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@INPROCEEDINGS{Klosterhalfen:862423,
      author       = {Klosterhalfen, Anne and Moene, Arnold F. and Schmidt,
                      Marius and Scanlon, Todd M. and Vereecken, Harry and Graf,
                      Alexander},
      title        = {{S}ensitivity {A}nalysis of a {S}ource {P}artitioning
                      {M}ethod for {H}$_2${O} and {CO}$_2$ {F}luxes via {L}arge
                      {E}ddy {S}imulations},
      reportid     = {FZJ-2019-02745},
      year         = {2019},
      note         = {Also supported by Netherlands Science Foundation under
                      contract NWO 15774},
      abstract     = {For an assessment of the role of soil and vegetation in the
                      climate system, a further understanding of the
                      fluxcomponents of H$_2$O and CO$_2$ and their interaction
                      with physical conditions and physiological functioning
                      ofplants and ecosystems is necessary. Scanlon and Sahu
                      (2008) and Scanlon and Kustas (2010) proposed a
                      sourcepartitioning method (SK10 in the following) to
                      estimate the flux components transpiration, evaporation,
                      photosynthesis,and respiration on the ecosystem scale
                      obtained by the eddy covariance method. High frequency
                      timeseries are needed, and the source partitioning is
                      estimated based on the separate application of the
                      flux-variancesimilarity theory to the stomatal and
                      non-stomatal components of the regarded fluxes, as well as
                      on additionalassumptions on water use efficiency (WUE) on
                      the leaf scale. The estimated WUE has been found to exert a
                      stronginfluence on the performance of the partitioning
                      method.\\Evaluations of SK10 with field observations suffer
                      from the fact that the real source partitioning is
                      usuallyunknown, and that various disturbances may influence
                      the correlation between H$_2$O and CO$_2$ fluctuations at
                      studysites. Therefore, we conducted Large Eddy Simulations
                      (LES), simulating the turbulent transport of H$_2$O
                      andCO$_2$ under consideration of contrasting vertical
                      sink-source-distributions in the canopy, and of soil sources
                      withvarying magnitudes. SK10 was applied to these synthetic
                      high-frequency data and the partitioning performancecould be
                      evaluated depending on canopy type, measurement height, and
                      given sink-source-distributions. For asatisfying performance
                      of SK10, a certain degree of decorrelation of the H$_2$O and
                      CO$_2$ fluctuations was needed,which was enhanced for
                      observations within the roughness sublayer, as well as by a
                      clear separation between soiland canopy sources. The
                      expected dependence of the partitioning results to the WUE
                      input could be observed,where an incorrect estimation of WUE
                      affected the flux components of soil sources stronger than
                      components ofthe canopy sink/source. As a new finding, our
                      LES study indicated that next to a precise WUE estimation,
                      thevalidity of the key assumptions made by Scanlon and Sahu
                      (2008) in the method’s derivation is a crucial pointfor a
                      correct application of SK10. Therefore, a thorough
                      assessment of the conditions at study sites affecting
                      thevalidity of these assumptions would be
                      necessary.\\Scanlon, T.M., Sahu, P., 2008. On the
                      correlation structure of water vapor and carbon dioxide in
                      the atmosphericsurface layer: A basis for flux partitioning.
                      Water Resources Research 44 (10), W10418, 15
                      pp,https://doi.org/10.1029/2008WR006932.\\Scanlon, T.M.,
                      Kustas, W.P., 2010. Partitioning carbon dioxide and water
                      vapor fluxes using correlation analysis.Agricultural and
                      Forest Meteorology 150 (1), 89-99,
                      https://doi.org/10.1016/j.agrformet.2009.09.005.},
      month         = {Apr},
      date          = {2019-04-07},
      organization  = {EGU General Assembly 2019, Wien
                       (Austria), 7 Apr 2019 - 12 Apr 2019},
      subtyp        = {After Call},
      cin          = {IBG-3},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255) / IDAS-GHG - Instrumental and Data-driven
                      Approaches to Source-Partitioning of Greenhouse Gas Fluxes:
                      Comparison, Combination, Advancement (BMBF-01LN1313A)},
      pid          = {G:(DE-HGF)POF3-255 / G:(DE-Juel1)BMBF-01LN1313A},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/862423},
}