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| Titel |
Influence of the calibration on experimental UV index at a midlatitude site, Granada (Spain) |
| VerfasserIn |
M. Antón, J. E. Gil, A. Cazorla, J. Fernández-Gálvez, J. M. Vilaplana, F. J. Olmo, L. Alados-Arboledas |
| 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 ; 4, no. 3 ; Nr. 4, no. 3 (2011-03-10), S.499-507 |
| Datensatznummer |
250001798
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| Publikation (Nr.) |
 copernicus.org/amt-4-499-2011.pdf |
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| Zusammenfassung |
The ultraviolet index (UVI) is the most commonly used variable to inform
about the level and potential harmful effect of ultraviolet (UV) radiation
reaching the Earth's surface. This variable is derived from the output
signal of UV radiometers applying conversion factors from calibration
methods. This paper focused on the influence of the use of two of these
methods (called one-step and two-steps methods) on the experimental UVI
measured by a YES UVB-1 radiometer located in a midlatitude station, Granada
(Spain) for the period 2006–2009. In addition, it also analyzes the
deviation from the UVI values obtained when the manufacturer's calibration
factors are applied. For this goal, a detailed characterization of the UVB-1
radiometer from the first Spanish calibration campaign of broadband UV
radiometers at the "El Arenosillo" INTA station in 2007 was used. In
addition, modeled UVI data derived from the LibRadtran/UVSPEC radiative
transfer code are compared with the experimental values recorded at Granada
for cloud-free conditions.
Absolute mean differences between measured and modeled UVI data at Granada
were around 5% using the one-step and two-steps calibration methods,
indicating an excellent performance of these two techniques for obtaining
UVI data from the UVB-1 radiometer. Conversely, the application of the
manufacture's calibration factor produced a large overestimation (~14%)
of the UVI values, generating unreliable alarming high UVI data in
summer. Thus, the number of days with an extreme erythemal risk (UVI higher
than 10) increased up to 46% between May and September at Granada. This
percentage reduced to a more reliable value of 3% when the conversion
factors obtained with the two-steps calibration method are used. These
results evidence the need for a sound calibration of the broadband UV
instruments in order to obtain reliable measurements. |
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