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| Titel |
Photolysis frequency measurement techniques: results of a comparison within the ACCENT project |
| VerfasserIn |
B. Bohn, G. K. Corlett, M. Gillmann, S. Sanghavi, G. Stange, E. Tensing, M. Vrekoussis, W. J. Bloss, L. J. Clapp, M. Kortner, H.-P. Dorn, P. S. Monks, U. Platt, C. Plass-Dülmer, N. Mihalopoulos, D. E. Heard, K. C. Clemitshaw, F. X. Meixner, A. S. H. Prévôt, R. Schmitt |
| 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. 17 ; Nr. 8, no. 17 (2008-09-10), S.5373-5391 |
| Datensatznummer |
250006370
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| Publikation (Nr.) |
 copernicus.org/acp-8-5373-2008.pdf |
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| Zusammenfassung |
| An intercomparison of different radiometric techniques measuring atmospheric photolysis
frequencies j(NO2), j(HCHO) and j(O1D) was carried out
in a two-week field campaign in June 2005 at Jülich, Germany.
Three double-monochromator based spectroradiometers (DM-SR), three
single-monochromator based spectroradiometers with diode-array
detectors (SM-SR) and seventeen filter radiometers (FR) (ten
j(NO2)-FR, seven j(O1D)-FR) took part in this
comparison. For j(NO2), all spectroradiometer results agreed
within ±3%. For j(HCHO), agreement was slightly poorer
between −8% and +4% of the DM-SR reference result. For the
SM-SR deviations were explained by poorer spectral resolutions and
lower accuracies caused by decreased sensitivities of the
photodiode arrays in a wavelength range below 350 nm. For
j(O1D), the results were more complex within +8% and
−4% with increasing deviations towards larger solar zenith
angles for the SM-SR. The direction and the magnitude of the
deviations were dependent on the technique of background
determination. All j(NO2)-FR showed good linearity with
single calibration factors being sufficient to convert from output
voltages to j(NO2). Measurements were feasible until sunset
and comparison with previous calibrations showed good long-term
stability. For the j(O1D)-FR, conversion from output voltages
to j(O1D) needed calibration factors and correction functions
considering the influences of total ozone column and elevation of
the sun. All instruments showed good linearity at photolysis
frequencies exceeding about 10% of maximum values. At larger
solar zenith angles, the agreement was non-uniform with deviations
explainable by insufficient correction functions. Comparison with
previous calibrations for some j(O1D)-FR indicated drifts of
calibration factors. |
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