Journal Article

PreJuSER-1445

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Photolysis frequency measurement techniques: results of a comparison within the ACCENT project

Bohn, B.FZJ* ; Corlett, G. K. ; Gillmann, M. ; Sanghavi, S. ; Stange, G. ; Tensing, E. ; Vrekoussis, M. ; Bloss, W. J. ; Clapp, L. J. ; Kortner, M. ; Dorn, H.-P.FZJ* ; Monks, P. S. ; Platt, U. ; Plass-Dülmer, C. ; Mihalopoulos, N. ; Heard, D. E. ; Clemitshaw, K. C. ; Meixner, F. X. ; Prevot, A. S. H. ; Schmitt, R.

2008
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/8601  doi:10.5194/acp-8-5373-2008

Abstract: An intercomparison of different radiometric techniques measuring atmospheric photolysis frequencies j(NO2), j(HCHO) and j((OD)-D-1) was carried out in a two-week field campaign in June 2005 at Julich. 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((OD)-D-1)-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 wave-length range below 350 nm. For j((OD)-D-1), 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 sing-le 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((OD)-D-1)-FR, conversion from output voltages to j((OD)-D-1) 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 sonic J((OD)-D-1)-FR indicated drifts of calibration factors.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

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Research Program(s):

1. Atmosphäre und Klima (P22)

Appears in the scientific report 2008

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Database coverage:
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