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https://doi.org/10.5194/bg-2018-458
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-458
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 05 Nov 2018

Research article | 05 Nov 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Source Partitioning of H2O and CO2 Fluxes Based on High Frequency Eddy Covariance Data: a Comparison between Study Sites

Anne Klosterhalfen1, Alexander Graf1, Nicolas Brüggemann1, Clemens Drüe2, Odilia Esser1, María Pat González Dugo3, Günther Heinemann2, Cor M. J. Jacobs4, Matthias Mauder5, Arnold F. Moene6, Patrizia Ney1, Thomas Pütz1, Corinna Rebmann7, Mario Ramos Rodríguez3, Todd M. Scanlon8, Marius Schmidt1, Rainer Steinbrecher5, Christoph K. Thomas9, Veronika Valler1, Matthias J. Zeeman5, and Harry Vereecken1 Anne Klosterhalfen et al.
  • 1Agrosphere Institute, IBG-3, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
  • 2Department of Environmental Meteorology, University of Trier, 54296 Trier, Germany
  • 3IFAPA – Consejería de Agricultura, Pesca y Desarrollo Rural, Centro Alameda del Obispo, 14080 Córdoba, Spain
  • 4Wageningen Environmental Research, Wageningen University and Research, 6708 PB Wageningen, the Netherlands
  • 5Institute of Meteorology and Climate Research, IMK-IFU, Karlsruhe Institute of Technology (KIT), 82467 Garmisch-Partenkirchen, Germany
  • 6Meteorology and Air Quality Group, Wageningen University and Research, 6708 PB Wageningen, the Netherlands
  • 7Department Computational Hydrosystems, Helmholtz Centre for Environmental Research (UFZ), 04318 Leipzig, Germany
  • 8Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, United States
  • 9Micrometeorology Group, University of Bayreuth, 95447 Bayreuth, Germany

Abstract. For an assessment of the role of soil and vegetation in the climate system, a further understanding of the flux components of H2O and CO2 (e.g., transpiration, soil respiration) and their interaction with physical conditions and physiological functioning of plants and ecosystems is necessary. To obtain magnitudes of these flux components, we applied the source partitioning approaches after Scanlon and Kustas (2010; SK10) and after Thomas et al. (2008; TH08) to high frequency eddy covariance measurements of twelve study sites including various ecosystems (croplands, grasslands, and forests) in a number of countries. Both partitioning methods are based on higher-order statistics of the H2O and CO2 fluctuations, but proceed differently to estimate transpiration, evaporation, net primary production, and soil respiration. We compared and evaluated the partitioning results obtained with SK10 and TH08 including slight modifications of both approaches. Further, we analyzed the interrelations between turbulence characteristics, site characteristics (such as plant cover type, canopy height, canopy density and measurement height), and performance of the partitioning methods. We could identify characteristics of a data set as prerequisite for a sufficient performance of the partitioning methods.

SK10 had the tendency to overestimate and TH08 to underestimate soil flux components. For both methods, the partitioning of CO2 fluxes was more irregular than of H2O fluxes. Results derived with SK10 showed relatively large dependencies on estimated water use efficiency (WUE) at leaf-level, which is needed as an input. Measurements of outgoing longwave radiation used for the estimation of foliage temperature and WUE could slightly increase the quality of the partitioning results. A modification of the TH08 approach, by applying a cluster analysis for the conditional sampling of respiration/evaporation events, performed satisfactorily, but did not result in significant advantages compared to the other method versions (developed by Thomas et al., 2008). The performance of each partitioning approach was dependent on meteorological conditions, plant development, canopy height, canopy density, and measurement height. Foremost, the performance of SK10 correlated negatively with the ratio between measurement and canopy height. The performance of TH08 was more dependent on canopy height and leaf area index. It was found, that all site characteristics which increase dissimilarities between scalars enhance partitioning performance for SK10 and TH08.

Anne Klosterhalfen et al.
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Status: final response (author comments only)
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Anne Klosterhalfen et al.
Anne Klosterhalfen et al.
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To obtain magnitudes of flux components of H2O and CO2 (e.g., transpiration, soil respiration), we applied the source partitioning approaches after Scanlon and Kustas (2010) and after Thomas et al. (2008) to high frequency eddy covariance measurements of twelve study sites including various ecosystems (croplands, grasslands, and forests) in a number of countries. We analyzed the interrelations between turbulence characteristics, site characteristics, and performance of both partitioning methods.
To obtain magnitudes of flux components of H2O and CO2 (e.g., transpiration, soil respiration),...
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