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Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers

Muller, J. B. A.; Percival, C. J.; Gallagher, M. W.; Fowler, D.; Coyle, M.; Nemitz, E.. 2010 Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers. Atmospheric Measurement Techniques, 3. 163-176. 10.5194/amt-3-163-2010

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Abstract/Summary

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.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/amt-3-163-2010
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes > BGC - 1.4 - Develop innovative, effective methods for monitoring fluxes, exposure and effects
CEH Sections: Billett (to 30 Nov 2013)
ISSN: 1867-1381
Additional Information. Not used in RCUK Gateway to Research.: Atmospheric Measurement Techniques is an open Access journal - to access full text, please click on the OFFICIAL URL link
NORA Subject Terms: Atmospheric Sciences
Date made live: 24 Feb 2010 14:51
URI: http://nora.nerc.ac.uk/id/eprint/9335

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