HR: 1340h
AN: B33E-1664    [Abstracts]
TI: Quality control and improvement of eddy flux data for the CarboEurope-IP network
AU: Mauder, M
EM: mauderm@agr.gc.ca
AF: Agriculture and Agri-Food Canada Research Branch, 960 Carling Ave, Ottawa, ON K1A0C6, Canada
AU: * Goeckede, M
EM: Mathias.Goeckede@oregonstate.edu
AF: Department of Forest Science, Oregon State University, Richardson Hall, Corvallis, OR 97331, United States
AU: Foken, T
EM: thomas.foken@uni-bayreuth.de
AF: Department of Micrometeorology, University of Bayreuth, Universitaetsstrasse 30, Bayreuth, 95441, Germany
AB: A site evaluation based on footprint modelling and a comparison of eddy-covariance software are two major components of QA/QC activities within the CarboEurope-IP network. We applied a site evaluation approach combining Lagrangian Stochastic footprint modelling with a quality assessment approach for eddy-covariance data to 25 forested sites of the CarboEurope-IP network. The analysis addresses the spatial representativeness of the flux measurements, instrumental effects on data quality, spatial patterns in the data quality, and the performance of the coordinate rotation method. Our findings demonstrate that application of a footprint filter could strengthen the CarboEurope-IP flux database, since only one third of the sites is situated in truly homogeneous terrain. Almost half of the sites experience a significant reduction in eddy-covariance data quality under certain conditions, though these effects are mostly constricted to a small portion of the dataset. Reductions in data quality of the sensible heat flux are mostly induced by characteristics of the surrounding terrain, while the latent heat flux is subject to instrumentation-related problems. The Planar-Fit coordinate rotation proved to be a reliable tool for the majority of the sites using only a single set of rotation angles. Overall, we found a high average data quality for the CarboEurope-IP network, with good representativeness of the measurement data for the specified target land cover types. Furthermore, the results from seven commonly used software packages for four five-day datasets from different sites were compared to assess the uncertainty of carbon dioxide flux estimates due to differences in post-processing. Data preparation, coordinate rotation and the implementation of the correction for high frequency spectral losses were identified as crucial processing steps leading to significant discrepancies in the carbon dioxide flux results. The overall comparison indicated a good although not yet perfect agreement among softwares within 5 to 10% difference for the 30-minute carbon dioxide flux values.
DE: 0394 Instruments and techniques
DE: 0400 BIOGEOSCIENCES
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0452 Instruments and techniques
SC: Biogeosciences [B]
MN: 2007 Fall Meeting