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| Titel |
Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers |
| VerfasserIn |
J. B. A. Muller, C. J. Percival, M. W. Gallagher, D. Fowler, M. Coyle, E. Nemitz |
| 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 ; 3, no. 1 ; Nr. 3, no. 1 (2010-02-08), S.163-176 |
| Datensatznummer |
250000821
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| Publikation (Nr.) |
 copernicus.org/amt-3-163-2010.pdf |
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| Zusammenfassung |
| We present a systematic intercomparison study of eddy covariance ozone flux
measurements made using two fast response dry chemiluminescence analysers.
Ozone deposition was measured over a well characterised managed grassland
near Edinburgh, Scotland, during August 2007. A data quality control
procedure specific to these analysers is introduced. Absolute ozone fluxes
were calculated based on the relative signals of the dry chemiluminescence
analysers using three different methods and the results are compared for
both analysers. It is shown that the error in the fitted analyser
calibration parameters required for the flux calculations provides a
substantial source of uncertainty in the fluxes. The choice of the
calculation method itself can also constitute an uncertainty in the flux as
the calculated fluxes by the three methods do not agree within error at all
times. This finding highlights the need for a consistent and rigorous
approach for comparable datasets, such as e.g. in flux networks. Ozone
fluxes calculated by one of the methods were then used to compare the two
analysers in more detail. This systematic analyser comparison reveals
half-hourly flux values differing by up to a factor of two at times with the
difference in mean hourly flux ranging from 0 to 23% with an error in
the mean daily flux of ± 12%. The comparison of analysers shows
that the agreement in fluxes is excellent for some days but that there is an
underlying uncertainty as a result of variable analyser performance and/or
non-linear sensitivity. |
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