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N2O exchange over managed grassland: Application of a quantum cascade laser spectrometer for micrometeorological flux measurements
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 443814
Author(s) Neftel, Albrecht; Ammann, Christof; Fischer, Cornelia; Spirig, Christoph; Conen, Franz; Emmenegger, Lukas; Tuzson, Bela; Wahlen, Susanne
Author(s) at UniBasel Conen, Franz
Year 2010
Title N2O exchange over managed grassland: Application of a quantum cascade laser spectrometer for micrometeorological flux measurements
Journal Agricultural and forest meteorology
Volume 150
Number 6
Pages / Article-Number 775-785
Keywords N2O flux, Eddy covariance method, Quantum cascade laser, Field measurements
Abstract A novel quantum cascade laser absorption spectrometer (QCL-AS) was tested to monitor N2O exchange fluxes over an intensively managed grassland using the eddy covariance approach. The instrument employs a continuous wave quantum cascade laser to scan over the absorption features of N2O, CH4 and water vapor at 7.8 mu m. The precision of the N2O flux measurements was determined to be 0.2 nmol m(-2) s(-1) but the accuracy can easily be affected by water vapor interferences twice as large.These water vapor interferences are not only due to the respective gas dilution effect but also due to an additional cross-sensitivity of the N2O analyzer to water vapor (0.3 ppb N2O/% H2O). Both effects cause a negative bias of similar magnitude (0.3 nmol m(-2) s(-1) flux/mmol m(-2)s(-1) H2O flux) in the flux measurements. While the dilution (or density) correction is a well known and routinely applied procedure, the magnitude of the analyzer cross-talk may depend on the specific instrumental setup and should be empirically determined. The comparison with static chamber measurements shows the necessity of the cross-talk correction; otherwise the QCL-AS based eddy covariance system would yield unrealistically large uptake of N2O. (C) 2009 Elsevier B.V. All rights reserved.
Publisher Elsevier
ISSN/ISBN 0168-1923
edoc-URL http://edoc.unibas.ch/dok/A5841230
Full Text on edoc No
Digital Object Identifier DOI 10.1016/j.agrformet.2009.07.013
ISI-Number WOS:000280076400004
Document type (ISI) ArticleProceedings Paper
 
   

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