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| Titel |
Quality assurance of the Brewer spectral UV measurements in Finland |
| VerfasserIn |
K. Lakkala, A. Arola, A. Heikkilä, J. Kaurola, T. Koskela, E. Kyrö, A. Lindfors, O. Meinander, A. Tanskanen, J. Gröbner, G. Hülsen |
| 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. 13 ; Nr. 8, no. 13 (2008-06-30), S.3369-3383 |
| Datensatznummer |
250006260
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| Publikation (Nr.) |
 copernicus.org/acp-8-3369-2008.pdf |
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| Zusammenfassung |
| The quality assurance of the two Brewer spectrophotometers of the
Finnish Meteorological Institute is discussed in this paper. The
complete data processing chain from raw signal to high quality
spectra is presented. The quality assurance includes daily
maintenance, laboratory characterizations, calculation of long-term
spectral responsivity, data processing and quality assessment. The
cosine correction of the measurements is based on a new method, and
is included in the data processing software. The results showed that
the actual cosine correction factor of the two Finnish Brewers can
vary between 1.08–1.13 and 1.08–1.12, respectively, depending on the
sky radiance distribution and wavelength. The temperature
characterization showed a linear temperature dependence between the
instruments' internal temperature and the photon counts per cycle,
and a temperature correction was used for correcting the
measurements. The long-term spectral responsivity was calculated
using the time series of several lamps using two slightly different
methods. The long-term spectral responsivity was scaled to the
irradiance scale of the Helsinki University of Technology (HUT) for
the whole of the measurement time-periods 1990–2006 and 1995–2006
for Sodankylä and Jokioinen, respectively. Both Brewers have
participated in many international spectroradiometer comparisons,
and have shown good stability. The differences between the Brewers
and the portable reference spectroradiometer QASUME have been within
5% during 2002–2007. |
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