Uncertainties in eddy covariance flux measurements assessed from CH4 and N2O observations

Summary, in English

The uncertainty in eddy covariance (EC) flux measurements is assessed for CH4 and N2O using data measured at a dairy farm site in the Netherlands in 2006 and 2007. An overview is given of the contributing uncertainties and their magnitude. The relative and absolute uncertainty of a 30 min EC flux are estimated for CH4 and N2O using N = 2185 EC fluxes. The average absolute uncertainty and its standard deviation are 500 +/- 400 ng C m(-2) s(-1) for CH4 and 100 +/- 100 ng N m(-2) s(-1) N2O. The corresponding relative uncertainties have 95% confidence interval ranging from 20% to 300% for CH4 and from 30% to 1800% for N2O. The large relative uncertainties correspond to relatively small EC fluxes. The uncertainties are mainly caused by the uncertainty due to one-point sampling which contributes on average more than 90% to the total uncertainty. The other 10% includes the uncertainty in the correction algorithm for the systematic errors. The uncertainty in a daily and monthly averaged EC flux are estimated for several flux magnitude ranges. The daily and monthly average uncertainty are smaller than 25% and 10% for CH4 and smaller than 50% and 10% for N2O, respectively, based on fluxes larger than 100 ng C m(-2) s(-1) and 15 ng N m(-2) s(-1). (C) 2009 Elsevier B.V. All rights reserved.

• Författare: P. S. Kroon; A. Hensen; H. J. J. Jonker; H. G. Ouwersloot; Alex Vermeulen; F. C. Bosveld
• Publiceringsår: 2010
• Språk: Engelska
• Sidor: 806-816
• Publikation/Tidskrift/Serie: Agricultural and Forest Meteorology
• Volym: 150
• Issue: 6
• Länkar: http://dx.doi.org/10.1016/j.agrformet.2009.08.008
• Dokumenttyp: Artikel i tidskrift
• Förlag: Elsevier
• Ämne: Physical Geography
• Nyckelord: uncertainty; N2O fluxes; CH4 fluxes; correction
• Status: Published
• ISBN/ISSN/Övrigt: ISSN: 1873-2240