on
EOS Aura since 2004. The reflectivity data produced by TOMS on Earth Probe
is only included until 2002. A comparison is made with cloud effects
inferred from ground-based pyranometer measurements at over 83 World
Radiation Data Centre stations. Modelled UV irradiances utilizing the
standard reflectivity are compared with measurements of UV irradiances at
eight European low-elevation stations. The reflectivity data of the two TOMS
instruments shows a consistent agreement, and the required corrections are
of low percentage, i.e. 2–3%. In contrast, the reflectivity product of
OMI requires correction of 7–10%, and a solar angle dependency therein
is more pronounced. These corrections were inferred from a comparison with
pyranometer data, and tested using the UV measurements. The average
reduction of UV radiation due to clouds for all sites together indicates a
small trend: a diminishing cloudiness, in line with ground-based UV
observations. Uncorrected implementation of the reflectivity data would have
indicated the opposite.
An optimal area was established for reflectivity data for the calculation of
daily sums of UV radiation. It measures approximately 1.25° in
latitudinal direction for square-shaped areas overhead the ground-based UV
stations. Such an area can be traversed within 5 to 7 h at the average
wind speeds found for the West European continent. |
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